Non-seminomatous germ-cell tumours include embryonal carcinoma, choriocarcinoma, endodermal sinus tumour and tumours with mixtures of these cell types. Malignant non-seminomatous germ-cell tumours are usually seen in young adults and are much more common in men (>90%) than in women. They are commonly more symptomatic than teratomas, from mass effect or invasion of adjacent structures. 

The plain radiographic findings are similar, except that the malignant tumours are more often lobular in outline. Fat density and visible calcifications are rare. Because these are malignant tumours, they grow rapidly and metastasise readily to the lungs, bones or, less often, pleura (Fig. 1). CT often shows a lobular, asymmetric mass. The adjacent mediastinal fat planes may be obliterated, and the tumours either are of homogeneous soft-tissue density or show multiple areas of contrast media enhancement interspersed with rounded areas of decreased attenuation caused by necrosis and haemorrhage. On MR, these tumours may demonstrate heterogeneous intensities with areas of high T2 signal intensity corresponding to degenerative cystic changes.

FIGURE 1 ■ Metastatic choriocarcinoma. A 23-year-old man presented with haemoptysis for 2 weeks. Chest CT demonstrates an anterior mediastinal mass of soft-tissue attenuation with slightly enhancing margins (A, B). (A) Mediastinal lymphadenopathy adjacent to the mass and (C) multiple pulmonary nodules dispersed throughout the lung are sites of metastases.

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