Endometriosis mimicking glandular atypia in a cervical cytology

A 41-year-old patient, G3P0A0, with previous history of two obstetric curettages due to retained abortions and previous negative Pap smears, attended to her routine annual Pap smear screening. The cervical cytology revealed tridimensional hyperchromatic glandular groups with nuclear overlapping [ Figure 1a ], round nuclei in the center, and palisading nuclei on the periphery of the cluster with occasional mitosis [Figure 1b and c ]; no feathering was seen. The atypical glandular cells were considered to be endocervical in origin, and were interpreted as atypical glandular cells, not otherwise specified (NOS). (a) Tridimensional hyperchromatic groups (H&E, ×200), (b) Glandular group shows round overlapping nuclei with occasional mitosis and palisading nuclei at the periphery (H&E, ×400). (c) Atypical glandular cells with hyperchromatic palisading nuclei (H&E, ×400). (d) Cervical biopsy with central foci of ectopic endometrial glands surrounded by endometrial stroma and lined in the periphery by unremarkable endocervical glands (H&E, ×100). Immunohistochemistry, shows (e) reactive endometrial glands and negative endocervical glands with vimentin (Vimentin, ×100) and (f) reactive endometrial stroma with CD10 (CD10, ×100) Patient was subjected to colposcopy that was negative, following which she was taken for endocervical biopsy. The sample was fixed in buffered formalin 10%, and slides were stained with hematoxylin and eosin. Tissue sections revealed foci of ectopic endometrioid glands surrounded by endometrial stroma [ Figure 1d ] admixed with benign endocervical glands. Immunohistochemistry was reactive for vimentin on endometrioid glands [ Figure 1e ] and for CD10 in endometrial stoma [ Figure 1f ], but was negative in endocervical glands. Findings were consistent with cervical endometriosis.

Endometriosis is defined as the presence of endometrial glands and stroma in ectopic localizations outer than the uterine cavity. The most frequent site of implantation is the ovaries and pelvic cavity, followed by the bowel, bladder, umbilical region, skin, and perianal region.[ 1 ] Endometriosis of the uterine cervix is uncommon and may have different morphologies, such as superficial, deep, and polypoid.[ 2 3 ] Superficial endometriosis can be detected in cervicovaginal cytology and lead to errors in interpretation as atypical glandular cells.[ 4 5 ] We report the case of a patient with superficial endometriosis, detected incidentally on a routine cervical cytology interpreted as atypical glandular cells, and correlation with histopathology.

Since 2001 when the Bethesda system was incorporated into the classification of glandular abnormalities, the need to classify endocervical or endometrial samples was investigated by multiple studies that reported the difficulty in the interpretation of these lesions and the high interobserver variability.[ 6 7 ] Incidence of cervical endometriosis has been reported to be between 0.7 and 2.4% of colposcopies.[ 8 ] The morphology may range from shallow-to-deep and polypoid cells that can be detected in Pap smear and can lead to an interpretation of atypical glandular cells, mimicking endocervical neoplasia, as the morphology of endometrial cells may present a wide morphologic spectrum, making the histopathological examination definitive in defining the final diagnosis. Similar to previous reports, the most common finding, as in the presented case, was the three-dimensional clusters of glandular cells and cytologic atypia with slight increase in nuclear size and occasional mitosis.[ 1 ] The differential diagnosis of atypical glandular cells apart from endometriosis includes benign conditions such as tubal metaplasia and lower uterine segment sampling and malignant conditions as adenocarcinoma in situ of the endocervix, and endometrial adenocarcinoma.[ 1 9 ] To the best of our knowledge, there are only 48 cases reported of endometriosis initially observed in the cytology with definitive diagnosis in the biopsy. The history of previous gynecological procedures together with atypical groups lining the normal endocervix in the absence of apoptosis, mitosis, and feathering of the cytoplasm are useful to suspect that the findings are mimicking malignancy. Nil. There are no conflicts of interest.