Derm Dx: Warty plaques in a unilateral pattern

A 13-year-old boy presents with nonpruritic, hyperpigmented warty papules and plaques. They are arranged in a unilateral pattern on the left side of his lower abdomen. He has had them since the age 1 year. Previously they were flat and tan, but they have become more extensive, thicker, and darker. They are limited to the left lower abdomen area of ...