Melanoma Arising After Excision of Giant Congenital Nevus

Mary Wu Chang, MD

Melanoma can develop at any age, so patients with GCMN should be followed by dermatology.

Congenital melanocytic nevi are common birthmarks categorized by size as small, intermediate, large, and giant. Giant congenital melanocytic nevi (GCMN) (projected adult size, >20 cm) are rare, occurring in 1 in 500,000 births. In addition to having psychosocial consequences, GCMN can be complicated by neurocutaneous melanosis, melanoma, or both, often aggressive and usually occurring before age 6. The melanoma can arise in the nevus or elsewhere. Excision typically requires multiple staged procedures, often with tissue expansion, flaps and grafts, and scarring is usually extensive.

This case report describes a man in his 40s who underwent 10 staged excisions with split-thickness skin grafts in childhood to remove a GCMN. Thirty-four years after surgery was completed, he developed a 2 cm subcutaneous tender nodule beneath a well-healed skin graft on the posterior thigh. The biopsy showed metastatic melanoma; subsequent imaging showed no metastases, but sentinel lymph node biopsy was positive in the inguinal nodes.

Citation:

Coughlin CC et al. Malignant melanoma arising at the site of a previously excised giant congenital melanocytic nevus. JAMA Dermatol 2013 Nov 27; [e-pub ahead of print].