Case History
A 36-year-old male had a nonresectable pancreatic mass. There were bilateral lung lesions suspicious for metastasis. No renal lesion was identified.
What is the diagnosis?
- Melanoma
- Clear cell renal cell carcinoma
- Carcinoma
- Pecoma
Answer: D. Perivascular epithelioid cell tumor
Perivascular epithelioid cell tumor (PEComa) is an extremely rare mesenchymal tumor. FNA shows dispersed cells with eosinophilic to clear cytoplasm. The nuclear are oval with prominent nucleoli. This is a very difficult case and many differentials are on the list such as RCC, melanoma, HCC, GIST, and acinar cell carcinoma. The following stains are negative: CK7, CK20, Pancytokeratin, EMA, CA19-9, Chromogranin, synaptophysin, chromotrypsin, trypsin, CD10, RCC, OCT3/4, Sall4. Glypican-3, Hep-par1, arginase, inhibin, SF-1, Pax8, S100, Sox10, CD117. Following are positive: Vimentin, HMB-45.
Case contributed by: Shoujun Chen, M.D., Ph.D., Cytopathology Pathology Fellow, UAB Pathology