Large angioleiomyoma, rich of mast cell and sex hormone receptor expression

Background Angioleiomyoma is a rare benign solitary tumor, arising from the vascular smooth muscle. This tumor usually occurs in the subcutis of extremities, uncommonly in abdomen, often presents as a small (<2 cm) and is treated with excision. Case We report an extremely rare case of unusually large angioleiomyoma, first diagnosed as an ovarian tumor with some malignant possibilities by diagnostic imaging. We resected 1.7 kg of tumor from the extra-peritoneal cavity in the lower abdomen. Histological study revealed that this case’s angioleiomyoma had abundant mast cells and sex hormone receptor expression. Conclusion This angioleiomyoma is not an obvious malignant tumor because of low mitosis, coagulative necrosis and cellular atypia. However, it seems to have low potential malignancy, because it has massive size, marked degeneration and abundant mast cells. There are some possibilities that sex hormones are related with the growth and degeneration of this case’s tumor, because those receptors are strongly expressed in the nucleus of tumor cells.