RESUMEN
Giant congenital nevomelanocytic nevus (GCNN) is a rare variant of congenital melanocytic nevus measuring >20 cm in size that often has a garment-like distribution. Regular follow up is recommended because of a risk of melanoma transformation of 4.6%. We report a 14-year-old boy with gradual regression of giant congenital melanocytic nevus over the left upper limb, chest, back and axilla, whom we have followed-up since birth. At birth, a hyperpigmented jet-black patch without hair was present over the left side of torso and upper limb including palms and nails. Follow up at the ages of 1, 5, 11 and 14 years showed progressive spontaneous regression of the nevus resulting in shiny atrophic skin, diffuse hypopigmentation, lentigo-like macules, nodules and arthrogryphosis of affected areas. Histopathology of the lesions on follow-up revealed absence of pigmented nevus cells in the regressing areas and thickened sclerotic collagen bundles.