Increased Mast Cell Density in Peritoneal Endometriosis Compared with Eutopic Endometrium with Endometriosis

PROBLEM: Factors regulating fibrosis in peritoneal endometriosis are poorly understood. We hypothesized that mast cell proteases may play a role in the process of fibrosis in peritoneal endometriosis. As the first step in examining the possible contribution of mast cells to fibrosis, we investigated their distribution in peritoneal endometriosis lesions according to their macroscopic appearance. METHOD OF STUDY: Mast cells were identified by immunohistochemistry using monoclonal antibody against mast cell tryptase on formalin-fixed, paraffin-embedded sections. Mast cell density (mean mast cell count per 0.13 mm2 of stroma) was measured using a computerized image analysis system. RESULTS: Mast cell density was significantly increased in black peritoneal lesions compared with red peritoneal lesions in endometriosis. CONCLUSIONS: Mast cells may be involved in the pathogenesis of peritoneal endometriosis.