Distinction of intestinal and diffuse types of gastric adenocarcinoma on brush cytology

Objective: To distinguish between the intestinal and diffuse types of gastric adenocarcinoma on brush cytology (BC).

Study design: Brushing smears and biopsy samples obtained at endoscopic examination from 32 patients with clinically or radiologically suspected gastric malignancy were included in the study. Cytologic smears were examined by 2 cytopathologists, using predetermined criteria to arrive at a consensus diagnosis. A meticulous attempt was made to distinguish between the 2 types of gastric adenocarcinoma. Cytologic diagnoses were correlated with the histologic diagnoses.

Results: Twenty-one cases (65.6%) were concordant between BC and endoscopic biopsy (EB) with respect to sub-typing. Two (6.2%) cases reported as 'poorly differentiated adenocarcinoma' on BC turned out to be 'diffuse type'. Three cases (9.4%) reported as 'diffuse type' on BC were 'intestinal type' on EB. Two of these discordant cases had intestinal metaplasia on BC, which should have suggested 'intestinal type' of adenocarcinoma on BC. Three cases (9.4%) were false positive. On review, 2 of these false-positive cases showed cytologically convincing malignant cells, the third case was misinterpreted as diffuse type of adenocarcinoma due to reactive glandular cells entangled in the mucoid background. Three (9.4%) EB were non-representative with only superficial mucosa; BC diagnosis in these 3 cases was intestinal type of adenocarcinoma.

Conclusion: Although, overlapping cytomorphology between the intestinal and diffuse types of gastric adenocarcinoma can cause diagnostic problem; with a meticulous cytomorphologic approach, it is possible to accurately distinguish between the 2 types in a considerable number of cases.