Fine needle aspiration cytomorphology of mucinous nonneoplastic cyst of the pancreas

OBJECTIVES: Fine needle aspiration (FNA) cytomorphology of mucinous nonneoplastic cyst (MNNC) of the pancreas has not been described. METHODS: Nineteen of 24 patients with surgically diagnosed MNNCs had presurgery endoscopic ultrasound (EUS)-FNA biopsy. The FNA cytomorphology was retrospectively evaluated. Cyst fluid carcinoembryonic antigen and amylase concentrations were measured. RESULTS: Endoscopic US-FNA diagnoses ranged from unsatisfactory to suspicious for adenocarcinoma. Endoscopic US-FNA cytologic findings showed cuboidal or columnar cells arranged in flat 'honeycomb' sheets/nests (100.0%), papillary architecture (10.5%), acini formation (10.5%), 3-dimensional cluster (5.3%), abundant single cell pattern (5.3%), goblet cells (17.4%), and delicate or vacuolated (60.9%) cytoplasm variable in amount. Nuclei were round or oval and small to slightly enlarged with 1 or 2 inconspicuous nucleoli, fine granular chromatin, and smooth nuclear contour (irregular in 1 case). Nuclear grooves (43.5%) and nuclear pseudoinclusions (26.1%) were identified. Most cases showed thin mucin and thick mucin in 4 cases. Stroma was seen in 4 cases (17.4%). Degenerated cells/necrotic material and macrophages were also seen. Carcinoembryonic antigen ranged from 75.2 to 5,488 ng/ml and amylase from 19 to 28,478 U/L. CONCLUSIONS: Recognition of FNA cytomorphology of MNNC and valuable of carcinoembryonic antigen and amylase levels in cyst fluid is critical in clinical evaluation of pancreatic cysts.