Peritoneal "melanosis" associated with a ruptured ovarian dermoid cyst: report of a case with electron-probe energy dispersive X-ray analysis.

A case of peritoneal "melanosis" due to a ruptured left ovarian dermoid cyst is described. Histology showed that the dermoid contained gastric mucosa associated with ulceration, necrosis, and hemorrhage. The areas of pigmentation within the dermoid, omentum, and peritoneal cavity were due to collections of heavily pigment-laden macrophages. The pigment lacked the histochemical features of either melanin or hemosiderin, but electron-probe energy dispersive x-ray analysis showed that the pigment contained a high concentration of iron. It is postulated that peptic ulceration with hemorrhage is the most likely source of the pigment and that the peritoneal pigmentation is secondary to spillage of the contents of the dermoid cyst.