Thymic carcinoma
Summary
High-grade malignant thymic epithelial tumour. Compared with thymoma, it more often shows infiltrative invasion, nodal metastases, and distant spread, so prognosis is generally worse.
Clinical
- Usually adults; very rare in children
- Paraneoplastic syndromes (e.g. Myasthenia gravis) are uncommon compared with thymoma
- Often presents at locally advanced stage
Imaging features
CT (workhorse)
- Large anterior mediastinal mass
- Irregular / infiltrative margins
- Heterogeneous enhancement with necrosis or haemorrhage common
- Local invasion: pericardium, great vessels (encasement), lung, chest wall
- Calcification may be present (not specific)
- Lymphadenopathy (mediastinal ± supraclavicular) is more suggestive than in thymoma
- Look for spread: pleural nodules/effusion, pulmonary metastases, distant metastases
MRI
- Helps assess pericardial and vascular invasion when CT equivocal
FDG PET/CT
- Often FDG-avid; useful for staging (nodes + distant disease) and response assessment
Warning
Imaging can strongly suggest thymic carcinoma, but histology is required for definitive diagnosis. Report as “aggressive thymic epithelial tumour suspicious for thymic carcinoma” when appropriate.
Features favouring thymic carcinoma over thymoma
- Infiltrative invasion (vascular encasement, pericardial/chest wall invasion)
- Mediastinal/supraclavicular lymphadenopathy
- Pleural/pericardial disease (nodules, effusion)
- Distant metastases
- More heterogeneous, necrotic mass with irregular margins
