Streptococcal Exanthem in a Blaschkolinear Pattern: Clinical Evidence for Genetic Mosaicism in Hypomelanosis of Ito


Address correspondence to Ramón Ruiz-Maldonado, M.D., Insurgentes Sur 3700-C, Mexico City, 04530 Mexico, or e-mail:


Abstract: Due to the presence of two different clones of cells in early embryogenesis, numerous congenital and acquired dermatoses have a linear distribution following the lines of Blaschko. Acquired inflammatory skin diseases are rarely observed in linear patterns. Our patient was born with macrocephaly, left eye glaucoma, and a left facial and contralateral corporal hemihypertrophy, cerebral dysgenesis, and skeletal abnormalities. Hypopigmented S-shaped linear macules on the trunk and linear streaks on the arms and legs were compatible with hypomelanosis of Ito. At 5 years of age the patient presented with an erythematous follicular exanthem compatible with scarlet fever exclusively in the lines of Blaschko. This fact suggests a genetic mosaicism.