Primary intrathoracic malignant mesenchymal tumours: computed tomography features of a rare group of chest neoplasms

OBJECTIVES: To describe the computed tomography (CT) features in a case series of primary intrathoracic extracardiac malignant mesenchymal tumours (sarcomas). METHODS: A 5-year retrospective research was conducted, and 18 patients were selected. CT exams were reviewed by two chest radiologists, blinded to tumour pathological type, origin and grade. Lesions were described in relation to location, size, shape, margins, enhancement, presence of cavitation, calcifications, ground glass component, intratumoural enhanced vessels, pleural effusion, pleural tags, lymphangitis, chest wall/rib involvement and pathological lymph nodes. RESULTS: The readers described five pulmonary, six mediastinal and seven pleural/wall based lesions. Mean largest diameter was 103 mm. The most frequent shape was irregular (n = 12), most predominant margin was smooth (n = 12) and enhancement was mostly heterogeneous (n = 8). Intratumoural vessels and pleural effusion were seen in 11 patients. Pathological lymph nodes were present in four cases and calcifications in two cases. CONCLUSIONS: Some frequent radiological features were described independently of tumour location and subtype. A sarcoma should be included as a major differential diagnosis when the radiologist faces an intrathoracic mass of large size (>70 mm) but with well defined smooth or lobulated margins, especially if presenting intratumoural vessels, associated pleural effusion but no significant lymphadenopathy. MAIN MESSAGES: • Malignant mesenchymal tumours (sarcomas) are rare and can arise from any structure in the chest. • Intrathoracic sarcomas show some frequent radiological features, independent of location and type. • Some CT features may help the radiologist suspect for a sarcoma instead of other more common tumours.