Pancreatic Perivascular Epithelioid Cell Tumor: A Case Report and Literature Review

Perivascular epithelioid cell tumors (PEComas) are rare mesenchymal neoplasms, and primary pancreatic PEComas are exceptionally uncommon. Owing to their rarity, the prognostic significance of their pathological features remains unclear. We report a resected case of pancreatic PEComa and review the literature to further characterize its clinicopathological features.

A 72-year-old woman presented with a gradually enlarging, 63-mm hypervascular tumor in the pancreatic body. Contrast-enhanced CT and MRI demonstrated a well-circumscribed hypervascular mass with central hypoenhancement, suggestive of coagulative necrosis. Endoscopic US-guided tissue acquisition suggested acinar cell carcinoma because of weak trypsin positivity, and distal pancreatectomy with regional lymph node dissection was performed. Histopathological examination of the resected specimen revealed epithelioid and spindle cells that were positive for HMB45 and Melan-A and weakly positive for α-smooth muscle actin, leading to a diagnosis of pancreatic PEComa. The patient remained disease-free at 18 months after surgery. We also reviewed 26 previously reported cases of pancreatic PEComa and re-evaluated those with sufficient pathological information according to the Folpe criteria. Metastasis developed in 1 tumor classified as malignant and 1 classified as having uncertain malignant potential. Coagulative necrosis and increased mitotic activity appeared to be more frequent in the 2 metastatic cases; however, the small number of events precluded conclusions regarding their prognostic significance or the predictive performance of the Folpe classification.

Pancreatic PEComa should be considered in the differential diagnosis of hypervascular pancreatic tumors with atypical immunophenotypic findings. Additional immunohistochemical staining for melanocytic markers may facilitate an accurate preoperative diagnosis. The prognostic significance of individual pathological features and the applicability of the Folpe classification to pancreatic PEComa remain uncertain and require evaluation in additional well-documented cases with long-term follow-up.