Thyroid Mass Is Again Seen Extending Inferiorly Into the Superior Mediastinum.
Insights Imaging. 2013 Feb; four(1): 29–52.
A diagnostic approach to the mediastinal masses
Sergi Juanpere
1Department of Diagnostic Radiology, Hospital Sant Pau i Santa Tecla, 14 Rambla Vella, 43003 Tarragona, Kingdom of spain
Noemí Cañete
2Department of Diagnostic Radiology, Dr. Josep Trueta Academy Hospital, Girona, Spain
Pedro Ortuño
2Section of Diagnostic Radiology, Dr. Josep Trueta Academy Hospital, Girona, Spain
Sandra Martínez
threeDepartment of Thoracic Surgery, Guy's Hospital, London, U.k.
Gloria Sanchez
iiSection of Diagnostic Radiology, Dr. Josep Trueta Academy Hospital, Girona, Espana
Lluis Bernado
4Department of Anatomical Pathology, Dr. Josep Trueta University Hospital, Girona, Spain
Received 2012 Jul 12; Revised 2012 Oct 23; Accustomed 2012 Oct 31.
Abstract
Groundwork
Multiple different types of mediastinal masses may be encountered on imaging techniques in symptomatic or asymptomatic patients. The location and composition of these lesions are disquisitional to narrowing the differential diagnosis.
Methods
Radiological compartmentalisation of the mediastinum helps in focusing the diagnosis of masses on the ground of their site. Some diseases, however, practise not occur exclusively in any specific compartment and tin can spread from one compartment to another.
Results
Tissular components of the mass, the degree of vascularisation and the relationships with mediastinal structures assessed past computed tomography (CT) or magnetic resonance imaging (MRI) are a leading edge of the radiological diagnosis. Special applications at MRI have been developed over the recent years in order to identify accurately tissular components of the mediastinal masses. The likelihood of malignancy of the mediastinal masses is influenced by the symptomatology and the age of the patient. This article reviews the most commonly encountered mediastinal masses considering clinical history and manifestations, anatomical position and certain details seen on different imaging modalities that allow correct diagnosis in many cases.
Conclusion
Familiarity with the radiological features of mediastinal masses facilitates accurate diagnosis, differentiation from other mediastinic processes and, thus, optimal patient handling.
Education Points
• CT and MRI are important for the diagnosis of mediastinal masses.
• The location and tissue characteristics on imaging studies are critical to narrow down the differential diagnosis of mediastinal masses.
• Symptomatology and patient age touch the likelihood of malignancy.
Keywords: Mediastinum, Multidetector computed tomography, Magnetic resonance imaging, Thymoma, Cysts
Introduction
Mediastinal masses span a wide histopathological and radiological spectrum. The most frequent lesions encountered in the mediastinum are thymoma, neurogenic tumours and benign cysts, altogether representing lx% of patients with mediastinal masses [i]. Neurogenic tumours, germ cell neoplasms and foregut cysts represent 80% of childhood lesions, whereas primary thymic neoplasms, thyroid masses and lymphomas are the most common in adults [ane].
The mediastinum is demarcated by the pleural cavities laterally, the thoracic inlet superiorly and the diaphragm inferiorly. It is further divided into anterior, middle and posterior compartments by many anatomists [2]. Anterior mediastinal tumours account for 50% of all mediastinal masses, including thymoma, teratoma, thyroid disease and lymphoma [3]. Masses of the center mediastinum are typically congenital cysts while those arising in the posterior mediastinum are frequently neurogenic tumours [4].
Usual symptoms at presentation are cough, breast pain, fever/chills and dyspnea. Localising symptoms are secondary to neoplasm invasion (respiratory compromise; paralysis of the limbs, diaphragm and vocal cords; Horner syndrome; superior vena cava syndrome), while systemic symptoms are typically due to the release of backlog hormones, antibodies or cytokines.
Imaging modalities
Many mediastinal reflections can be appreciated at conventional radiography (CR), and their presence or distortion is the central to the interpretation of mediastinal abnormalities [2]. However, computed tomography (CT) is the about important tool in the evaluation of a mediastinal mass [5]. Characterisation on CT is based on specific attenuation of air, fat, h2o and calcium (Fig.1). High-resolution multiplanar reformation images display the detailed anatomical relationship of the tumour with the side by side structures. An excellent soft tissue contrast also designates magnetic resonance imaging (MRI) as an platonic tool to evaluate tumours of the mediastinum [vi]. Assessment of preoperative relationships with the pericardium, centre cavities, spinal cord and vascular involvement is a common indication. Chemical-shift MRI has been shown to be useful in distinguishing normal thymus and thymic hyperplasia from thymic neoplasms and lymphoma [7]. Diffusion-weighted MRI (DWI) is another special application that unveils infinitesimal metabolic and biophysical differences between tissues. According to Gumustas et al. [8], the mean apparent diffusion coefficient for the malignant mediastinal entities could exist significantly lower than that for the benign diseases.
Conventional radiograph tin provide information pertaining to the size, anatomical location and density of a key mass. Right: Frontal chest radiograph shows a sharply divers surface area of increased opacity with a loss of the cardiac silhouette at the border of the right side of the center (*). Contrast-enhanced CT scan reveals a thin-walled water-attenuation lesion (*) in the right cardiophrenic bending (pericardial cyst). Middle: Lateral chest radiograph and contrast-enhanced CT scan evidence a unilocular, well-divers and homogeneously hypodense mass in the anterior mediastinum with peripheral calcification (open up arrows) (thymic cyst). Left: Chest radiograph shows the aortopulmonary window with an abnormal convex border (pointer). Contrast-enhanced CT scan demonstrates a multilobulated mass in the anterior mediastinum (pointer), which accounts for the distortion of the AP window (nodular sclerosis Hodgkin disease)
Mediastinal masses
Many entities that involve the mediastinum correspond to anatomical variants or masses arising from the spine or from the digestive tract, and should not exist considered true mediastinal masses (Figs.2 and iii). Lymph node enlargement represents a frequent cause of mediastinal masses [9].
a Dissimilarity-enhanced CT browse shows a right-sided aortic arch (arrow) in an asymptomatic man with an absence of the aortic knuckle on the left. b Contrast-enhanced CT scan demonstrates a soft tissue posterior mediastinal mass (*) in a 66-year-old woman with multiple myeloma diagnosis. Notation the mass effect to the descending aorta and left auricula by the mass and the bilateral pleural effusion (open arrows)
Dissimilar masses arising from the digestive tract. a Oesophageal stenosis after Nissen fundoplication (pointer). b Posterior mediastinal mass (arrow) in relation with squamous-cell carcinoma of the oesophagus. c Oesophageal diverticulum (arrow) in a patient with oesophageal achalasia. Notation the thickened oesophagus. d Hiatal hernia is a frequent incidental finding with or without air or air-fluid level (open arrow). * Pleural effusion
Fat masses
Lipomas predominantly occur in the anterior mediastinum and are reported to represent ane.6–2.3% of all primary mediastinal tumours [10]. At CT, lipomas have homogeneous fat attenuation of approximately -100 HU. Liposarcoma oftentimes occurs in the posterior mediastinum and information technology is normally symptomatic at the time of presentation, in contrast to lipoma [11]. Inhomogeneous appearance on CT or MRI differentiates liposarcoma from lipoma [12].
Thymolipoma is a rare, benign, well-encapsulated thymic tumour that accounts for nigh 2–nine% of thymic neoplasms [10, 12–14]. Tumours occur most frequently in the cardiophrenic bending of asymptomatic young adults without sexual practice predilection. The fatty content normally constitutes fifty–85% of the lesion but has been reported to account for equally much equally 95% of the tumour [10]. Associations with myasthenia gravis, Graves affliction and haematological disorders have been reported [14]. At CR, thymolipomas may mimic cardiomegaly, excessive epicardial fat, diaphragmatic peak, lobar collapse or a pericardial cyst. CT or MRI is required to establish the diagnosis by showing a well-defined encapsulated mass that has extensive fat content and contains modest amounts of solid areas and fibrous septa [12] (Fig.4).
Thymolipoma in a 47-twelvemonth-old asymptomatic homo. Axial and coronal multiplanar reconstruction of non-contrast-enhanced CT scan show a large and well-defined mass (arrows) that has all-encompassing fat content and contains small amounts of thin fibrous septa
Cystic masses
Mediastinal primary cysts stand for 15–20% of all primary mediastinal masses [1, xv]. A smooth or oval mass with a homogeneous attenuation, with no enhancement of cyst contents and no infiltration of side by side structures are the usual CT features of beneficial mediastinal cyst (Fig.5). Any cyst may accept a higher attenuation due to its calcic, proteinaceous, mucous or haemorrhagic content. Cysts typically testify high signal intensity on T2-weighted MR images. Truthful cystic lesions should be differentiated from the cystic degenerative changes observed in many solid tumours, in lymphomas before or after treatment, or in abscesses (Fig.vi).
A well-marginated mass with a homogeneous attenuation, usually in the range of h2o attenuation (0–xx HU) and without an enhancement of the wall or infiltrative appearance are the typical features of benign mediastinal cysts. Probably thymic cystic (a) and pericardial cyst (b)
Oblique-coronal multiplanar reconstruction of dissimilarity-enhanced CT scan of a 33-year-sometime adult female with a descending necrotising mediastinitis. Hypodense para-aortic areas correspond with fluid-collections (arrows) that extend to the retroperitoneum. Pleural effusion in the fissure is also be seen (open up arrow). Note the visceral infinite involvement (arrowhead)
Bronchogenic cysts effect from abnormal ventral budding or branching of the tracheobronchial tree during embryologic development [15–17]. They are lined by respiratory epithelium and their sheathing contains cartilage, smooth musculus and mucous gland tissue. They are stable in size, except when complicated by infection or haemorrhage. Approximately xl% of bronchogenic cysts are symptomatic, resulting in coughing, dyspnea or chest pain [4]. The bronchogenic cyst is commonly located in the near carina (52%) and in the paratracheal region (19%) [5]. The inductive mediastinum is a rare location of the bronchogenic cyst [17] (Fig.7). Air within the cyst is suggestive of secondary infection and communication with the tracheobronchial tree.
Bronchogenic cyst in a 37-yr-sometime human being. a Non-contrast-enhanced CT scan shows a homogeneous anterior mediastinal mass with polish contours and oval shape (arrow). The mass is isodense relative to breast wall muscle. b T2-weighted MR image shows the same mass (arrow) with markedly high signal intensity. c Although its localisation, a bronchogenic cyst was confirmed by histological exam later surgical resection
Duplication cysts are uncommon lesions lined by gastrointestinal tract mucosa and more often than not asymptomatic. However, if they contain gastric or pancreatic mucosa, there is the added risk of haemorrhage or rupture of the cyst from mucosal secretions. The bulk of them are detected adjacent to or within the oesophageal wall (Fig.eight). Duplication cysts are indistinguishable from bronchogenic cysts on CT and MRI.
Duplication cyst in a 42-year-one-time asymptomatic man. a Contrast-enhanced CT scan shows a round well marginated mass (pointer) adjacent to the oesophagus with homogeneous h2o-attenuation. b The lesion (arrow) presents a bright point intensity on T2-weighted fatty-suppressed MR paradigm
Mediastinal neuroenteric cysts are anomalous protrusions of the leptomeninges through intervertebral foramen or defects in the vertebral body. They are associated with multiple vertebral anomalies and with neurofibromatosis [15, 16].
Pericardial cyst is a benign lesion accounting for 5–10% of all mediastinal tumours [xi]. About pericardial cysts are unilocular and commonly located in the right cardiophrenic space (Fig.9). However, they may occur anywhere in relation to the pericardium.
a Lateral chest radiograph of a 58-twelvemonth-old smoker man allergic to iodine shows a well-defined mass (*) in the cardiophrenic space and a nodular lung opacity (open arrow) in the lower lung parenchyma. b, c Non-contrast-enhanced CT browse confirms the presence of a fluid-attenuation mass (*) in the right cardiophrenic angle (pericardial cyst) and demonstrates a suspicious lung opacity (open arrows) in the right lower lobe of the lung (squamous-cell carcinoma)
Thymic cyst represents ane% of all mediastinal masses [15]. Congenital cysts derive from remnants of the thymopharyngeal duct, they are typically unilocular and contain clear fluid (Fig.10). In dissimilarity, acquired thymic cysts are much more common, tend to exist multilocular (Fig.11) and may ascend in association with neoplasms such every bit thymomas, lymphomas or germ prison cell tumours. Thymic cysts may also exist seen in the anterior mediastinum later radiation therapy of Hodgkin's disease, after inflammatory processes and occasionally in patients with AIDS, particularly in children [18].
Congenital thymic cyst in a 47-year-one-time man. Contrast-enhanced CT scan demonstrates a unilocular unenhanced lesion in the anterior mediastinum which shows a homogeneous fluid-attenuation (arrow)
Acquired thymic cyst in a 43-year-old human. a Contrast-enhanced CT scan shows a well-defined h2o-attenuation multiloculated mass (*) in the anterior mediastinum. b Sagittal T2-weighted MR sequence demonstrates a multiloculated mass with typical high signal intensitiy and fine internal septa within (pointer)
Lymphangioma is a rare benign lesion of lymphatic origin that represents 0.7–4.5% of all mediastinal tumours in adult population [15]. Lymphangiomas involve the cervix or the axillary region in more than 80% of the cases and the thorax in 10% of the cases [19] (Fig.12).
A cystic lymphangioma (as well referred to every bit hygroma) in a 47-year-old woman with retroperitoneal disease. A posterior mediastinal mass with a homogeneous fluid-attenuation is identified on CT (white arrow) and on posteroanterior chest radiograph as a mass disrupting left paraspinal line inferiorly (black arrows)
Pancreatic pseudocyst can extend into the mediastinum via the oesophageal or aortic hiatus. CT shows a thin-walled, fluid-containing cyst within the posterior mediastinum which may be in continuity with the intrapancreatic or peripancreatic fluid collections (Fig.13).
Pancreatic pseudocyst in a 52-year-old human with a recurrent pancreatitis history. Axial (a, b) and oblique-sagittal multiplanar reconstruction (c) CT scan show a sparse-walled peri-oesophageal fluid-lesion (white open up arrows) that comunicates with an intrapancreatic fluid-drove (blackness open arrows) through oesophageal hiatus past a duct fistula (white arrows)
Solid masses
Mediastinal goitre by and large represents direct face-to-face growth of a goitre into the anterior or superior mediastinum. Typical features of mediastinal goitres are encapsulated and lobulated mass with inhomogeneous appearance with cystic areas, calcifications and marked dissimilarity enhancement. (Fig.fourteen). An intrathoracic thyroid mass developing from heterotopic thyroid tissue without any connection to the thyroid in the neck is extremely rare (Fig.15a). The presence of ill-divers margins, invasion of adjacent structures and nearby lymph node enlargement suggests the diagnosis of thyroid cancer [20] (Fig.15b).
Mediastinal goitres. a Coronal multiplanar reconstruction CT browse demonstrates an anterior mediastinal mass (*) arising from the thyroid more superiorly. Notation the cystic degeneration within goitre (open pointer). b Non-contrast-enhanced CT scan shows a unilateral mediastinal goitre with peripheral areas of calcification (open up pointer). c Photo of the resected surgical specimen shows a lobulated and heterogeneous advent of the mass. d Contrast-enhanced CT scan shows a well marginated posterior mediastinal goitre (*) with marked contrast enhancement
a Heterotopic mediastinal goitre. Sagittal dissimilarity-enhanced CT browse demonstrates a well-defined mass (arrow) located in the retrosternal space which shows an intense and heterogeneous contrast enhancement due to the presence of cystic areas (*). No connection to the thyroid gland from the cervix. b Anaplastic thyroid carcinoma in a 64-year-old woman with respiratory failure. Contrast-enhanced CT scan shows an anterior mediastinal soft tissue mass (*) which surrounds cracking vessels and oesophagus and compresses trachea. Annotation the extension to the suprasternal fossa (open arrow)
Thymic hyperplasia can be divided into two singled-out histological types [13, 14]. Truthful thymic hyperplasia is defined as enlargement of the thymus, which mostly retains its normal shape. This disease entity is observed when a patient is recovering from some recent stress (such as chemotherapy, corticosteroid therapy, irradiation or thermal burns). The miracle known as rebound hypeplasia is defined as a greater than l% increase in thymic book over baseline after such stress [14]. Amid patients who undergo chemotherapy, approximately 10–25% may develop rebound hyperplasia [13]. Thymic lymphoid (follicular) hyperplasia of the thymus refers to the presence of an increased number of lymphoid follicles. It is commonly associated with autoimmune diseases, being seen in up to 65% of cases with myasthenia gravis [xiv], and it has been reported to occur in the early stages of homo immunodeficiency virus infection. At CT it may appear normal (45%), enlarged (35%) (Fig.xvi) or as a focal thymic mass (20%) [13].
Thymic lymphoid hyperplasia in a 41-yr-old woman with clinical diagnosis of myasthenia gravis. Non-contrast-enhanced CT browse shows an enlarged thymic gland (arrows) without mass effect on adjacent structures
It is important for radiologists to be able to distinguish thymic hyperplasia from tumour. Lengthened symmetric enlargement of the gland, a smooth contour and normal vessels are the key morphological features of hyperplasia, whereas neoplasm tends to manifest as a focal mass with nodular contour and necrotic or calcified foci. Detecting fat in the thymus is peculiarly relevant in these situations. According to Takahashi et al. [21], chemic-shift MRI can be useful in this situation. Thymic hyperplasia reveals a relative bespeak loss on opposed-stage chemic-shift MRI that it is dissimilar from no meaning betoken change betwixt in-phase and opposed-stage chemic-shift MR images in patients with malignancy (Fig.17).
a–c Thymic hyperplasia in a 43-year-old woman (arrows). a Non-contrast-enhanced CT scan reveals a lobulated lesion with smooth margins in inductive mediastinum. b Lesion appears slightly hyperintense on in-phase slope-echo T1-weighted MR image. c Opposed-phase gradient-echo T1-weighted MR image shows decreased betoken intensity within the lesion, confirming presence of fat. d–f Phase II thymoma (WHO type B2) in a 62-year-erstwhile woman (arrows). d Non-contrast-enhanced CT scan shows an inductive mediastinal soft tissue mass. e The lesion shows an intermediate signal intensity on in-phase slope-echo T1-weighted MR image. f There is no substantial decrease in indicate intensity relative to in-phase MR prototype on opposed-phase sequence
Thymoma is the well-nigh common primary neoplasm of the anterior mediastinum but accounts for less than 1% of all adult malignancies [22, 23]. Thymomas typically occur in patients older than 40 years of age, being rare in children, and affecting men and women equally [23]. Betwixt 20% and 30% of patients with thymoma have pressure-induced symptoms [13]. Myasthenia gravis associated with thymoma occurs near frequently in women. Betwixt 30% and 50% of patients with a thymoma have myasthenia gravis, whereas 10–15% of patients with myasthenia gravis take a thymoma.
The updated histological nomenclature elaborated by WHO in 2004 classified dissimilar types of thymomas (Tablei) on the ground of the morphology of the neoplastic epithelial cells together with the lymphocyte-epithelial cell ratio [23, 24]. In dissimilarity to histological classification, the phase of thymoma has clinical implications and it is a useful tool for management decisions. The Masaoka-Koga staging arrangement is the most ordinarily used and describes thymomas in terms of the local extension of the neoplasm [fourteen, 23–26] (Tabular array2). The Masaoka staging organisation is i of the 2 factors, including abyss of surgical resection, that most strongly correlates with prognosis of thymomas [23]. The role of imaging is to initially diagnose and properly stage thymoma, with emphasis on the detection of local invasion and afar spread of illness. Between 45 and 80% of thymomas are visible by chest radiography [22]. On CT scans, thymomas normally announced as homogeneous solid masses with soft-tissue attenuation and well-demarcated borders, located anywhere from the thoracic inlet to the cardiophrenic bending. Thymomas may be oval, round or lobulated and when they are big, cystic or necrotic degeneration may exist shown (Fig.18). Calcification may be nowadays in the capsule or throughout the mass. Certain findings, such as encasement of mediastinal structures, infiltration of fat planes, irregular interface between the mass and lung parenchyma, and direct signs of vascular involvement are highly suggestive of invasion (Fig.19). Pleural broadcasting ("drop metastases") manifests as 1 or more than pleural nodules or masses, and they are near always ipsilateral to the tumour [23] (Fig.20). Thymoma rarely presents with metastatic lymphadenopathy, metastatic pulmonary nodules or pleural effusion. At MRI, thymomas commonly appear as homogeneous or heterogeneous masses with low to intermediate indicate intensity on T1-weighted images and with high signal intensity on T2-weighted images (Fig.21). MRI can prove useful in identifying the nodular wall thickening detected in cystic thymomas, absent-minded from congenital cysts [22].
Tabular array i
WHO classification for thymoma
| 2004 WHO classification | Description |
|---|---|
| A (spindle jail cell thymoma; medullary thymoma) | Banal spindle/oval epithelial tumour cells with few or no lymphocytes |
| AB (mixed thymoma) | Mixture of a lymphocyte-poor blazon A thymoma component and a more than lymphocyte-rich type B-like component (smaller and paler than those of B1 or B2 thymomas). Lymphocytes are more numerous than in the blazon A component, but may be less numerous than in B1 thymomas |
| B1 (lymphocyte-rich thymoma; lymphocytic thymoma; organoid thymoma; predominantly cortical thymoma) | Epithelial cells with a histological appearance practically indistinguishable from the normal thymus, composed predominantly of areas resembling cortex with epithelial cells scattered in a prominent population of immature lymphocytes |
| B2 (cortical thymoma) | Tumour cells closely resembling the predominant epithelial cells of the normal thymic cortex. A groundwork population of immature T cells is always present and unremarkably outnumbers the neoplastic epithelial cells |
| B3 (epithelial thymoma; squamoid thymoma) | Medium–sized round or polygonal cells with slight atypia. The epithelial cells are mixed with a small-scale component of intraepithelial lymphocytes |
From Travis et al. [24]
Table ii
Masaoka-Koga staging organization of thymoma
| Stage | Description |
|---|---|
| I | Macroscopically and microscopically encapsulated tumour |
| IIa | Microscopic invasion through the capsule |
| IIb | Macroscopic invasion into surrounding fat tissue |
| Iii | Invasion into a neighbouring organ such every bit the pericardium, great vessels or lung |
| IVa | Pleural or pericardial dissemination |
| IVb | Lymphatic-haematogenous metastases |
From references [14, 23–26]
a, b Stage Ii thymoma (WHO type B1) in a 33-yr-old woman who presented with myasthenia gravis. Frontal chest radiograph shows a hilum overlay sign (pointer) of a suggestive anterior mediastinal mass. Contrast-enhanced CT scan confirms the presence of a low-heterogeneous anterior mediastinal mass (arrow). Notation the indentation of the arterial trunk pulmonary by the mass. c, d Stage Iii thymoma (WHO type B2) in a 54-yr-old woman. Frontal chest radiograph reveals a lobulated mediastinal mass (arrow) on the right side. Contrast-enhanced CT scan demonstrates an enhanced anterior mediastinal mass (arrow) with infiltration of surrounding fat (open arrow)
CT is the imaging modality of choice for evaluating staging thymoma. Phase IVa thymoma (WHO type B3) in a 69-yr-former woman. a, b Contrast-enhanced CT browse shows a well-circumscribed, flattened soft tissue lesion in the anterior mediastinum with calcification (arrow). Note the lobulated contour of the mass and the loss of the fat airplane between the mass and the aorta. Pleural seeding is identified every bit an enhancing pleura-based nodule (open pointer). c Irregular border between the mediastinal mass and the lung parenchyma (arrowhead) is observed as a sign of locally avant-garde affliction. Annotation the cellular bronchiolitis in the left lower lobe
Stage IVa thymoma (WHO type B2) in a 46-year-onetime human. a Contrast-enhanced CT scan reveals an anterior mediastinal mass (arrows) with irregular contours, homogeneous enhancement and peripheral and central calcification also as a pleural nodule (open arrow). b On an axial FDG-positron emission tomography (PET) prototype, the pleural nodule is FDG gorging, confirming a drop metastasis. c Image during the surgical resection. d Photomicrograph (haematoxylin-eosin stain) of tissue from the lesion shows roughly equal numbers of epithelial cells (white pointer) and lymphocytes (blackness arrow) corresponding thymoma WHO type B2
Axial (a) and coronal multiplanar reconstruction (b) of a non-contrast-enhanced CT scan of a 57-year-old man allergic to iodine with a thymoma. A solid lobulated thymic mass (*) with clumps of calcifications inside (arrowhead) is identified. Note the absence of a fatty plane between the neoplasm and the aorta (open arrow). d Coronal T2-weighted MR image shows a typical signal hyperintensity of the tumour lesion (*). c Axial dissimilarity-enhanced fat-suppressed T1-weighted MR image reveals a homogeneously enhanced solid tumour (*) which arises from the thymus. Although MRI demonstrates the presence of fat cleavage plane between ascending aorta and the neoplasm, a thymoma (WHO type A) with microscopic transcapsular invasion (Masaoka stage Two) was confirmed after surgical resection
Thymic carcinoma accounts for almost 20% of thymic epithelial tumours with a mean age of fifty years [13]. Typical advent is a multilobulated and heterogeneous mass that may contain areas of calcification or haemorrhage. Distant metastasis are nowadays at the initial diagnosis in l–65% [xiii]. Sadohara et al. [27] establish that irregular contour, necrotic or cystic components, heterogeneous enhancement, lymphadenopathy and great vessel invasion strongly favoured thymic carcinoma.
Thymic carcinoids are rare, well-differentiated neuroendocrine tumours, which have a male predilection of 3:one [13, xiv]. They often present with endocrine disorder. Thymic carcinoid ordinarily manifests every bit a large inductive mediastinal mass often with metastases.
Lymphoproliferative disorders. Main mediastinal lymphoma unremarkably occurs in the anterior mediastinum. Malignant lymphoma accounts for almost xx% of all mediastinum neoplasms in adults and 50% in children [v]. Lymphomas are the about common cause of masses in the paediatric mediastinum [18]. Hodgkin lymphoma (Fig.22) represents approximately l–70% of mediastinal lymphomas, while non-Hodgkin lymphoma comprises 15–25% [four]. Pleural and pericardial effusions are oft common features in all types of lymphoma.
A 28-year-one-time human being with Hodgkin lymphoma. Frontal breast radiograph and contrast-enhanced CT scan show a homogeneous soft tissue mass at the level of the subcarina (arrows). An aortopulmonary window lymphadenopathy tin be detected on CT scan (open up arrow). The right paratracheal stripe is not seen on frontal chest radiograph, having been most probably obliterated by a correct paratracheal lymphadenopathy (arrowhead). * Carina
Hodgkin disease (HD) has a bimodal distribution of incidence peaking in young machismo and again subsequently the historic period of 50 years [4]. Near patients feel constitutional symptoms. 4 subtypes of Hard disk drive are described: nodular sclerosis (by far the almost common histological subtype) (Fig.23), lymphocyte-rich, mixed cellularity and lymphocyte depleted HD [4, 5]. CR is abnormal in up to 76% of patients with Hd, ofttimes showing enlargement of the prevascular and paratracheal nodes [4]. Characteristic features on imaging are a homogeneous soft-tissue anterior mediastinal mass with mild to moderate dissimilarity enhancement, irregular contours, surface lobulation, absence of vascular interest, and high prevalence of associated mediastinal lymphadenopathy [three]. Cystic and necrotic changes can be identified.
Nodular sclerosis Hodgkin lymphoma in a 44-yr-old woman. Frontal chest radiograph shows a large, well-defined mediastinal mass with increased density (arrow). Contrast-enhanced CT scan shows a beefy soft tissue mass (arrows) with homogeneous CT-attenuation value occupying prevascular space. Note the left internal mammarian avenue completely surrounded by the lesion. Photomicrograph reveals numerous neoplastic lacunar cells (arrows) in a groundwork of small-scale lymphocytes, histiocytes and eosinophils, which supports the diagnosis of nodular sclerosis type Hodgkin lymphoma
The two most common forms of mediastinal non-Hodgkin disease (NHD) include diffuse large B-jail cell lymphoma and T-cell lymphoblastic lymphoma. T-cell lymphoblastic lymphoma mainly occurs in children and adolescents. The most common CT advent is a big mediastinal mass representing thymic and lymph node enlargement, which compresses the airway and cardiovascular structures (Fig.24). Low attenuation areas reflecting necrosis are commonly seen. Primary mediastinal diffuse big B-cell lymphomas tend to occur in young to middle-anile adults with a mean age of xxx [5]. It accounts for vii% of all cases of NHD and about 10% of all cases of loftier-course NHD [28]. The tumours appear as a large, smooth or lobulated, inductive mediastinal mass in nigh all patients. On CT the tumours evidence low attenuation areas, representing haemorrhage, necrosis or cystic degeneration in l% of the cases and heterogeneous enhancement in near twoscore% of the cases [5] (Fig.25). Primary mediastinal B-cell lymphoma recurs in the chest. Consequently, chest CT exam lone is sufficient for routine follow-up of these patients [28].
Axial T1-weighted MR epitome of a 16-yr-old man with a solid, large mass (arrows) in the anterior and superior mediastinum. Supra-aortic trunks are almost completely surrounded past the lesion and trachea (T) is displaced to the contralateral side by the lesion. Pathological analysis demonstrated a T-prison cell lymphoblastic lymphoma
Primary mediastinal lengthened big B-cell lymphoma in a 19-year-erstwhile man. Contrast-enhanced CT scan shows a bulky soft tissue mass in the inductive mediastinum (arrowsin a), which shows heterogeneous CT-attenuation values with cystic changes within (*). Pericardial effusion is likewise observed (open arrow in b)
Germ cell tumours (GCTs) mainly arise in gonads and in the midline of the body also, the mediastinum being the almost mutual extragonadal site. GCTs business relationship for ten–fifteen% of inductive mediastinal masses in adults and 25% in children [v]. Only 3% of them arise in the posterior mediastinum [iv]. Pathological classifications include teratomas and not-teratomatous germ cell tumours.
Teratoma is the virtually mutual mediastinal GCT [4]. Mature teratomas are usually asymptomatic and represent 60–70% of all mediastinal GCTs [v]. They are composed of well-differentiated benign tissues with predominant ectodermal element. If a teratoma contains fetal tissue or neuroendocrine tissue, it is defined as immature and malignant with a poor prognosis. On CT, teratoma most unremarkably appears as a well-defined unilocular or multilocular cystic lesion containing fluid, soft tissue and fat attenuation (Fig.26). Calcifications may be focal, rim-similar or, in rare cases, representative of teeth or bone. Mutual combinations of internal components of mature teratomas include soft tissue, fluid, fat and calcification in 39%; soft tissue, fluid and fat in 24%; and soft tissue and fluid in 15%. In xv% of the cases, mature teratomas appear as non-specific cystic lesions without fatty or calcium [5]. On MRI, teratomas typically demonstrate heterogeneous signal intensity, representing various internal elements. Fatty-fluid levels inside the lesion are virtually diagnostic of teratoma. Ruptured teratomas show an next consolidation, atelectasis and pleural or pericardial effusion than do unruptured teratomas.
Breast imaging shows well the highly heterogeneous contents of mediastinal teratomas. a Mature cystic teratoma in a 40-year-quondam man. Contrast-enhanced CT scan shows a heterogeneous anterior mediastinal mass with areas of fat (open up arrow), calcification (arrow) and fluid attenuation (*). Posterior displacement of mediastinal structures is also be seen. b Photograph of the surgical specimen. c Contrast-enhanced CT browse of an asymptomatic 24-year-old woman demonstrates a well-defined uniloculated mass located in prevascular space which shows a cystic changes within (*). Non foci of calcification were identified. d The mass was surgically removed and pathological examination confirmed a benign teratoma
The non-teratomatous germ cell tumours (NTGCT) are rare and malignant tumours which ordinarily occur in immature males and nigh frequently affect the anterosuperior mediastinum [29]. These tumours grow rapidly and develop large, bulky, ill-confining masses with lobulated shape. Primary mediastinal seminomas incorporate 25–50% of malignant mediastinal GCTs [four] and occur virtually exclusively in males during the period from the 2d to fourth decades of life [5]. At imaging, the tumours typically have homogenous appearance and show minimal contrast enhancement. Areas of degeneration due to bleeding and coagulation necrosis may be present (Fig.27). Metastasis to lymph nodes and bone does occur. Non-seminomatous germ cell tumours include yolk sac tumours, endodermal sinus tumours, embryonal carcinomas, choriocarcinomas and mixed germ cell tumours, which present as big masses typically with marked heterogeneous attenuation. At diagnosis, 85% of patients are symptomatic [four]. Invasion of adjacent structures and distant metastasis may occur. Pleural and pericardial effusions are common. Measuring AFP and ß-hCG levels is important when making the diagnosis (Fig.28).
A 19-year-old homo with seminoma. Contrast-enhanced axial CT browse demonstrates a large mass in the right side of the mediastinum with an obvious mass outcome on smashing vessels and heart. The mass shows heterogeneous CT-attenuation values probably secondary to haemorrhage and coagulation necrosis. Note besides a right pleural effusion (arrowhead) and multiple lung metastasis (arrows)
Not-seminomatous malignant germ cell neoplasm of the inductive mediastinum in a 25-year-old man with chest hurting and high serum level of α-fetoprotein at admission (25.396 ng/ml). Frontal chest radiograph shows a central mass (*). The descending aorta is conspicuously seen (arrows), indicating that the mass is not inside the posterior mediastinum. Multiple nodules in bilateral pulmonary field are also observed. A dissimilarity-enhanced CT scan confirms a mass of low attenuation (*) in the inductive mediastinum that compresses the pulmonary avenue. Bilateral lung metastasis (arrowheads) and hilar and subcarinal lymphadenopathy is identified (open arrows)
Neurogenic tumours correspond approximately 20% of all adults and 35% of all paediatric mediastinal tumours and they are the most mutual cause of a posterior mediastinal mass [30]. Seventy to fourscore percent of neurogenic tumours are benign, and nearly half are asymptomatic [4]. These tumours are mostly grouped into:
Peripheral nerve tumours, which are the virtually mutual (70%) mediastinal neurogenic tumours and originate from spinal or proximal intercostal nervus; however, they rarely ascend from the vagus, recurrent laryngeal and phrenic nerve [30] (Fig.29). Schwannomas are the most common (50%) mediastinal neurogenic tumours and often affect patients from 20 to 30 years old [30]. They are normally alone and encapsulated masses, but multiple schwannomas may exist associated with neurofibromatosis type two. The neoplasm may grow through the next intervertebral foramen and spinal culvert to produce a "dumbbell" or "hourglass" configuration. Cystic changes and haemorrhage are more than common in schwannomas than in neurofibromas. Neurofibromas are not-encapsulated soft tissue tumours and account for approximately 20% of mediastinal neurogenic tumours [30]. A sudden increment in the size of a previously stable neurofibroma and the presence of neurological symptoms suggests malignant transformation to cancerous peripheral nerve sheath tumour. These tumours are closely associated with neurofibromatosis and show more than heterogeneous signal intensity and contrast enhancement on MRI.
Peripheral nerve tumours usually prove a markedly convex mass arising from the mediastinum. a Coronal multiplanar reconstruction of contrast-enhanced CT scan of an asymptomatic 59-year-quondam human being with a mass in right superior mediastinum (pointer). Histological examination confirmed a schwannoma arising from the phrenic nervus. b Schwannoma in a 77-twelvemonth-old woman. Non-contrast-enhanced CT scan shows a well-defined and homogeneous paravertebral mass (*)
Sympathetic ganglion tumours, which comprise 25% of mediastinal neurogenic tumours and arise from neuronal cells rather than from the nerve sheath [30]. Ganglioneuromas are the almost benign and differentiated of the autonomic ganglionic tumours. Radiographically, the tumours are well-marginated, occurring along the anterolateral attribute of the spine and spanning three to five vertebrae. The "whorled appearance" is due to curvilinear bands of low signal intensity that reflects collagenous fibrous tissue in the mass on T2-weighted images. Most ganglioneuromas bear witness gradual and heterogeneous contrast enhancement. Ganglioneuroblastomas are the least common type of neurogenic neoplasm and show intermediate features in cellular maturity betwixt neuroblastoma and ganglioneuroma. Neuroblastomas are highly ambitious and readily metastasising tumours of neuroectodermal origin with a median age at diagnosis of 22 months [30]. They are heterogeneous and non-encapsulated lesions, often exhibiting haemorrhage, necrosis, calcification or cystic degeneration (Fig.30).
Neuroblastoma in a 20-year-old human being. Centric (a) and coronal (b) T2-weighted MR images, and sagittal (c) contrast-enhanced T1-weighted MR image demonstrate an expansive and heterogeneous mass in the left paravertebral space which shows cystic degeneration within (*) as well as an intensive enhancement (in c). Note the spinal involvement (arrowhead in b)
Mediastinal paraganglia. Paraganglioma is a rare neuroendocrine neoplasm of chromaffin prison cell origin. I to two percent of actress-adrenal paragangliomas occur in the thorax [30]. Aortopulmonary paragangliomas are usually asymptomatic, while aortosympathetic paragangliomas (along the sympathetic chain in the posterior mediastinum) occur in symptomatic patients related to the functional action of the tumour. These masses commonly raise brightly at enhanced CT (Fig.31). A characteristic MRI finding of paragangliomas is the presence of multiple curvilinear and punctate signal voids, which reflect high velocity flow in the intratumoral vessels, described as "salt-and-pepper" appearance.
Aortopulmonary paraganglioma in a 52-year-old woman. a Enhanced-CT scan shows a markedly enhancing lesion (pointer) located adjacent of the arch of aorta. b Prototype during the surgical remove of the lesion. Paraganglioma (white arrow); descending aorta (black pointer); vagus nervus (open pointer). c Photomicrograph demonstrated a trabecular pattern of growth and scattered ganglion-like cells surrounded by fibrovascular septa (arrows)
Clinical and radiological features of the most common mediastinal masses are detailed in Table3.
Table 3
Clinical and radiological features of the most common mediastinal masses
| Anatomical location | Imaging features (CT) | Imaging features (MRI) | Manifestations | |
|---|---|---|---|---|
| Lipoma | anterior mediastinum | encapsulated homogeneous fatty attenuation (-40 to -120 HU) | homogeneous hyperintensity on T1-WI | asymptomatic (occasionally local pinch of surrounding structures) |
| Liposarcoma | posterior mediastinum | - inhomogeneous fat attenuation | inhomogeneous appearance | symptomatic at presentation |
| - irregular areas of soft-tissue appearance | ||||
| - locally aggressive tumours | ||||
| Thymolipoma | cardiophrenic angle | - fatty-containing lesions (up to 90% fat content) | - homogeneous hyperintensity on T1-WI | - asymptomatic (occasionally local pinch of surrounding structures) |
| - variable component of soft-tissue elements | - small-scale amounts of solid areas and fibrous septa | - a/w myasthenia gravis, Graves disease and haematological disorders | ||
| Bronchogenic cyst | eye/posterior mediastinum | - well-defined homogeneous fluid attenuation (0–20 HU) | - homogeneous hyperintensity on T2-WI | 40% symptomatic at presentation |
| Duplication cyst | - variable composition of fluid if complication or presence of protein or mucoid material | - variable patterns of signal intensity on T1-WI because of variable cyst contents | asymptomatic | |
| Pericardial cyst | cardiophrenic angle | asymptomatic | ||
| Neuroenteric cyst | posterior mediastinum | - well-defined homogeneous low-attenuation paravertebral mass | homogeneous hyperintensity on T2-WI | a/w neurofibromatosis, vertebral and rib anomalies or scoliosis |
| - enlargement of intervertebral foramina | ||||
| Thymic cyst | anterior mediastinum | CONGENITAL THYMIC CYST: unilocular well-defined fluid attenuation mass | homogeneous hyperintensity on T2-WI | asymptomatic |
| Acquired THYMIC CYST: multilocular well-defined fluid attenuation mass with a clearly seen wall | homogeneous hyperintensity on T2-WI with gristly septa | a/w thymic tumours, after thoracotomy or radiation therapy for HD or as sequelae of inflamatory processes | ||
| Mediastinal goitre | anterior mediastinum | - spontaneous hyperattenuation | - heterogeneous appearance on T2-WI | asymptomatic or airway/oesophageal pinch |
| - inhomogeneous density with cystic areas and calcifications | - relatively hypointensity on T1-WI as compared with normal gland tissue, except foci of haemorrhage and cysts | |||
| - markedly contrast-enhancement | ||||
| Thymic hyperplasia | anterior mediastinum | TRUE THYMIC HYPERPLASIA: enlargement of the thymus which remains normally organised | - like MR signals to those of normal thymus | later on chemotherapy, corticosteroid therapy, irradiation or thermal burns |
| LYMPHOID HYPERPLASIA: normal, enlarged or as a focal thymic mass | - credible decrease in the point intensity of the thymus at opposed-phase images in dissimilarity to in-phase images | a/w myasthenia gravis, rheumatoid arthritis, scleroderma, Graves illness | ||
| Thymoma | inductive mediastinum | - soft-tissue attenuation | - low bespeak intensity on T1-WI | - patients older than 40 years-old |
| - mild to moderate contrast enhancement | - relatively high signal intensity on T2-WI | - asymptomatic vs pressure-induced symptoms | ||
| - occasionally, focal bleeding, necrosis, cyst formation and linear or band-similar calcifications | - complete obliteration of the adjacent fat planes highly suggests mediastinal invasion | - a/w myasthenia gravis (30-fifty%), hypogammaglobulinaemia (10%) and pure carmine cells apasia (5%) | ||
| - pleural nodules | ||||
| Thymic carcinoma | anterior mediastinum | - sick-defined soft-tissue mass | - like features on CT | - mean age of fifty years |
| - necrotic or cystic component | - absence of tumour capsule | - symptomatic at presentation | ||
| - heterogeneous contrast enhancement | ||||
| - lymphadenopathy and dandy vessel invasion | ||||
| - 50–65% distant metastases at presentation | ||||
| Lymphoma | anterior mediastinum | - homogeneous soft-tissue mass | various bespeak patterns on T1- and T2-WI | - the virtually common cause of masses in the paediatric mediastinum |
| - mild to moderate contrast enhancement | - HD: bimodal distribution of incidence. Constitutional symptoms | |||
| - cystic and necrotic changes | - TCLL: children and adolescents. Pressure-induced symptoms | |||
| - absenteeism of vascular involvement | - DLBCL: mean age of xxx years | |||
| - mediastinal lymphadenopathy | ||||
| - pleural and pericardial effusions | ||||
| Teratoma | anterior mediastinum | - well-defined unilocular or multilocular cystic lesion containing fluid, soft tissue, and fat attenuation. Calcifications may be present | - heterogeneous signal intensity | usually asymptomatic |
| - 15% as nonspecific cystic lesion | - fat-fluid levels within the lesion are virtually diagnostic of teratoma | |||
| NTGCT | inductive mediastinum | - heterogeneous ill-circumscribed big mass | heterogeneous signal intensity | - symptomatic immature males |
| - pericardial and pleural effusion | - tumour markers ß–hCG and AFP | |||
| - involvement of great vessels | ||||
| - distant metastases | ||||
| Schwannoma | posterior mediastinum | - markedly convex mass | homogeneous or heterogeneous high signal intensity on T2-WI | - patients from 20 to 30 years erstwhile |
| - "dumbbell" or "hourglass" configuration | - a/w neurofibromatosis type two when multiple | |||
| - cystic, bleeding and calcification elements are mutual | ||||
| SGT | posterior mediastinum | - well-divers or ill-defined mass oriented along the anterolateral surface of several vertebrae | heterogeneous high signal intensity on T2-WI | children and young adults |
| - "whorled appearance" | ||||
| Paraganglioma | APP: forth nifty vessels | hypervascular tumours | "table salt and pepper" appearance | APP: asymptomatic patients older than forty years |
| ASP: posterior mediastinum | ASP: younger adults. One-half of them present symptoms |
NTGCT non-teratomatous germ jail cell tumours, SGT sympathetic ganglion tumours, AFP alpha-fetoprotein, ß–hCG beta man chorionic gonadotropin, HD Hodgkin disease, TCLL T-cell lymphoblastic lymphoma, DLBCL lengthened big B-prison cell lymphoma, APP aortopulmonary paraganglioma, ASP aortosympathetic paraganglioma, a/w association with, WI weighted imaging
Uncommon mediastinal masses
Parathyroid adenomas may be seen in ectopic locations, the mediastinum being the most commonly site. High-resolution ultrasonography (US) is recognised as a tool for detecting cervical parathyroid lesions. As information technology enlarges, an abnormal gland appears equally a hypoechoic, and frequently anechoic, lesion, often posterior in location to the thyroid. As the gland enlarges, it tin develop lobularity and foci of echogenicity. Colour Doppler assessment of parathyroid lesions is a useful integration of grey-scale Usa and may be helpful in featuring parathyroid lesions. The color Doppler patterns termed "parenchymal" (design Four, internal flow) and "vascular pole" (blueprint 2, focal peripheral flow) are typical of parathyroid lesions [31]. The different colour Doppler U.s.a. patterns seem to be influenced by many factors equally the location of the gland and the caste of vascularity. These tumours tend to exist pocket-sized and may contain calcifications at CT. Technetium-99 Sestamibi SPECT scans are more effective for their diagnosis (Fig.32). Fibrosing mediastinitis is a dense fibrosis which progressively encases and somewhen obliterates the lumen of the mediastinal vessels and airways (Fig.33). Haematoma. High attenuation of haematomas can be observed on unenhanced CT scans during the first 72 h (Fig.34). When the hematoma ages its attenuation decreases at CT in a centripetal fashion. Haemangiomas in the mediastinum are rare and the may be associated with Rendu-Osler syndrome. Sarcomas other than vascular or neural origin, including fibrosarcomas, osteosarcomas and chondrosarcomas, are also very uncommon. Extramedullary haematopoiesis in posterior mediastinum is some other entity to take into business relationship.
Parathyroid adenoma in a 66-yr-onetime man with hypercalcaemia, hypophosphataemia and elevated PTH values. Tc-99m MIBI scan shows a focus of hyperactivity (black arrow) adjacent to the lower pole of left thryoid lobule. Enhanced-CT scan shows a superior mediastinal enhanced mass (white arrow)
Idiopathic fibrosing mediastinitis in a 64-year-old man. a Coronal multiplanar reconstruction and axial b constrast-enhanced CT scan prove an infiltrating soft tissue mass (white arrows) in mediastinum encasing major vessels. Punctate calcifications are observed (blackness arrows) as well every bit an pinnacle of the correct hemidiaphragm (open arrow) secondary to the phrenic nerve involvement
a Contrast-enhanced CT browse of a man who had suffered a traffic accident. An infiltrative mediastinal haematoma is identified with subtle areas of loftier CT-attenuation values (arrow). Bilateral pleural effusion (*) and a sternum fracture (open pointer) are also observed. b Iatrogenic mediastinal haematoma (arrow) in a 64-year-old human secondary to bronchoscopy with transtracheal biopsy. Notation the high attenuation value of the lesion compared with muscular tissue
Follow-up
In assessment of mediastinal disease, cross-sectional imaging techniques allow excellent visualisation of the mediastinum. CT is mostly the first-choice modality of diagnostic imaging. MRI plays an increasing role in this disease due to the existence of new available MR techniques on mediastinum imaging.
On each of CT and MR scanning, the size of tumour, profile, perimeter of capsule, septum, haemorrhage, necrotic or cystic component, homogeneity within tumour, presence of mediastinal lymphadenopathy, pleural effusion and great vessel invasion are assessed. In add-on, presence of calcification are assessed on CT and signal intensities of the tumour are assessed on MRI.
Imaging plays an essential role in the diagnosis, staging and follow-upward of mediastinal disease. Consummate resection is the mainstay of treatment in many mediastinal tumours and the ability to attain a consummate resection appears to exist the most of import prognostic cistron. Currently, CT is the modality nearly unremarkably used for follow-upward afterwards treatment. The goal of follow-up is to find recurrence as early as possible. CT findings may serve as predictors of tumour invasiveness and of postoperative recurrence or metastases.
In Tablefour nosotros summarise some pedagogy points and imaging pitfalls for the diagnostic approach to mediastinal masses before and afterwards treatment.
Table 4
Teaching points and imaging pitfalls for the diagnostic approach to mediastinal masses before and afterwards handling
| • CT is accurate in distinguishing mediastinal masses which usually differ in their appearance and the blueprint of metastatic spread, both of which are readily detected by chest CT |
| • Pericardial fat pads and lipomatosis are correctly interpreted equally normal findings rather than possible pathological lesions |
| • When lipoma and liposarcoma are situated in the cardiophrenic space, the imaging findings are very similar to those of Morgagni hernia |
| • MRI more than accurately distinguishes between cystic and solid lesions than CT |
| • Soft-tissue components associated with cystic lesions can exist related to a malignant procedure (e.grand. soft-tissue nodules in a cystic inductive mediastinal lesion propose that the lesion is a cystic thymoma rather than a built cyst) |
| • Not-neoplastic thymic enlargement must not exist confused with thymoma. The normal thymus in young children and the hyperplastic thymus may mimic a mass |
| • When differentiation between not-neoplastic thymic enlargement and thymoma cannot be achieved at CT or conventional MRI, chemic-shift MRI with in-stage and out-of-phase gradient-echo sequences can exist helpful |
| • Thymoma rarely manifests with lymphadenopathy, pleural effusions, or extrathoracic metastases |
| • The part of imaging is to initially diagnose and properly stage thymoma, with accent on the detection of local invasion and distant spread of disease, to place candidates for preoperative neoadjuvant therapy |
| • Tardily recurrence in thymoma is non uncommon. Imaging of treated patients is directed at identifying resectable recurrent affliction, since patients with completely resected recurrent disease have similar outcomes as those without recurrence [23] |
| • Findings associated with significantly more frequent recurrence and metastases of thymic tumours include lobulated or irregular contour, oval shape, mediastinal fat invasion or swell vessel invasion and pleural seeding |
| • Mediastinal lymphadenopathy, pleural effusions, and pulmonary metastases are characteristic of thymic carcinoma or non-teratomatous germ cell tumour |
| • Lymphoproliferative disorders typically present pleural effusions, pericardial fluid, and mediastinal lymphadenopathy in many cases |
| • Heterogeneous appearance (due to necrosis, cystic change, or bleeding) is typical of thymic carcinoma, lymphoma, sympathetic ganglion tumour, peripheral nervus tumour and non-teratomatous germ jail cell tumour. It can exist seen in about one-tertiary of thymomas |
| • A cystic inductive mediastinal mass with intrinsic fatty attenuation typically represents a mature teratoma |
Conclusion
Tumours of the mediastinum stand for a broad diversity of disease state. The location and composition of a mass is disquisitional to narrowing the differential diagnosis. The clinical spectrum of mediastinal masses tin range from beingness asymptomatic to producing compressive symptoms. Although many of these masses have like imaging appearances, clinical history, anatomical position and certain details seen at CT and MRI imaging allow correct diagnosis in many cases.
Acknowledgments
The authors gratefully acknowledge the contribution of technicians, surgeons and pathologists of the hospitals listed above, without whose efforts this work would not take been possible. The authors thank Isabel Coll for the English correction and assistance.
Open Admission
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