Primary amelanotic melanoma of the male urethra: A rare entity and diagnostic challenge

摘要

Malignant melanoma (melanoma) is a tumor of melanocytes that usually presents as cutaneous lesions. While melanoma can infrequently appear as a primary tumor elsewhere in the body, it is extremely rare in the urethra and even rarer as amelanotic malignant melanoma. We report the case of a 66-year-old male who presented with painless gross hematuria and lower urinary tract obstructive symptoms in the recent 2 weeks prior to his visit to our clinic. History and physical examination, including external genital examination, abdominopelvic sonography, and urine culture, were not conclusive. Cystourethroscopy revealed a creamy pink fragile mass located in the anterior proximal urethra that extended to the mid portion. Pathological examination of this lesion confirmed the diagnosis of amelanotic malignant melanoma using immunohistochemistry. Radical cystourethrectomy with ileal conduit was subsequently conducted. Although this tumor is extremely rare, urologists and pathologists should consider malignant melanoma as a diagnosis in patients with urethral tumor because of the likelihood of early metastasis and, consequently, poor prognosis. Complete surgical removal of the tumor and use of effective therapies can improve outcomes in these patients.