Bladder Washing Cytology in the Detection of High-Grade Prostatic Adenocarcinoma: A Case Report

Bladder washing cytology is a valuable diagnostic tool primarily used in the evaluation of urothelial malignancies. However, its role in detecting metastatic or secondary malignancies, such as high-grade prostatic adenocarcinoma, is less commonly recognized. We present the case of an 82-year-old man whose post-cystoscopy bladder washing cytology revealed atypical glandular cells. Immunocytochemical staining showed strong NKX3.1 nuclear positivity, suggesting a prostatic origin. Subsequent transurethral resection of the prostate confirmed high-grade prostatic adenocarcinoma with intraductal carcinoma and a cribriform growth pattern, classified as International Society of Urological Pathology (ISUP) Grade Group 4 (Gleason score 4+4=8). Notably, NKX3.1-positive malignant cells were also identified in a follow-up voided urine sample. This case underscores the potential utility of urine cytology, particularly when supplemented by immunocytochemistry, in the diagnosis of prostate cancer.