OBJECTIVE: To evaluate cytologic differences between primary and metastatic specimens of colonic adenocarcinoma. STUDY DESIGN: Fifty colonic brushings of primary adenocarcinoma of the colon and 50 specimens of metastatic colonic adenocarcinoma were examined. The latter included fine needle aspirates of lung, liver and other sites and bronchial brushings. RESULTS: In contrast to primary colonic adenocarcinomas, which typically showed large, hyperchromatic nuclei, many cases of metastatic colonic adenocarcinoma showed nuclei with fine, delicate chromatin and distinct nuclear membranes. Often occurring in conjunction with those two features were prominent nucleoli and thin internuclear pseudo-channels separating adjacent nuclei. Other features noted in occasional metastatic cases but only rarely in primary specimens were small tumor cell size, uniformity and cohesiveness. CONCLUSION: The features delicate chromatin, distinct nuclear membranes and prominent nucleolus, with the occasional presence of thin internuclear pseudochannels, may be viewed Its constituting a secondary cytologic pattern of colonic adenocarcinoma to complement the basic classic pattern of elongated cell shape; hyperchromatic, cigar-shaped nuclei; nucleoli; molding of nuclei; palisaded or glandular arrangement; and necrosis. Varying states of preservation and degeneration may explain many of these differences.
