Answer: Angiomyolipoma (AML) with atypia

Histology: none provided

Discussion: Classic renal angiomyolipoma is usually benign. The uncommon variant of renal epithelioid angiomyolipoma has been considered potentially malignant based on anecdotal case reports. However, a recent study evaluated otherwise classic AMLs with areas of epithelioid morphology. They found that atypical features can can be seen in 7-8% of otherwise classic AMLs (as is seen in our case). Despite adverse morphological features, the tumors in this study had a benign clinical outcome

Reference(s):
– Aydin et al. AJSP, Feb 2009.