Generalized Melanosis in Metastatic Malignant Melanoma: The Possible Role of DOPAquinone Metabolites

Abstract

Generalized melanosis occurs very rarely as a complication of malignant melanoma, and the pathogenesis of this condition is still unclear. Histological examination of pigmented skin and measurements of the DOPAquinone metabolites 5-S-cysteinyldopa (5-S-CD) and 6-hydroxy-5-methoxyindole-2-carboxylic acid (6H5MI2C) in the patient’s serum and urine were carried out. Histological examination revealed basal hyperpigmentation, discrete melanoma cells and melanophages around the blood vessels and an unusual melanin deposition within collagen bundles in the dermis. The levels of 5-S-CD and 6H5MI2C were dramatically increased both in the patient’s serum and urine. The deposition of DOPAquinone metabolites secreted by the melanoma cells may contribute to the unusual melanin deposition within collagen bundles in the affected dermis.

Diffuse Melanosis cutis in Disseminated Malignant Melanoma

“…Another finding was giant melanosomes in melanocytes, keratinocytes and melanophages [5,12]. Micrometastases or single metastatic melanoma cells, as rarely have been described [5,13,14], were not found in our patients.…”

Serum Levels of Pigmentation Markers Are Elevated in Patients Undergoing Hemodialysis

“…a non-sun-exposed area, the skin is significantly darker in patients with end-stage renal disease than in healthy controls. Generalized melanosis is also occasionally seen in patients with end-stage malignant melanoma [17,18] . It has been shown that melanoma patients with generalized melanosis excrete trichochromes, a dimeric pheomelanic pigment, in their urine [17] and contain high levels of 5SCD and eumelanin-related metabolites in their sera [18] .…”

Localized Melanosis in an Immunocompromised Patient with Local Metastatic Melanoma

“…To date, 36 cases have been reported in the world literature. The mechanism of pigment deposition has not been elucidated, but several authors have suggested conversion of melanin precursors, 11,12,19,21,26,32,33,35 and a few have observed metastasis of single melanoma cells in the dermis. 1 Typically, generalized melanosis is a late complication of metastatic melanoma and presents as widespread cutaneous and internal organ pigment deposition.…”

“…The first reported case of diffuse melanosis was described by Legg in 1884. 17,22,34,35 Others propose the breakdown of melanoma cells with transfer of melanosomes via the circulation either freely or intracellularly. Murray et al 36 report that the feature that distinguishes melanosis from conventional metastatic melanoma is the accumulation of melanin via the bloodstream throughout the body.…”

“…Murray et al 36 report that the feature that distinguishes melanosis from conventional metastatic melanoma is the accumulation of melanin via the bloodstream throughout the body. 17,22,34,35 This case of melanosis is presented because the melanosis is local rather than diffuse, and abundant melanoma cells are seen within the affected area. They suggest that only continuous access to the circulation by neoplastic melanocytes could explain this.…”