Atypical glandular cells of undetermined significance (AGUS): clinical considerations and cytohistologic correlation

The diagnoses of atypical glandular cells of undetermined significance (AGUS) made upon evaluation of cervical/vaginal (Pap) smears is examined to ascertain salient clinical and cytologic features that may lead to better characterization of the true nature of these lesions. Prior history of squamous dysplasia, age of the patient, and the occurrence of abnormal microbiopsy tissue fragments are investigated to determine their value in the proper evaluation of AGUS specimens. Of the 86,234 Pap smears submitted to our laboratory during a period of 2 yr, 187 (0.2%) were diagnosed as AGUS. Available follow-up in 128 (69%) cases revealed 54 (42%) significant tissue proven abnormalities, the majority (55%, 30 patients) of which were diagnosed as squamous intraepithelial lesions (SIL). Squamous dysplasia is significantly more common in women younger than 40 (15/18, 83%) and in patients with prior history of SIL (29/30, 97%). In addition, all nine patients diagnosed with endometrial lesions on subsequent histology were older than 40. Age, however, was not a discriminating factor in women proven to have endocervical glandular lesions. Additionally, certain tissue fragment cytomorphologic features were significantly more often observed on follow-up in specific histologic diagnostic categories. The Pap smears of patients diagnosed with SIL were noted to contain tissue fragments composed of both dysplastic squamous and benign glandular cells in 29 of 30 (97%). The presence of two distinct populations of glandular tissue fragments (typical and atypical) was found in the Pap smears of all nine women with endometrial abnormalities and in the smears of most women subsequently diagnosed with endocervical glandular lesions (87%, 13/15). These observations suggest that a more specific and clinically useful Pap smear interpretation other than AGUS is often possible by consideration of the patient's age and prior history along with the correct identification of the type of atypical cells observed in abnormal tissue fragments.