Clear cell variant of solid pseudopapillary neoplasm of pancreas diagnosed by fine needle aspiration: A case report and review of the literature.

Solid pseudopapillary neoplasm (SPN) of the pancreas is a rare tumor of uncertain malignant potential, predominantly affecting young adult females. We report a case of clear cell variant of SPN, which was diagnosed by fine needle aspiration biopsy. The aspirate was highly cellular and exhibited delicate branching papillary structures with central capillaries covered with several layers of plasmacytoid tumor cells. Acinar and rosette-like formations, as well as single neoplastic cells were also observed. An unusual cytologic feature was the presence of large, clear cytoplasmic vacuoles. The diagnosis of SPN was confirmed by characteristic immunocytochemical staining pattern including nuclear staining for β-catenin, cytoplasmic staining for vimentin and lack of reactivity for cytokeratin.