Multilocular peritoneal inclusion cyst with extensive xanthogranulomatous stromal changes: a differential diagnosis of cystic pelvic tumors in women.

This report presents an unusual case of multilocular peritoneal inclusion cyst with extensive xanthogranulomatous changes in the cyst stroma occurring in a 21-year-old woman. The multicystic tumor was found attached to the mesentery of the terminal ileum. Microscopically, the cystic spaces were lined by flattened to cuboidal cells, which displayed immunoreactivity for cytokeratin but not for factor VIII-related antigen. Large stromal areas contained cholesterol clefts, multinucleated foreign body giant cells, and accumulations of foam cells. The pathogenesis of this multilocular peritoneal inclusion cyst remains obscure. The patient is disease-free 10 years after surgery. The most important differential diagnosis to this case is mature cystic teratoma of the ovary with xanthogranulomatous changes.