Renal angiomyolipoma with epithelial cyst

Abstract

Angiomyolipoma with epithelial cysts (AMLEC) is a recently described entity and is an uncommon subtype of kidney angiomyolipomas. AMLEC is a benign entity but usually masquerades a renal cell carcinoma on imaging examination. AMLEC has a distinct histological and immunohistochemical staining pattern, which helps in the pathological diagnosis. We present a rare case of AMLEC in a 26-year-old female, which was provisionally diagnosed as renal cell carcinoma on radiology. We also summarize the differential diagnosis of this rare variant, its characteristic features, and a review of the literature.

Keywords: Angiomyolipoma; Diagnosis, Differential; Kidney; Neoplasms; Nephrectomy.

Figure 1. A – Gross view of the surgical specimen showing large solid grey white mass with entrapped cystic spaces; B – Photomicrograph showing multiple variable sized cystic spaces (H&E, 40X); C – Photomicrograph showing hypercellular stroma along with adipocytic aggregates (H&E, 40X); D – Photomicrograph showing epithelial cysts lined by cuboidal to hobnailed cells (H&E400X).

Figure 2. Photomicrographs of the tumor. A – Epithelium lining the cystic spaces showing intense pancytokeratin staining (100X); B – Compact ovarian like stroma showing nuclear ER staining (400X); C – Vessel walls and few stromal cells highlighted by SMA (100X); D – SMA highlighting blood vessel (400X).

Figure 3. Photomicrographs of the tumor. A – Epithelium lining the cystic spaces expressing PAX-8 (100X); B – Stromal cells showing diffuse positivity for Melan A (400X).