Peritoneal melanosis combined with serous cystadenoma of the ovary: a case report and literature review.

Benign peritoneal melanosis is extremely rare and traditionally occurs in association with ovarian dermoid cysts, but rarely with peritoneal cyst, enteric duplication cyst or gastric triplication. The pathogenesis of peritoneal melanosis, in particular, the origin of the pigment-producing cells is unclear. We describe a case of peritoneal melanosis that was associated with ovarian serous cystadenoma in a young woman. Ovarian serous cystadenoma has not been previously described as a combined lesion of peritoneal melanosis. Based on the extremely rare incidence of this lesion and heterogeneous combined lesions, the possibility of an incidentally found, coexisting lesion couldn't be excluded. Here, we suggest that peritoneal mesothelial cells pinched off during the developmental period might be a source of pigment-producing cells.