Primary squamous cell carcinoma (SCC) of the prostate is a rare and aggressive malignancy, comprising approximately 0.5% of all prostate cancers. It is frequently diagnosed at an advanced stage, with limited treatment options and poor prognosis. Early diagnosis is challenging due to symptom overlap with benign prostatic conditions and typically normal PSA levels. This study presents a case of metastatic primary prostatic SCC and reviews the current literature surrounding this disease.

A 61-year-old man presented with urinary frequency, poor flow, and occasional urge urinary incontinence, on a background of prior urinary retention and urinary tract infection. His PSA was 0.98ng/ml, DRE revealed benign moderate enlargement, and prostate volume was 67ml. CT abdomen/pelvis showed a low-attenuation lesion in the prostate, a liver lesion, and multiple enlarged pelvic nodes. Pelvic nodal biopsy confirmed moderately differentiated keratinising SCC. TURP was performed for symptom relief. Cystoscopy revealed no bladder or urethral lesions, and skin and lymph node exams were unremarkable. The TURP specimen weighed 66 g, with 80% showing infiltrating moderately differentiated, focally keratinising SCC with necrosis and lymphovascular invasion. Tumour cells stained positively for cytokeratin CAM5.2, cytokeratin 5/6, p63, and p40; weakly for GATA3; focally for cytokeratin 7; and were negative for PSA, PEEP, NKX3.1, TTF-1, and cytokeratin 20. FDG PET-CT confirmed pelvic nodal and hepatic metastases and persistent prostatic avidity. The patient received palliative chemotherapy with carboplatin and paclitaxel and radiotherapy to the prostate and pelvic nodes. He later underwent radiotherapy to metastatic sites for symptom relief and passed away 11 months after diagnosis.

Early diagnosis of prostatic SCC is difficult due to limited distinguishing features and typically normal PSA levels. Many patients present with high-grade disease and distant metastases, with up to 50% having metastatic spread at diagnosis. Urinary obstruction is the most common presenting symptom, occurring in approximately 60% of cases. Treatment depends on disease stage and includes radiotherapy, chemotherapy, and surgery. Hormonal therapy is rarely effective. Cisplatin-based chemotherapy is the most established regimen. Although prostatectomy may be associated with longer survival, this likely reflects earlier stage at presentation. Prognosis remains poor, with five-year survival around 33%, significantly lower than for acinar adenocarcinoma.

Primary prostatic SCC is a rare and aggressive malignancy, often diagnosed at an advanced stage. Limited distinguishing features and normal PSA levels hinder early recognition. Management is guided by disease extent, but data to inform optimal treatment are lacking. Outcomes remain poor, highlighting the need for further research into earlier diagnostic strategies and more effective therapies for this rare disease.