Endocervical adenocarcinoma in situ: an analysis of cellular features

Cytologists increasingly encounter atypical endocervical cells, because of the increasing incidence of endocervical adenocarcinoma and the use of improved endocervical sampling devices. These atypical endocervical cells can cause diagnostic problems, especially in recognizing adenocarcinoma in situ (AIS) and distinguishing it from a variety of nonneoplastic changes. We analyzed 33 cervical smears from 22 patients with confirmed AIS and compared these to 19 cervical smears from 17 patients having atypical endocervical cells of undetermined significance and negative follow-up, including at least one tissue biopsy per case, to further investigate the cytologic features of AIS. The AIS smears typically had crowded three-dimensional cellular aggregates, with markedly hyperchromatic nuclei having altered polarity. Frequently, a minor component of AIS formed strips of distinctly columnar cells or sheets. Individual AIS cells occurred in 22 (67%) smears, but these were usually inconspicuous. The AIS smears also had increased nuclear to cytoplasmic ratios (100%), enlarged nuclei (94%), feathering (88%), rosettes (85%), nucleoli (76%), apoptosis (73%), mitoses (64%), multiple nucleoli (18%), and ciliated atypical cells (3%). Cytologic features occurring significantly (P < or = 0.001) more often in AIS cases were a predominance of three-dimensional crowded aggregates (79% vs. 32%), altered nuclear polarity in most groups (88% vs. 16%), marked hyperchromasia (91% vs. 16%), apoptosis (73% vs. 26%), an increased nuclear to cytoplasmic ratio (100% vs. 63%), feathering (88% vs. 26%), and individual atypical cells (67% vs. 16%). In summary, we identified a number of architectural and cellular features that occurred significantly more often in AIS cases than in cases having atypical endocervical cells of undetermined significance and negative follow-up.