The significance of benign endometrial cells in cervicovaginal smears

The success of the routine Papanicolaou (pap) smear in reducing the incidence and mortality of cervical cancer has been chronicled extensively. Unfortunately, endometrial cancer, the most common malignancy of the gynecologic tract, continues to lack a screening modality of comparable efficacy. It is generally accepted that the Papanicolau test has a low sensitivity for detecting endometrial disease. Nonetheless, it remains true that endometrial cells are not uncommonly identified on routine cervicovaginal smears and along with each case comes an associated responsibility for pathologists to assess cytologic features, assign a potential clinical significance, and make a decision on reporting this finding. When endometrial cells with an entirely normal cytologic appearance are identified on an otherwise unremarkable cervicovaginal smear, the central question raised is whether such cells are exfoliating physiologically or whether their exfoliation is pathologic in response to an underlying endometrial disease. Additionally, in the former scenario, could subsets of patients be defined in which the reporting of this finding is deemed unnecessary in the cytologic report? In this contribution, we explore the clinical significance of finding normal endometrial cells in cervicovaginal smears based on a review of the medical literature of the last half-century. The historical and evidentiary basis for the Bethesda 2001 recommendations, which calls for the reporting of cytologically benign endometrial cells only in patients 40 years and older, is reviewed in detail.