Solid and Pseudopapillary Tumor of Pancreas
Solid area composed of polygonal, monomorphic cells admixed with thin-walled blood vessels. True gland formation is not seen. A tumor with a predominant solid pattern may resemble Acinar Cell Carcinoma (which is seen predominantly in males and is trypsin and chymotrypsin positive) and Well Differentiated Pancreatic Neuroendocrine Tumor (keratin and chromogranin A positive). SPT is immunoreactive for vimentin, CD10, CD56, synaptophysin, alpha-1- antitrypsin, progesterone receptors, and shows nuclear accumulation of beta catenin. Almost all (90-100%) have a somatic point mutation in the beta-catenin gene.