Perivascular Epithelioid Cell Tumor (PEComa) of Pancreas Diagnosed Preoperatively by Endoscopic Ultrasound-Guided Fine-Needle Aspiration: A Case Report and Review of Literature.

Perivascular epithelioid cell tumors (PEComas) of the pancreas are extremely rare mesenchymal tumors and to our knowledge, only 17 cases have been reported in the English literature to date. We report our experience with a new case of primary pancreatic PEComa diagnosed preoperatively by endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) complemented by tissue cell block and immunohistochemistry. The patient was a 54-year-old female whose chief complaint was intermittent severe right upper quadrant abdominal pain. Computed-tomography (CT) imaging revealed a mass between the head and the body of the pancreas. EUS-FNA smear preparation was obtained but was nondiagnostic. However, examination of the tissue cell block showed sheets of epithelioid cells with abundant eosinophilic cytoplasm and immunohistochemistry studies revealed positivity for both melanocytic (HMB-45 and Melan-A) and smooth muscle markers (actin and desmin). A diagnosis of PEComa was made and an uncomplicated middle pancreatectomy was performed. Our case and review of the literature demonstrates that EUS-FNA complemented with tissue cell block increases cellular yield, improved preoperative diagnostic accuracy, and may assist the surgeon in planning conservative surgical management. Diagn. Cytopathol. 2017;45:59-65.