Malignant renal epithelioid angiomyolipoma associated with abdominopelvic hydatid cysts: a case report

The World Health Organization defines epithelioid angiomyolipoma as a potentially malignant mesenchymal neoplasm characterized by proliferation of predominantly epithelioid cells and as closely related to the triphasic (classic) angiomyolipoma. It can be benign, potentially aggressive or malignant. The pathologist's role is crucial in making a positive diagnosis, providing appropriate patient management and assessing prognosis. In this report, we present a case of a patient with an epithelioid angiomyolipoma and hydatid cyst association. To the best of our knowledge, such an association has not been reported previously in the literature.

A 70-year-old Arabian woman presented to our hospital with a 6-month history of a right lumbago and weight loss. Computed tomography objectified a mid-right renal tumor, several locoregional lymph nodes and four abdominopelvic cystic formations. The patient underwent a right nephroureterectomy and removal of abdominal and pelvic masses. Histologically, the tumor corresponded to a proliferation of large eosinophil cells, polygonal or ovoid, with epithelial appearance, and associated with thickened, hyalinized vessel walls, fat cells and bundles of smooth muscle cells. Mitoses were estimated at 2 per 50 high-power fields. In immunohistochemical study, epithelioid tumor cells expressed S-100 protein and Melan-A. The diagnosis of malignant epithelioid angiomyolipoma was made. The wall of the abdominopelvic cysts was eosinophilic and lamellar, corresponding to the cuticular membrane of hydatid cysts.

In our patient, careful histological examination and immunohistochemical study allowed us to make the correct diagnosis of angiomyolipoma in its malignant form. The association with hydatid cysts is what makes our case original.