Cytologic features of squamous cell carcinoma in situ involving endocervical glands in endocervical cytobrush specimens.

Clinical usage of the cytobrush has led to an increase in cellular yield on endocervical cell samples. In cases of squamous cell carcinoma in situ (CIS) involving endocervical glands, clusters of abnormal cells on endocervical smears can be confused with well-differentiated adenocarcinoma in situ (AIS). The purpose of this retrospective three-year study (January 1988 through December 1990) was to evaluate the cellular features of endocervical gland involvement by CIS on cell samples obtained with the cytobrush. Of the 45 cases of CIS diagnosed on cytology, 25 (56%) had histologic correlation and form the basis of this study. In 10 (40%) of the 25 cases two distinct cell patterns were noted. Pattern A was composed of round to oval clusters of abnormal cells with smooth cell borders. Cells at the periphery were flattened, while those within the center had a spindling or whorling arrangement. The cells showed an increased nuclear/cytoplasmic ratio and contained hyperchromatic nuclei and granular chromatin. Nucleoli were not discernible. Pattern B consisted of sheets of columnar cells with peripheral palisading and nuclear pseudostratification, findings that might be interpreted as AIS. The cellular characteristics were similar to those of pattern A. Histologically all cases (10 cervical cones) showed transformation zone and/or endocervical canal involvement by CIS with extension into endocervical glands. In 8 (32%) of the 25 cases, neither cell pattern was present on cytology. In 7 of these cases (87.5%), 7 cervical cones did not show CIS within endocervical glands; supporting findings for patterns A and B represented gland involvement by CIS. In the remaining 7 cases (28%), 6 (85.7%) showed pattern A, and 1 (14.3%) showed pattern B; of these, 5 (71%) showed CIS within endocervical glands (5 cervical cones). Histologically, none of the 25 cases showed endocervical AIS. Endocervical gland involvement by CIS has characteristic cell patterns on endocervical cell samples obtained with the cytobrush that permit the distinction from well-differentiated AIS.