Atypical squamous cells in the urine revealing endometrioid adenocarcinoma of the endometrium with squamous cell differentiation: a case report.

Urine cytology is mainly used to detect urothelial carcinoma (UC), especially for high-grade lesions including urothelial carcinoma in situ. Benign squamous cells are often seen in the urine specimens of women, they are either exfoliated from the trigone area of the bladder, the urethra, or the cervicovaginal region. However, abnormal squamous cells in the urine raise concerns of abnormalities of the urinary tract and cervicovaginal area which range from squamous metaplasia of the urothelium, a cervicovaginal squamous intraepithelial lesion, condyloma acuminatum of the bladder, UC with squamous differentiation, and squamous cell carcinoma. We present here a unique case of atypical squamous cells (ASCs) in the urine subsequently leading to the diagnosis of endometrioid adenocarcinoma of the endometrium with squamous differentiation. The presence of ASCs in voided urine is a rare finding that may indicate an underlying malignancy. Careful evaluation of squamous cells in the urine is an important part of our daily cytopathology practice.