Metastatic Melanoma and Melanogenuria

We report a case of a 70-year-old Hawaiian man with an exophytic black nodule on the left suprascapular region of several years’ duration. Histopathologic examination of the excised lesion showed a nodular melanoma with 17-mm Breslow thickness. The patient had firm fixed lymph nodes circumferentially around his neck. He underwent palliative cervical lymph node dissection to remove the compressive nodes but declined further therapy. One year later, the patient’s skin was noted to have a generalized uniformly gray-brown color. Physical examination showed ulcerated masses on his trunk, right arm, and both axillae. A urine specimen initially was dark yellow but turned black after exposure to air at room temperature and ambient light for several minutes.

Black urine, termed melanuria, is a rare finding in patients with disseminated melanoma. In melanogenuria, the urine is yellow and darkens as the colorless melanin precursors oxidize in the presence of air. Detection of these urinary melanin precursors may someday help determine the prognosis of melanoma and monitor response to treatment.