Primary mediastinal germ cell tumour and acute monocytic leukaemia occurring concurrently in a 15-year-old boy

This report describes the case of a 15-year-old boy who presented with a primary mediastinal germ cell tumour and while receiving chemotherapy developed an acute monocytic leukaemia. The occurrence of these conditions simultaneously is extremely rare, and the possible shared aetiology is discussed. Also, the role of the chromosome marker i(12p) in the diagnosis of germ cell tumours is examined.