Diffuse melanosis cutis related to dermal micrometastases as the first clinical symptom of distant metastatic malignant melanoma

Abstract

Rationale:Diffuse melanosis cutis (DMC) is a very rare sign of malignant melanoma progression. The condition usually develops after approximately one year from melanoma diagnosis in a patient with metastatic tumors and after anticancer treatment with cytostatic medications.Patient concerns:A 72-year old Caucasian man was admitted to the Department of Dermatology with DMC for 4 months and the history of two melanomas treated surgically 30 years and 9 months before present hospitalization.Diagnosis:Histological and immunohistochemical examinations of DMC biopsy indicated melanoma metastatic cells as well as free deposits of melanin and melanophage presence in the dermis.Interventions:The patient refused to the treatment.Outcomes:The patient died eight months after DMC appeared.Lessons:DMC is a rare presentation of advanced MM and is a bad prognostic factor. The pathomechanisms of the discoloration of the skin are not fully explained. The role of micrometastases, as well as melanin precursors, released during lysis of MM metastases, and growth factors may play a role in the development of the symptom.

Diffuse melanosis cutis secondary to metastatic malignant melanoma: case report

“…Until 2017, more than 70 cases of DMC were reported, however, mechanisms of the condition have not been elucidated [2]. So far, Different pathogenic mechanisms leading to diffuse melanosis have been discussed.…”

“…Other several lines of evidence suggest that the direct cause of the skin darkening is melanin derived from the melanoma micrometastases in the dermis [2].…”

“…This may occur as a result of rapid turnover of neoplastic deposits, ischemia, immunological responses, or oncologic therapies [1]. Circulating precursors would have the capacity to traverse the glomerulus and be excreted in the urine, causing melanuria [1][2][3][4][5][6].…”

“…It attests a generally advanced metastatic tumor extension. The discoloration represents the abnormal presence of pigment within the dermis causing scattering of light [1], and is usually more intensive on sun-exposed areas, including head and upper torso [2]. Usually, dark urine associated with melanüri, darkening of the serum and peritoneal fluid can be also seen [3].…”

“…In the literature, approximately 72 cases of DMC have been described until now, most of them being associated with multiple organ metastases [2].…”