Congenital giant pigmented nevi: Clinical features and risk of malignancy

Abstract

There is general agreement that congenital giant pigmented nevi (CGPN) are precursors to malignant melanoma; however, the magnitude of the risk of malignant transformation is the subject of wide controversy. The goal of this study was to present the authors' experience with CGPN and more specifically their experience with the risk of malignancy. To identify the general features of CGPN a detailed retrospective chart review was performed at The Hospital for Sick Children in Toronto (1979 to 1994, n=84). There were 39 boys and 45 girls. The average size at presentation was 5.24% of the body surface area, and 36.9% of the nevus were located on the head and neck. An important finding was the high percentage of associated extra cutaneous disorders in patients with CGPN (23%) including a case of leptomeningeal melanocytosis. Tissue expansion was the most commonly used treatment modality. One case of malignant melanoma arising from CGPN was identified. To ensure that all cases of malignant melanoma were identified in this cohort, a questionnaire was sent to all plastic surgeons in Ontario (n=118), and data from the Ontario Cancer Registry were reviewed using the diagnostic codes for malignant melanoma and for pigmented nevus. One case of malignant melanoma was identified in all records. Thus CGPN poses a significant management challenge to the plastic surgeon and the risk of malignancy is low.