Nonprogessive size reduction of limbs involved in giant congenital nevi: A magnetic resonance imaging study.

Giant congenital nevi are hamartomas of neuroectodermal origin predominantly involving the trunk; two or more body segments are also commonly involved. A feature observed when giant congenital nevi are involved in a limb is a nonprogressive reduction in limb size. This feature has been evaluated, and demonstrates alterations only in the skin and subcutaneous tissue of the affected limb, with all other structures normal compared with the unaffected contralateral limb. The present magnetic resonance imaging study clearly demonstrates the substitution of subcutaneous tissue and fat cells by nevus cells, leading to a dramatic volume reduction in these tissues. The volumes of the deeper structures were not affected.