Cytological appearance of pancreatic cystosis on fine-needle aspiration.

A 22-year-old Caucasian male with cystic fibrosis and recently diagnosed insulin-dependent diabetes mellitus underwent magnetic resonance imaging (MRI) and was found to have multiple cystic lesions in the pancreas. Endoscopic ultrasound evaluation revealed multiple macro- and microcystic components without mural nodules. One of the cysts in the body of the pancreas was in clear direct communication with the nondilated main pancreatic duct. Fine-needle aspiration (FNA) of two cysts was performed and showed foamy macrophages and rare ductal as well as acinar cells. Cell blocks showed nonpolarizable pink crystalloid material and small nonlaminated concretions consistent with inspissated secretions. Special stains for chymotrypsin and trypsin highlighted the acinar cells. Periodic acid Schiff, with and without diastase, was negative. Biopsy of the cyst wall showed ductal epithelial cells with underlying fibrotic stroma. This is the first description of the FNA appearance of pancreatic cystosis. We discuss the cytological differential diagnosis of cystic lesions of the pancreas and the biochemical as well as imaging findings used to arrive at the diagnosis.