Rare Penile Shaft Metastasis in Carcinoma Prostate at Initial Presentation: Documentation on 68Ga-PSMA-11 PET/CT and Its Clinical Implications

Abstract Penile metastasis of carcinoma prostate is a rare occurrence and often a marker of advanced systemic disease with poor prognosis. We present two patients with carcinoma prostate who demonstrated penile metastasis on gallium-68 (68Ga)-prostate-specific membrane antigen-11 (PSMA-11) positron emission tomography/computed tomography (PET/CT) on initial staging. The first patient, an 84-year-old man, presenting with increased frequency of urination, and biopsy-proven adenocarcinoma prostate, had serum prostate-specific antigen (PSA) of > 100 ng/mL. 68Ga-PSMA-11 PET/CT showed PSMA-avid primary prostatic lesion with extensive nodal and skeletal metastatic disease along with focal penile shaft lesion. The other patient, a 78-year-old man presented with hematuria and urinary retention, with subsequent biopsy diagnosis of prostatic adenocarcinoma with serum PSA level > 100 ng/mL. 68Ga-PSMA-11 PET/CT showed primary prostatic lesion with pelvic nodal and skeletal metastases with focal penile shaft tracer uptake. In both patients, 68Ga-PSMA-11 PET/CT detected rare penile metastatic site of carcinoma prostate, reported to indicate poor prognosis and thus, helped in risk stratification and management. It is important to study the pathophysiology and biological behavior of such disease so as to precisely prognosticate and manage the patients.