Anatomic Pathology: Cytopathology

1345) These photomicrographs depict material obtained from an endoscopic ultrasound-guided (EUS) fine needle aspiration biopsy of a mass in the head of the pancreas in a 74-year-old man. They MOST likely represent:

• Cells derived from small intestinal epithelium usually appear as flat sheets of cohesive, uniform cells in a honeycomb arrangement. Small intestinal epithelium may be recognized by the presence of goblet cells, as depicted in the photomicrograph.

• In contrast, cytomorphologic features of aspirates of pancreatic adenocarcinoma include increased cellularity; sheets of disorganized cells (“drunken” honeycomb) with overlapping, pleomorphic nuclei with irregular nuclear membranes; coarse and irregular chromatin; and increased N:C ratios. Three-dimensional clusters, single malignant cells, and mitotic figures may also be present.

• Gastric epithelium may be virtually indistinguishable from benign pancreatic ductal epithelium. Goblet cells usually are not seen.

• Smears from low grade mucinous cystic neoplasms (MCN) are grossly gelatinous and usually hypocellular and show flat, usually organized, sheets of bland mucinous epithelium in a background of abundant thick mucin. The cells are columnar, with mucin-filled cytoplasmic vacuoles and basally located nuclei.

• Differentiating benign gastric and intestinal mucosal epithelial cells from mucinous neoplasms can be difficult. One helpful feature is the presence of thicker and more abundant mucin in association with MCN. Benign intestinal epithelium may be very similar to benign pancreatic ductal epithelium; however, pancreatic ductal epithelium has no goblet cells.

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