[Solid and papillary epithelial tumor of the pancreas: cytologic and histologic features]

Cytologic and histologic features in a case of solid and papillary epithelial neoplasm (SPEN) of the pancreas in a 34-year-old female are presented. In the fine-needle aspiration material, there was a predominance of pseudopapillary fragments with delicate fibrovascular core lined with one or more layers of uniform tumor cells with clear cytoplasm. There were also acinar-like or rosette-like structures and dispersed tumor cells. Tumor cells had small, round to oval nuclei, with finely granular chromatin and inconspicuous nucleolus. Rarely, nuclear grooves were present. Mitoses were not seen. Histologically, the encapsulated tumor was predominantly solid, with focal pseudocystic and pseudopapillary areas; foreign body granulomas were focally present. Tumor cells were small and uniform with clear cytoplasm. Mitoses were extremely rare. Immunohistochemically, the tumor cells revealed diffuse positivity of vimentin, and focal positivity for alpha 1-antitrypsin and CD68. No immunoreactivity for chromogranin, synaptophysin, cytokeratin, HMB 45, estrogen and progesterone receptors was found. In differential diagnosis, it is important to distinguish SPEN mainly from mucinous tumors of the pancreas, microcystic adenoma and pseudocysts, but also from endocrine tumors of the pancreas, acinic cell carcinoma, renal cell carcinoma, adrenal cortical adenoma and primary extrapulmonary sugar tumor.