Atypical pleomorphic epithelioid angiomyolipoma localized to the pelvis: a case report and review of the literature.

Aims: Angiomyolipoma is the most common mesenchymal tumour of the kidney. It has been reported in several other sites outside the kidney, mainly in the liver. We report the first case of atypical pleomorphic angiomyolipoma in a man, arising from the pouch of Douglas and extending to the entire abdominal cavity.
Methods: A 17-year-old man underwent a complete resection of a giant abdominopelvic mass. The tissue was formalin fixed and paraffin embedded and 4 micro m thick histological sections were stained with haematoxylin-eosin. Immunohistochemical stains for HMB-45, smooth muscle actin, vimentin, calponin, S100 and desmin were performed. Sections for electron microscopy were also prepared.
Results: Microscopic examination revealed a neoplasm composed of pleomorphic epithelioid cells with atypical features, immunoreactive for HMB-45, MART-1, actin, vimentin and calponin, while S100 protein and desmin stains were negative. Ultrastructurally, the tumour cells showed prominent nucleoli, vacuolated cytoplasm, and some premelanosomes. A diagnosis of atypical pleomorphic epithelioid angiomyolipoma was then made.
Conclusions: To date five patients with abdominal epithelioid angiomyolipoma have been described in the literature. All were women. Three of the five patients reported developed metastasis, while our patient is still free of disease at 16 months of follow-up. Clear prognostic pathological features have not been identified.