Metachronous Penile Metastasis From Advanced Anorectal Carcinoma: A Case Report

Secondary penile involvement in anorectal carcinoma represents an uncommon manifestation of advanced metastatic disease, with few cases documented in the literature. Despite the rich vascular and lymphatic supply of penile tissue, penile metastases arise predominantly from genitourinary primaries; an anorectal origin is exceptionally rare and is generally associated with poor oncologic outcomes. We report the case of a middle-aged man with T4N2M1 anorectal squamous cell carcinoma (SCC) and synchronous hepatic metastases who developed a painful ulcerative lesion and a firm subcutaneous nodule along the lateral penile shaft during concurrent chemoradiotherapy. Doppler ultrasonography identified a 1.4 × 1.4 cm hyperechoic, hypervascular lesion. Pelvic magnetic resonance imaging demonstrated multiple hypoenhancing lesions involving the corpora cavernosa, corpus spongiosum, and penile crura. Histopathological examination confirmed metastatic SCC with immunophenotypic concordance with the anorectal primary tumor. A multidisciplinary board recommended radical penectomy with perineal urinary diversion; however, due to rapid systemic disease progression and declining performance status, the patient transitioned to best supportive care. Penile metastasis from anorectal carcinoma typically presents as a metachronous event and is indicative of widespread systemic dissemination with a guarded prognosis. Diagnosis is established through histopathological confirmation, supported by cross-sectional imaging to define the anatomical extent of disease. Treatment is primarily palliative and requires individualized multidisciplinary assessment that integrates disease burden, functional status, and patient-centered goals of care. Awareness of this rare metastatic pattern among clinicians managing pelvic malignancies is essential to facilitate prompt diagnostic evaluation and appropriate goals-of-care discussions.