CLEAR-CELL SUGAR TUMOR OF THE PANCREAS - A NOVEL MEMBER OF THE FAMILYOF LESIONS CHARACTERIZED BY THE PRESENCE OF PERIVASCULAR EPITHELIOID CELLS

We report a unique, previously unreported pancreatic tumor occurring i n a 60-year-old woman who was preoperatively diagnosed on cytoaspirati on as having clear cell carcinoma. The resected tumor consisted of a p opulation of large epithelioid cells with clear or eosinophilic, granu lar cytoplasm, rich in glycogen, with nuclear pleomorphism and no mito tic activity. In spite of the epithelioid appearance, the tumor cells were negative for epithelial (CAM 5.2, KL1, AE1-AE3), endocrine (neuro n-specific enolase [NSE], chromogranin A), and acinar (lipase, amylase ) markers and positive for actin and melanogenesis-related marker HMB 45. Ultrastructurally, the neoplastic cells showed membrane-bound gran ules; no evidence of either epithelial or melanocytic differentiation was present. These morphophenotypic features have never been reported in a pancreatic tumor and overlap those of clear cell ''sugar'' tumor of the lung. The same morphophenotypic features are observed in a fami ly of lesions characterized by the presence of the perivascular epithe lioid cell that also includes lymphangiomyomatosis and angiomyolipoma. The present case may be considered a novel member of this family of l esions. We propose this new entity be named clear cell ''sugar'' tumor of the pancreas.