Atypical Presentation of Congenital Dermal Melanocytosis (Mongolian Spot) and Its Medico-Legal Significance

Abstract

Introduction: The paper discusses the clinical and forensic significance of Congenital Dermal Melanocytosis (CDM), also known as the "Mongolian spot." CDM is a benign pigmented condition that, in cases of atypical localization, may be misidentified as traumatic injury (hematoma) or postmortem putrefactive changes. The study aims to analyze the prevalence of this condition and emphasize the importance of differential diagnosis in atypical cases. Methodology: The study is based on a retrospective analysis of 129 forensic cases accumulated between 2013 and 2025. An exclusion method was applied (bodies with distinct putrefactive changes and cases of antenatal death were removed). For the verification of atypical cases, histomorphological examination was conducted using Perls' and Masson-Fontana specific reactions. Results: The prevalence of CDM in the selected population was 5.4%. A sharp ethnic differentiation was revealed: the prevalence in the Chinese group was 62.5%, while in the Georgian group, it was 1.68%. Typical localization (sacrococcygeal) was characterized in 71.4% of cases, while atypical positioning was recorded in 28.6%. The case of a 1-year-and-11-month-old Chinese child is described in detail, where a histological examination of a spot in the abdominal area confirmed the presence of melanin and excluded hemorrhagic genesis. Conclusion: The atypical localization of CDM poses a significant forensic challenge and requires consideration of ethnic anamnesis. To prevent misleading forensic experts, the accurate recording of pigmented spots at birth in primary medical documentation is critically important. In suspicious cases, histochemical examination remains the "gold standard" for differential diagnosis.