CYTOKERATIN-20 AND CYTOKERATIN-7 IN THE DIFFERENTIAL-DIAGNOSIS OF METASTATIC CARCINOMA IN CYTOLOGIC SPECIMENS

A se,ies of 33 tumor cases (13 fine-needle aspirates and 20 effusion s pecimens) were evaluated for the expression of two cytokeratin (CK) su btypes; CK 20, expressed primarily in tumors of the GI tract, mucinous ovarian tumors and transitional cell carcinomas, and CK 7, found chie fly in non-GI tract adenocarcinomas, including breast and lung CK 20 e xpression was demonstrated immunocytochemically in seven of seven meta static colon and two of three metastatic transitional cell carcino,nas tested CK 20 was absent in all metastatic carcinomas of breast ovary lung, and uterus examined (23 cases). Anti-CK 7 stains were negative i n four of six metastatic colonic carcinomas with equivocal results in the remaining two cases. Metastatic lung, breast, and ovarian carcinom as were strongly positive for CK 7. This study demonstrates that the c ombined use of anti-CK20 and anti-CK 7 antibodies is highly sensitive and specific for metastatic colonic adenocarcinoma in cytologic materi al and thus could play an important role ill distinguishing this entit y from other common primary carcinomas. (C) 1997 Wiley-Liss, Inc.