Pathogenesis of generalized melanosis with melanuria and melanoptysis secondary to malignant melanoma

A case of disseminated malignant melanoma with generalized melanosis of the skin and other tissues, melanuria, melanoptysis, and a dark brown blood serum is reported. The reticuloendothelial system contained large amounts of melanin pigment. Lysis of degenerating pigment‐loaded melanoma cells in peripheral blood vessels seemed to be of considerable importance in the pigmentation of tissues. Focal pigmentation of capillary endothelium and perivascular deposition of melanin pigment in macrophages and, occasionally, in other cells, was noted. Single cell metastases contributed to melanin pigmentation of most organs, but were not found in sections of the skin. Melanoptysis (black sputum) was due to diffuse melanoma cell infiltration of the lungs, with secondary pigment deposition in macrophages and in bronchial epithelial cells. In this case the ‘glomerular melanoma cell emboli’ recorded by previous authors consisted of melanin pigment and cell debris. Focal damage of glomeruli affected by pigment emboli is described allowing access of melanoma cell debris (including melanin pigment granules) into glomerular tubules.