Diffuse Melanosis Cutis as the First Sign of Recurrence of Low-Risk Melanoma: Case Report and Systematic Review

Introduction: Diffuse Melanosis Cutis (DMC) is a rare and late complication of metastatic malignant melanoma (MM) characterized by progressive pigmentation of skin and sometimes mucous membranes. The distinctive feature is the widespread and progressive deposition of melanin precursors in the dermis. Objectives: The purpose of this review is to define the clinical and demographic features of DMC and to promote a deeper insight into the clinical manifestation, histological findings, and pathophysiology behind DMC. Methods: We have conducted a systematic review of the literature on published DMC in compliance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis. We also reported a case of DMC secondary to low-risk melanoma. Results: Overall, including our case report, we reported 53 articles described 62 DMC patients. Breslow level of primary melanoma was reported having a mean value of 3.3 mm. The mean survival rate from onset of DMC resulted being 4.36 months. Conclusions: Among the most widely accepted etiopathogenetic hypotheses are deposition of melanic precursors in the dermis following tumor lysis, melanocyte proliferation induced by neoplastic growth factors, and the presence of diffuse dermal micro-metastases of MM. However, unanimous consensus on the proposed etiopathogenetic models of DMC is still lacking.