This 5-year-old boy had a brown, hairy plaque on his back since birth. A magnetic resonacne imaging study revealed no leptomeningeal involvement. Due to the large size of the lesion, surgical excision was not felt to be a viable option. He had five phenol peel which resulted in significant lightening of the lesion. Subsequent peels gave little improvement, and treatment was discontinued. Giant congenital nevus (giant hairy nevus, bathing trunk nevus) is an uncommon entity, and is estimated to occur in between 1 in 20,000 and 1 in 500,000 live births. It is characterized by a large, hairy patch or plaque, occurring predominantly on the trunk, and often with satellite lesions. These nevi may follow a segmental distribution.
The chief concern in children and adults with these giant nevi is the potential for the development of melanoma either within the nevi or within the central nervous system. Approximately 5 percent of individuals with these lesions go on to develop melanoma, and these melanomas account for approximately 40 percent of all the melanomas seen in children. For this reason, surgical extirpation of these nevi is sometimes recommended, when feasible, and otherwise close clinical follow-up is recommended. Still, two-thirds of melanomas occurring in these nevi start in nonepidermal sites making early detection challenging.
A recent survey-based study has suggested that large congenital melanocytic nevi that have a larger number of satellite lesions are associated with an increased risk of neurocutaneous melanocytosis. Those on the posterior axis may also be associated with a somewhat increased risk of neurocutaneous melanocytosis. Overall, less than 10 percent of the patients included in this study had neurocutaneous melanocytosis, which may be associated with the development of hydrocephalus as well as leptomeningeal melanoma.
Management of these giant nevi revolves around both clinical follow-up in order to attenuate the risk of significant morbidity and mortality from potential melanoma as well as cosmetic management. In patients with smaller nevi, excisional surgery is sometimes effective, and can be staged in order to approach a better cosmetic outcome. This may also help reduce the risk of developing a melanoma within the nevus. In this patient, phenol peels were performed in order to lighten the lesion.
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large, geographic, brown hairy plaque with areas of hypopigmentation and scattered light brown macules