ASN's Mission

To create a world without kidney diseases, the ASN Alliance for Kidney Health elevates care by educating and informing, driving breakthroughs and innovation, and advocating for policies that create transformative changes in kidney medicine throughout the world.

learn more

Contact ASN

1401 H St, NW, Ste 900, Washington, DC 20005


The Latest on X

Kidney Week

Please note that you are viewing an archived section from 2023 and some content may be unavailable. To unlock all content for 2023, please visit the archives.

Abstract: SA-PO1028

Melanuria: Black Urine as a Presenting Sign of Metastatic Melanoma

Session Information

Category: Pathology and Lab Medicine

  • 1800 Pathology and Lab Medicine


  • Nogueira De Sa, Patricia, University of Pennsylvania, Philadelphia, Pennsylvania, United States
  • Zariat, Asheen, University of Pennsylvania, Philadelphia, Pennsylvania, United States
  • Shulman, Rachel, University of Pennsylvania, Philadelphia, Pennsylvania, United States
  • Leonberg-Yoo, Amanda K., University of Pennsylvania, Philadelphia, Pennsylvania, United States

The worldwide incidence of malignant melanoma has been increasing at an average annual rate of 5%.1We describe a case of melanuria as an initial sign of metastatic melanoma in a previously healthy young woman.

Case Description

A 24-year-old female with no medical history presented with two weeks of abdominal pain.On admission, she had mild tachycardia. Physical exam was notable for abdominal tenderness and lower extremity edema.Blood work showed creatinine of 1.5 mg/dL,lactate 19mmol/L,LDH 5000 IU/L.Amber urine that turned black upon exposure to air.Urine studies were negative for hemoglobin and bilirubin and microscopy showed dark brown casts and atypical cells with dense inclusions exhibiting a dark rim.Abdominal CT showed multiple hepatic and splenic lesions,suspicious for neoplasm.Liver biopsy showed BRAF-negative metastatic melanoma.Despite treatment,the patient expired on hospital day 13th.


Melanuria is the urinary excretion of melanin precursors leading to black discoloration of the urine.It is present in up to 15% of cases of malignant melanoma and typically occurs with diffuse melanosis.2,3Urine sediment may show atypical pigment-laden cells and dark brown casts.Our patient had dark casts with atypical cells suggesting melanin-containing tubular epithelial cells and histiocytes.Although we did not test her urine for melanin precursors,we proposed the melanuria resulted from extensive tumor necrosis causing cytolysis of melanocytes and subsequent excretion in the urine.This case demonstrates that metastatic melanoma should be considered in the differential diagnosis of black urine.