Acute kidney injury in a patient with melanuria, diffuse melanosis, and metastatic malignant melanoma.

Diffuse melanosis with melanuria is a rare complication of metastatic malignant melanoma that is associated with a very poor prognosis. Acute kidney injury secondary to melanuria has not been reported previously. We describe a patient with malignant melanoma, diffuse melanosis, and melanuria who developed acute kidney injury that was clinically indicated by an increase in urinary excreted metabolites in the serum. Histopathologic examination of kidney tissue revealed damage to tubules associated with disseminated intra-tubular melanin deposits. Diffuse melanosis with melanuria may lead to morphologic and functional kidney changes and warrants careful monitoring of kidney function in affected malignant melanoma patients.