Congenital quadrigeminal lipoma with osteocartilagenous element. A case report.

A case of congenital tectal lipoma found incidentally at an autopsy is reported. This female fetus was a product of pregnancy termination at 24 weeks of gestational age after sonographic detection of hydrocephalus. Autopsy revealed a small mass in the periaqueductal portion. The mass was composed of adipose tissue, cartilage, and mature bony tissue with hematopoiesis. The resultant diagnosis was tectal lipoma with osteocartilagenous element. It is uncertain whether the lesion represents a teratoma or hamartoma or mesenchymal metaplasia. The osteocartilagenous component suggests the latter.