Cellular pseudosarcomatous fibroepithelial stromal polyps of the lower female genital tract: an underrecognized lesion often misdiagnosed as sarcoma.

Fibroepithelial stromal polyps of the vulvovaginal region are benign lesions that, when bland or hypocellular, are readily recognized. However those that exhibit bizarre cytomorphology, atypical mitoses, or hypercellularity, raising the possibility of malignancy, continue to be underrecognized. The authors reviewed a series of fibroepithelial stromal polyps to characterize further the morphologic features that can lead to a misdiagnosis of sarcoma. A total of 33 of 65 consecutive cases of fibroepithelial stromal polyps retrieved from the authors' consultation files were remarkable for marked hypercellularity (33 of 33), marked cytologic pleomorphism (21 of 33), mitotic counts of more than 10 mitoses per 10 high-power fields (12 of 33), and the presence of atypical mitoses (14 of 33). A total of 16 of 33 lesions had three or more of these features. Important morphologic clues to the diagnosis (shared with usual polyps at this site) were lack of an identifiable lesional margin, extension of abnormal stromal tissue up to the mucosal-submucosal interface, and the frequent presence of individually scattered multinucleate stromal cells, most often located close to the surface epithelium. Immunohistochemically, seven of 12 cases were desmin positive and one of 11 cases were smooth muscle actin positive. The age range of patients was 16 to 75 years (median, 32 years), and 21 patients (64%) were premenopausal. Sites included the vagina (18 of 33), cervix (seven of 33), and vulva (eight of 33). A total of 14 of 33 patients were pregnant, three patients were taking Tamoxifen, and one patient was on oral progesterone. Eight of 33 patients had multiple lesions at the time of presentation, of whom five were pregnant. Clinical follow-up was available in 21 of 33 patients. Three of 21 patients with follow-up had local, nondestructive recurrence. Two of these patients had multiple recurrences. None of the patients followed developed metastases. Cytologic atypia has been a previously recognized feature in these lesions; however, the occurrence of marked stromal cellularity and a mitotic rate of more than 10 mitoses per 10 high-power fields have not been emphasized previously. Moreover, the combination of these features has only rarely been documented. Awareness of the spectrum of histologic features that these lesions can exhibit is crucial in their accurate recognition, thus avoiding potential overtreatment.