Giant congenital pigmented naevus or giant hairy naevus

Giant congenital pigmented naevus or giant hairy naevus

This hamartoma of naevo-melanocytes causes confusion because its definition and management are contentious. It has a similar histology to compound naevi, but with naevus cells distributed variably throughout all skin layers and into the subdermal fat and muscle and with a tendency to dermatomal distribution ( Figure 45.28 ). Giant congenital pigmented naevi (GCPNs) are precursors of melanoma but the magnitude of this risk is unclear, largely because of the lack of well-conducted studies and variable classification of the naevus. A 3–5% lifetime risk of melanoma is quoted. One in three childhood malignant melanomas arise in patients with GCPN, but the risk decreases with age: 15% of malignant melanomas present at birth, 62% present by puberty and 99% by 45 years of age. A multidisciplinary management approach is advocated, with initial investigations examining for neurocutaneous mela - nosis as there may be leptomeningeal involvement. Remov al of ed for both aesthetic and oncological GCPN should be consider reasons.