[Solid pseudopapillary neoplasms. Enigmatic entity with female preponderance]

Solid pseudopapillary neoplasms (SPN) of the pancreas represent a special tumor entity, both morphologically and biologically. They form large solitary tumors that occur predominantly in young women. Histologically, they show solid, pseudopapillary, and pseudocystic patterns. The tumor cells are monomorphous and typically express vimentin, neuron-specific enolase, nuclear beta-catenin, and the progesterone receptor. Complete resection cures the tumor in about 90% of the cases. However, because recurrences and even metastases may occur in a small number of cases, SPN are classified as low-grade malignant tumors. Predicting malignancy histologically is not yet possible. The most important differential diagnosis to consider is neuroendocrine tumor of the pancreas. The etiology and pathogenesis of SPN are obscure.