Brush cytology in the diagnosis of colonic neoplasms

During a three‐year period (1986–1988), 234 colonic brush specimens were received in the authors' laboratory. Nine samples (4%) were deemed unsatisfactory for evaluation because of inadequate cellularity and/or poor fixation. In 11 cases concomitant or follow‐up histologic specimens were not available. The remaining 214 specimens included 82 malignant neoplasms, 88 neoplastic polyps (adenomas), and 44 nonneoplastic lesions. Sixty‐seven (82%) of malignant neoplasms were correctly diagnosed by brush cytology. Three cases of adenoma with severe dysplasia or in situ carcinoma were diagnosed as adenocarcinoma by cytology. No false‐positive diagnoses were made of nonneoplastic lesions. Brush cytology was found to be a more sensitive technique in the diagnosis of colon cancer than endoscopic biopsy (82% and 74% sensitivity, respectively). The combination of the two techniques increased the sensitivity to 90% and improved the overall accuracy of the test. Seventy‐one (82%) of the colonic adenomas were correctly diagnosed by cytology. Brush cytology is a convenient, safe, and accurate technique which should be used concurrently with endoscopic biopsy or polypectomy.