Glans penis yet another place where malignant melanoma can appear

Abstract

Introduction. Primary melanomas of the glans penis and male urethra are exceptionally rare, constituting less than 0.1% of all malignant melanomas, and 1.4% of all penile cancers. Melanomas arise from malignant transformation of melanocytes. Melanomas situated on the penis may be cutaneous or mucosal. The primary cause of cutaneous melanoma is ultraviolet light exposure, but the sunlight is not a causative factor for mucosal melanomas, and their etiology is unknown. Case report. A 66-year-old uncircumcised men presented with blackish tumorous nodule on glans penis with a size of 13x10 mm on peduncle 2x2 mm. Biopsy with wedge excision was made in favor of malignant melanoma. Chest X-ray and abdominal CT were made and metastasis in the left superficial inguinal lymph nodes with a size of 16x12x11 mm was detected. A partial penectomy with 20 mm resection margins and left inguinal lymphadenectomy was performed. Only one positive node was recorded. No residual tumorous tissue was detected on the penis. Histopathologic classification including the first finding was Breslow’s 4 (5 mm), Clark’s 3, pT4b, pN1b, Stage IIIC. The patient was referred to oncology where he received chemotherapy. There are no signs of recurrence and metastases in other locations two years following the surgery. Discussion: Melanoma on glans penis typically presents as colored lesions, the color varying from black, blue, brown, grey or amelanotic. Median patient age is 65 years. Once the diagnosis is verified, serum LDH levels are determined and CT scan of brain, chest, abdomen, and pelvis or positron emission tomography scans are performed to assess the disease’s stage. For stage I/stage A organ-sparing surgery with local excision, urethrectomy, glans amputation or partial penectomy is sufficient. The benefit of lymphadenectomy remains questionable. However, for patient with groin lymph node metastases an ilioinguinal lymph node dissection should be undertaken. For stage II/stage B glans and urethral melanomas, the prognosis is poor. In patients with lymph node involvement, the reported two-year survival rate is nearly 0%. Instead of radical surgery, tumor excision combined with chemo-immunotherapy can be used with equal results and lesser postoperative morbidity. Radiotherapy has shown no special benefit in glans and urethral melanomas. Mucosal malignant melanomas have worse prognosis than the cutaneous form. Two and five years overall survival in a patient with penis melanoma is 63% and 31%, respectively. Adverse prognostic factors are tumor thickness >3.5 mm, ulceration, and tumor diameter >15 mm. Conclusion. Malignant melanoma can appear on any part of the skin, and even on the glans penis. The appearance of a tumor formation with blackish discoloration should always alert us to the possibility of malignant melanoma. Although these cancers are very rare in the literature they have high mortality. Treatment is surgical and includes conservative procedures for localized disease and radical surgeries for locally advanced cases.