Primary mucinous adenocarcinoma of the urethra: a diagnostic conundrum – two case reports and literature review

Primary mucinous adenocarcinoma (PMAC) of the urethra is an exceptionally rare subtype of primary urethral carcinoma, with limited published data to guide diagnosis or treatment. Most literature consists of isolated case reports, and the non-specific presentation often delays diagnosis. This report presents two further cases and a review of the literature with a view to expand current understanding. We report two cases of PMAC. The first involves a 67-year-old male with progressive lower urinary tract symptoms initially treated as benign prostatic hyperplasia. Histology following a transurethral resection of the prostate revealed invasive mucinous adenocarcinoma with enteric features. He underwent radical prostatectomy, chemotherapy and radiotherapy for metastatic disease. The second case is a 52-year-old female with chronic urinary symptoms and a urethral mass initially misattributed to being from gynaecological origin. However, a biopsy later confirmed mucinous adenocarcinoma of the urethra. She underwent chemotherapy and radiotherapy, with partial response, but later developed further metastatic spread and is now undergoing palliative chemotherapy. PMAC is aggressive, often presents with non-specific urinary symptoms and lacks standardised diagnostic or treatment protocols. These cases highlight the importance of early detection through biopsies, immunohistochemical analysis and a multidisciplinary approach. Broader awareness and further reporting of cases are essential to develop evidence-based diagnostic and treatment guidelines for this rare malignancy.