Mosaic trisomy 7 in a patient with pigmentary abnormalities.

Somatic chromosomal mosaicism may present as isolated pigmentary abnormalities or multiple congenital anomalies with mental retardation. Pigmentary lesions are visually dramatic and are differentiated based on appearance when the underlying pathogenesis is not known. It is now clear that mosaicism is responsible for the pigmentary findings in hypomelanosis of Ito (HI) and linear and whorled nevoid hypermelanosis (LWH). Both hypopigmentation and hyperpigmentation have been noted in the same individual, and both LWH and HI can be caused by similar chromosomal abnormalities. Both of these conditions exhibit similar systemic involvement. We present a case of LWH associated with mosaic trisomy 7 and review the relevant literature.