Adenocarcinoma in situ in cervical smears with a small cell (endometrioid) pattern: distinction from cells directly sampled from the upper endocervical canal or lower segment of the endometrium.

Abstract

Adenocarcinoma in situ (AIS) with small, endometrioid cells in cervicovaginal smears, is a source of false-negative diagnoses because of the difficulty in distinguishing these cells from endometrial cells of the lower uterine segment or benign cells from the upper endocervical canal. This study was designed to elucidate the most useful criteria for this distinction. Three observers blinded to the actual diagnoses reviewed 29 preselected cases (AIS, 17; benign, 12) that had originally caused diagnostic difficulty. Each observer made a diagnosis and evaluated 15 preselected diagnostic criteria. All 3 observers agreed on the correct diagnosis in 19 (66%) of 29 cases, and at least 2 observers agreed on the correct diagnosis in 27 (93%) of 29 cases. No case was misdiagnosed by all 3 observers. The most useful criteria for the diagnosis of AIS are a predominance of groups with marked crowding, focal feathering, nuclear hyperchromatism with coarsening of chromatin, and occasional mitotic figures. Sheets of cells, endometrial tubules, and endometrial stroma favor a benign diagnosis. Although 12 (14%) of 87 possible diagnoses were erroneous, well-preserved, small, endometrioid AIS cells can be identified correctly on cervical smears and distinguished from epithelium from the lower uterine segment and high endocervical canal in most cases using the aforementioned criteria.