Answer: Acinar cell carcinoma

Histology: The aspirate is cellular and shows cohesive fragments of a monomorphic population of cells. The fragments are crowded and disordered, and the cells have round nuclei that are often eccentrically placed, increased N/C ratios, and granular cytoplasm. No ductal elements were appreciated. The tumor cells show acinar arrangements (best seen in cell block, image 4), and in the surgical specimen:

Discussion: Similar to case 1, the fact that only one cell type is present indicates that this is a neoplastic process and again the main considerations in this case are islet cell tumor and acinar cell carcinoma. Without immunohistochemical stains that distinction would be extremely difficult on cytomorphologic grounds alone. The acinar architecture seen in the cell block is helpful for correct classification.

Acinar cell carcinoma of the pancreas account for less than 5% of pancreatic malignancies and have a slight male predominance. The tumors can have acinar or solid growth patterns and tend to have round to oval nuclei that are relatively uniform. Immunohistochemical stains for antitrypsin, chymotrypsin, amylase, and lipase are frequently positive. The clinical syndrome of disseminated fat necrosis, polyarthralgia, and eosinophilia has been associated with these tumors and is a consequence of secrection of lipase or other digestive enzymes. The prognosis is poor with most patients dying within a few months of diagnosis.