Cytomorphology of gastric and duodenal epithelium and reactivity to B72.3: A baseline for comparison to pancreatic lesions aspirated by EUS-FNAB

Abstract

Endoscopic ultrasound-guided fine-needle aspiration biopsy (EUS-FNAB) has become a widely used method of pre-operatively evaluating pancreatic masses. This technique introduces gastrointestinal contamination into the specimen, which poses a diagnostic pitfall. The cytomorphologic features of these contaminants have not been fully characterized. The current study was designed to systematically document the cytomorphology of gastric and duodenal epithelium on fixed and air-dried smears, as well as ThinPrep (TP) preparations, and to assess the reactivity of the epithelial cells to the tumor marker B72.3 so as to establish a baseline for future comparative studies with EUS-FNAB of the pancreas. Air-dried and fixed smears and TP specimens were obtained using a cytobrush from gastric (GM) and duodenal (DM) mucosa from 14 Whipple specimens. Cytologic features of cell architecture, cellular features and smear background were analysed. Immunocytochemical staining with B72.3 was performed in 10/14 cases. Mucin was present in all preparations except one case from the duodenum. It was consistently present as isolated thick to thin clumps but never as diffuse 'colloid-type' mucin; it was most prominent on air-dried smears, and most abundant from the GM. Epithelial cells were admixed with mucin, but degenerated cells and inflammation were not present within the mucin. Mucin on TP appeared as fragmented wisps of pale blue staining material. Background inflammation and debris were not significant findings. The epithelial cells were arranged in large and small monolayered sheets. Smaller groups were more common from GM on smears and more abundant on TP than smears. Luminal edges (DM>GM) were a prominent feature, with a brush border noted in DM. The nuclei of GM and DM were round, evenly spaced and without atypia, and dense, non-vacuolated cytoplasm was the rule, with the exception of goblet cells and occasional gastric foveolar cells noted in one case. In both GM and DM, B72.3 stained goblet cells with a strong, coarsely granular pattern and stained epithelial cells focally in a finely granular, punctate, perinuclear distribution; mucin also stained strongly in all cases. These baseline characteristics provide a template for assessing mucin and epithelial GM and DM contamination on pancreatic EUS-FNAB specimens.

Prospective analysis of atypical epithelial cells as a high‐risk cytologic feature for malignancy in pancreatic cysts

“…12,16,17 The difficulty in interpreting degenerated cells in cyst fluid, coupled with the concern for over interpretation of gastrointestinal contamination, typically results in a conservative cytologic interpretation. 18,19 In addition, HGD and malignant cells associated with invasive carcinoma often have the same degree of cytologic atypia. Therefore, many cytopathologists-especially cytopathologists who have little experience interpreting pancreatic cyst fluids-elevate the threshold for a malignant interpretation and may undervalue the significance of small clusters of cells with atypia but no overt features of malignancy.…”

Can outcome of pancreatic pseudocysts be predicted? Proposal for a new scoring system

“…[20] Only complicated cases with gastrointestinal epithelial and mucin contamination, particularly from the stomach, should include cystic lining epithelial cells. [19,21,22] Van der Waaij et al analyzed 12 studies and demonstrated that CEA levels below 5 ng/mL present a specificity of 95% for pseudocyst formation. [18] Biliary complications of PPs manifest as obstructive jaundice, requiring intervention until the pseudocyst resolves.…”

Pancreatic cysts

“…10). 67 Atypical epithelial cells are most critical to recognize, as we have shown that these cells even when very scant correlate with an increased risk of malignancy. 12,62,79 A neoplastic mucinous cyst with a cyst lining of moderate or higher dysplasia may produce atypical epithelial cells in small, tight, bud-like clusters or singly with increased nuclear to cytoplasmic ratio, irregular nuclear membranes, and cytoplasm with or without mucin (Fig.…”

“…66 Gastrointestinal epithelial and mucin contamination, particularly from the stomach, can lead to a misdiagnosis of a mucinous cyst. 65,67,68 Special stains for mucin that show only scant amounts of mucin-positive fluid should not be interpreted as evidence of a mucinous neoplasm, as this finding may well represent gastrointestinal contamination. Cyst fluid analysis with an elevated amylase in the thousands and low CEA level (<192 ng/mL) supports the interpretation of a pseudocyst.…”

“…67,68 Accurate distinction between carcinoma in situ and invasive carcinoma has not been extensively investigated. In our experience, background cellular, coagulative-type necrosis (not just a few degenerated cells in mucin) distinguished noninvasive from invasive tumors.…”