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

TL;DR

A rare pancreatic tumor called PEComa was mistaken for a neuroendocrine tumor before surgery, highlighting the need for detailed testing to confirm the diagnosis.

Contribution

This case report adds to the limited literature on pancreatic PEComas and emphasizes the role of immunohistochemistry in accurate diagnosis.

Findings

A 67-year-old female was diagnosed with a pancreatic PEComa after surgery and histopathological analysis.

Immunohistochemistry confirmed the tumor was a PEComa, not a neuroendocrine tumor.

The tumor lacked increased mitotic activity and necrosis, supporting a benign or low-grade malignancy.

Abstract

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.

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