Leiomyomatosis peritonealis disseminata coexisting with endometriosis within the same lesions: a case report with review of the literature.

Leiomyomatosis peritonealis disseminata (LPD) is an extremely rare condition, which is characterized by the presence of multiple peritoneal and subperitoneal nodules composed of bland smooth muscle cells. Albeit extremely rare, coexistence of endometriosis within LPD lesions has also reported. Herein, we report the seventh documented case of LPD coexisting with endometriosis within the same lesions and review the pathogenesis of this lesion. A 42-year-old Japanese female presented with an abdominal tumor. Computed tomography revealed a tumorous lesion in the right ovary and multiple small nodules in the abdominal cavity. Under a clinical diagnosis of ovarian cancer with peritoneal dissemination, resection of these lesions was performed. Histopathological study of the disseminated peritoneal nodules revealed proliferation of interlacing bundles of spindle cells with eosinophilic cytoplasm and bland cigar-shaped nuclei. Mitotic figures were hardly seen. The peritoneal nodules of the rectum had cystic cavities within the spindle cell bundles, and endometrial glands and stroma were present around the cystic cavities and spindle cells. The resected tissues of the ovary and cecum showed the same histopathological features. Accordingly, a diagnosis of LPD with endometriosis within the same lesions was made. A possible origin of LPD is thought to be the submesothelial multipotential stem cells, also referred to as the secondary müllerian system. The presence of endometrial tissues within LPD lesions, as seen in the present case, also support this hypothesis because endometrial tissues are also derived from the müllerian system.