CD56 reactivity in small cell carcinoma of the uterine cervix.

Small cell carcinoma (SCC) of the uterine cervix, like its pulmonary counterpart, is a rare but distinctive neoplasm that should be separated from nonendocrine carcinomas because of its highly aggressive clinical course and response to chemotherapy and irradiation. CD56 (neural cell adhesion molecule) has recently been shown to be the best marker for the diagnosis of pulmonary SCC. In this study, we assessed the sensitivity and specificity of CD56 in the diagnosis of SCC of the uterine cervix compared with those of chromogranin and synaptophysin. Twenty-two (88%) of 25 SCCs of the uterine cervix labeled with CD56 in a predominantly membranous and diffuse pattern, whereas 16 of 25 (64%) stained with synaptophysin in a predominantly diffuse pattern and 8 of 25 (32%) showed predominantly focal immunoreactivity for chromogranin. In contrast, 3 of 21 (14%) moderately to poorly differentiated squamous cell carcinomas and 1 of 16 (6%) moderately differentiated adenocarcinomas showed focal immunoreactivity for CD56. Although not specific, CD56 seems to be the most sensitive marker for the diagnosis of SCC of the uterine cervix. Moreover, its diffuse reactivity reduces the possibility of obtaining negative results in small biopsy samples.