What proportion of mature teratomas contain fat?
50%. Fat-fluid levels are more specific but much less frequent.
In which decade do these masses most commonly present?
The 2nd decade. They account for only 5% of prevascular masses in the over 50 age group.
There is a large ovoid anterior mediastinal mass measuring 11 x 9 x 9 cm (transverse x anteroposterior x craniocaudal) to the left of the midline, heterogenous in appearance with lobulated fat density components and several small calcific foci. Marked internal vascularity demonstrated.
The mass is anterosuperior to the heart with pronounced mass effect upon the right ventricular outflow tract (RVOT), pulmonary trunk and left main pulmonary artery (LPA). RVOT orifice is narrowed to 7 x 31 mm. Ostial LPA is narrowed to 17 x 3 mm.
The tracheobronchial tree is patent, however there is marked mass effect involving the left main bronchus (narrowed to 3 mm AP). Close relationship between the inferior mass and the RVOT pericardium with loss of the normal fat plane. There is a pericardial effusion visualised at the cardiac apex. No nodularity of the pericardium identified.
Left lower lobe bronchial thickening with tree in bud nodularity adjacent in the medial basal segment suggests inflammatory change, possibly due to aspiration. No focal pulmonary lesion or mass. No focal filling defect to suggest pulmonary embolus on this non dedicated imaging.
Partially obscured two small ovoid solid structures adjacent to the mass superiorly and appear hyperdense possibly representing lymph nodes and measure 16 mm and 12 mm short axis respectively. No evidence of further mediastinal or axillary lymphadenopathy. No abnormalities of the partially imaged abdomen.
Features are suspicious for germ cell tumour/mediastinal teratoma, differentials include thymolipoma.