BackgroundGiant congenital melanocytic nevus is a very rare condition characterized by a large skin lesion and an increased risk of complications like neurocutaneous melanosis and malignant transformation. Reports of giant congenital melanocytic nevus are scarce in the sub-Saharan African literature and here we present a case of this disease in a Cameroonian adolescent.Case presentationA 12-year-old Cameroonian girl from the "Baka" ethnic group, with no relevant family and medical histories presented with a progressively extensive brownish-black nodular hypertrophic skin lesion of approximately 45 cm, which she had had since she was 2-days old. The lesion covered her entire back giving an appearance of “turtle child”, which was highly suggestive of a giant congenital melanocytic nevus. She was booked in for a surgical intervention organized by a health campaign within her community. Meanwhile she was provided with psychological support and her family was counseled on warning signs of complications which would warrant an urgent consultation.ConclusionsHere we presented a case of giant congenital melanocytic nevus, apparently the first in the Cameroonian literature. In view of the potential severe complications as well as psychological trauma of this pathology, we draw clinicians’ attention to this extremely rare but real pathology in our country, for a timely diagnosis and management.