Cytologic detection of malignant melanoma in urine. A case report.

This case illustrates the diagnosis of malignant melanoma from a sample of urine by cytologic examination without prior knowledge of cutaneous malignant melanoma and in the absence of chemical melanuria. The exfoliated cells were large, oval and solitary. They contained large, vesicular, sharply defined, often regularly contoured, eccentric nuclei with red macronucleoli. Their cytoplasm was cyanophilic with granular, brown-black pigment that histochemically was melanin. These composite characteristics, distinctive for malignant melanoma, eliminated other diagnostic possibilities. Surgical management was guided by an accurate cytologic diagnosis. The report emphasizes the clinical usefulness and criteria for accurate cytologic detection of metastatic malignant melanoma in urine.