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 fat attenuation (-40 to -120 HU) | homogeneous hyperintensity on T1-WI | asymptomatic (occasionally local compression 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 | - fat-containing lesions (up to 90% fat content) | - homogeneous hyperintensity on T1-WI | - asymptomatic (occasionally local compression of surrounding structures) |
- variable component of soft-tissue elements | - small amounts of solid areas and fibrous septa | - a/w myasthenia gravis, Graves disease and haematological disorders | ||
Bronchogenic cyst | middle/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 fibrous 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 compression |
- 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 | - similar MR signals to those of normal thymus | after chemotherapy, corticosteroid therapy, irradiation or thermal burns |
LYMPHOID HYPERPLASIA: normal, enlarged or as a focal thymic mass | - apparent decrease in the signal intensity of the thymus at opposed-phase images in contrast to in-phase images | a/w myasthenia gravis, rheumatoid arthritis, scleroderma, Graves disease | ||
Thymoma | anterior mediastinum | - soft-tissue attenuation | - low signal 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 haemorrhage, necrosis, cyst formation and linear or ring-like calcifications | - complete obliteration of the adjacent fat planes highly suggests mediastinal invasion | - a/w myasthenia gravis (30-50%), hypogammaglobulinaemia (10%) and pure red cells apasia (5%) | ||
- pleural nodules | ||||
Thymic carcinoma | anterior mediastinum | - ill-defined soft-tissue mass | - similar features on CT | - mean age of 50 years |
- necrotic or cystic component | - absence of tumour capsule | - symptomatic at presentation | ||
- heterogeneous contrast enhancement | ||||
- lymphadenopathy and great vessel invasion | ||||
- 50–65% distant metastases at presentation | ||||
Lymphoma | anterior mediastinum | - homogeneous soft-tissue mass | various signal patterns on T1- and T2-WI | - the most 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 | |||
- absence of vascular involvement | - DLBCL: mean age of 30 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 | anterior mediastinum | - heterogeneous ill-circumscribed large mass | heterogeneous signal intensity | - symptomatic young 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 old |
- “dumbbell” or “hourglass” configuration | - a/w neurofibromatosis type 2 when multiple | |||
- cystic, haemorrhage and calcification elements are common | ||||
SGT | posterior mediastinum | - well-defined 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: along great vessels | hypervascular tumours | “salt and pepper” appearance | APP: asymptomatic patients older than 40 years |
ASP: posterior mediastinum | ASP: younger adults. Half of them present symptoms |