Microglandular endocervical hyperplasia and tubal metaplasia: pitfalls in the diagnosis of adenocarcinoma on cervical smears.

The detection of atypical glandular cells of undetermined significance (AGUS) has risen recently due to the use of new endocervical canal sampling devices, in particular the cytobrush. From April 1993-June 1994, a diagnosis of AGUS ranging from adenocarcinoma in situ (AIS) to invasive adenocarcinoma was initially made on cervical smears from 6 women for whom histologic follow-up data were available. The purpose of this study was to determine if benign cervical glandular lesions can be reliably distinguished from adenocarcinoma on cytology. Review of the smears and histologic slides from 3 patients showed microglandular endocervical hyperplasia on cervical cone specimens. Cervical smears from 2 of these patients showed clusters of small-to-medium-sized cells with nuclei containing coarse, granular chromatin and prominent nucleoli. Cytoplasmic vacuoles and engulfment of neutrophils were present, findings suggestive of endometrial adenocarcinoma. The third patient's smear showed clusters of large cells with ample, vacuolated cytoplasm and vesicular nuclei containing prominent nucleoli, findings suggestive of endocervical adenocarcinoma. In 3 cases evaluated by cervical conization, histologic slides showed tubal metaplasia. The cervical smears showed clusters and sheets of cells with round-to-oval-shaped nuclei containing evenly distributed, finely granular chromatin and inconspicuous nucleoli. Pseudoglandular formation was present in 2 cases, a finding suggestive of AIS. Since the cytologic features of microglandular endocervical hyperplasia and tubal metaplasia overlap those of adenocarcinoma, a differential diagnosis is prudent on cytologic smears of AGUS.