Cystic teratoma of the diaphragm which mimicked soft tissue lipoma

We report a case of cystic teratoma of the diaphragm that was considered to be a soft tissue lipoma by the preoperative examination. A magnetic resonance imaging revealed an 8×8 cm well-demarcated, homogeneous mass. On T1- and T2-weighted imaging, the mass was isointense to fat. On the fat-suppressed imaging, the signal from the mass was reduced to the same degree as subcutaneous fat. We performed marginal excision. The tumor contained a large number of hairs and oily liquid; and it was connected to the diaphragm.