Complex papillary hyperplasia of the endometrium: an uncommon case report with cytopathological features and diagnostic implications.

Papillary proliferations of the endometrium, without atypia have been uncommonly documented, including on cytology specimens. Herein, we present an uncommon case of a 55-year-old obese lady, on antihypertensive medications, who presented with history of irregular perimenopausal bleeding. A year ago, she was diagnosed with simple cystic hyperplasia on dilation and curettage specimen. Presently, she underwent endometrial aspiration. Cytology smears were prepared from the collected tissue specimen that was further submitted for histopathological analysis. Although the smears were initially diagnosed as negative for malignancy, the tissue sections were reported as a uterine papillary serous carcinoma (UPSC). Review of the smears revealed prominent overlapping clusters and papillary arrangements of relatively banal endometrial cells exhibiting focal metaplasia. Histopathology sections confirmed diagnosis of complex papillary hyperplasia (CPH). Immunohistochemical (IHC) stains reinforced this impression with diffuse estrogen receptor positivity, low Ki-67/MIB1, and lack of diffuse p53 immunostaining. Subsequent hysterectomy, at the time of intraoperative consultation showed a small residual focus of CPH, restricted to endometrium with intramural leiomyomas and adenomyosis. This case is presented to highlight the fact that despite lack of significant atypia, cytological features like overlapping, clustering, and papillary formations are indicators of papillary lesions of the endometrium, including CPH, especially in postmenopausal women. On histopathology, in spite of conspicuous papillary formations, lack of significant nuclear pleomorphism, and tumor invasion are helpful features in avoiding an overdiagnosis of UPSC in such cases. IHC stains are supportive. Correct identification has significant therapeutic implications.