DYSCHROMATOSIS

The dyschromatoses are a group of disorders characterized by the prese nce of both hyperpigmented and hypopigmented macules, many of which ar e small in size and irregular in shape, There are two major forms-dysc hromatosis symmetrica hereditaria (DSH) and dyschromatosis universalis hereditaria (DUH), both of which are seen most commonly in Japan, DSH was first described by Toyama in 1929 and is characterized by a symme trical distribution of hyperpigmented and hypopigmented macules on the extremities, especially over the dorsa of the hands and feet, In 1933 , Ichikawa and Hiraga were the first to describe DUH as well demarcate d brown macules admired with various sized hypopigmented macules in a generalized as opposed to acral distribution. DUH was noted to appear within the first month of life. Some clinicians have suggested that DS H might be a subtype of DUH; however, we have to wait for the cloning of the causal genes of these diseases before coming to any definite co nclusions, The differential diagnosis of dyschromatosis includes xerod erma pigmentosum, dyschromic amyloidosis, and exposure to chemicals su ch as diphenylcyctopropenone and monobenzyl ether of hydroquinone. Cop yright (C) 1997 by W.B. Saunders Company.