Melanoma of the urogenital tract is extremely rare, accounting for less than 0.1% of melanoma cases. The global literature currently describes only 220 cases of penile melanoma, most commonly located on the glans penis.
Results: Penile melanoma accounts for 0.7% of penile cancers and 0.18% of melanoma cases. The average patient age for the six cases we reviewed was 44.5 years. Three of these cases (50%) involved ulceration, one case (16.7%) involved lymphovascular invasion, and three cases (50%) involved mitosis ≥ 1 mm2 (0.38–4.7 mm). The average depth of invasion (Breslow) in the five cases that reported this measure was 2.1 mm (0.38–4.7 mm). Applying the American Joint Committee on Cancer tumour, node, metastases (AJCC TNM) staging system, one case was Tx (16.7%), two cases were T1 (33.3%), one case was T2 (16.7%), one case was T3 (16.7%), and one case was T4 (16.7%). Five cases (83.3%) involved wide local resection, and only one case involved partial penile amputation. Four cases (66.7%) involved primary bilateral inguinocrural lymphadenectomy, and only one of those four cases involved lymphatic metastatic disease. One case (16.7%) involved lymphatic recurrence at 12 months in a patient who survived 38 months. One case (16.7%) involved local recurrence at 13 months in a patient who has survived 53 months. Eighty per cent of these patients remain alive, with no evidence of disease after an average follow-up of 96.7 months.
Conclusion: Penile melanoma prognosis depends on the initial clinical stage of the disease. The risk of lymphatic involvement seems to be related to the same risk factors used to assess cutaneous melanoma. Clinicians can thus assess penile melanoma using the AJCC staging system. The use of sentinel lymph node biopsy to determine staging is also becoming more common and could replace prophylactic bilateral inguinal dissection.