Malignant Priapism as the Sole Initial Manifestation of Metastatic Carcinoma with Suspected Pulmonary Origin: A Case Report and Review of the Literature.

Background and Clinical Significance: Malignant priapism is a rare manifestation of advanced malignancy caused by malignant infiltration of the corpora cavernosa. We report a case of persistent and refractory priapism associated with penile carcinoma and extensive metastatic disease, with a suspected pulmonary primary. Case Presentation: An 81-year-old man with a history of prostate cancer treated by radical prostatectomy and persistently undetectable PSA levels developed persistent low-flow priapism. Despite aspiration and irrigation, followed by distal and proximal shunting procedures, the condition recurred with progressive corporal induration and severe pain. Cavernous biopsy was initially interpreted as moderately differentiated squamous carcinoma, while total penectomy performed for refractory pain showed poorly differentiated carcinoma with morphological adenosquamous features. CT and PET/CT demonstrated a pulmonary mass and widespread metastatic disease, although bronchoscopy was non-diagnostic and no histological confirmation of the pulmonary lesion was obtained. A focused review of the literature identified 32 published cases of malignant priapism; bladder cancer was the most frequently reported primary malignancy (37.5%), followed by prostate cancer (18.8%) and renal cell carcinoma (9.4%), while penectomy was performed in 34.4% of cases. Conclusions: Persistent or recurrent priapism associated with corporal induration, progressive or atypical pain, failure of conventional treatment, or discordant imaging findings should raise suspicion of malignant infiltration and prompt consideration of repeat imaging and tissue sampling. In the present case, carcinoma involving the penile structures was histologically confirmed, whereas pulmonary origin remained a clinicoradiological suspicion; penectomy provided immediate pain relief in the setting of extensive refractory local disease.