Pancreatic Perivascular Epithelioid Cell Tumor (PEComa) Mimicking Neuroendocrine Tumor (NET): A Case Report.

Pancreatic perivascular epithelioid cell tumors (PEComas) are exceedingly rare mesenchymal neoplasms that often mimic neuroendocrine tumors (NETs) in their clinical and radiologic presentation, making preoperative diagnosis challenging. We report the case of a 67-year-old female with a 1.7 cm pancreatic body tumor initially suspected to be a NET. Preoperative chromogranin A levels were within the normal range. The patient underwent central pancreatectomy, and histopathological examination revealed a neoplasm composed of epithelioid cells arranged in sheets and cords within a hyalinized stroma. The tumor cells exhibited vesicular nuclei with distinct nucleoli and eosinophilic to clear cytoplasm. Although nuclear pleomorphism was present, no increased mitotic activity or tumor necrosis was identified. Immunohistochemistry was positive for HMB-45 and Melan-A, confirming the diagnosis of pancreatic PEComa. This report underscores the diagnostic challenge of pancreatic PEComas, which can closely resemble NETs, and highlights the importance of immunohistochemistry in establishing a definitive diagnosis.