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

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.