Dyschromatosis symmetrica hereditaria (DSH, also known as reticulate acropigmentation of Dohi), is a rare genetic pigmentation disorder characterized by the presence of acral and facial hypo- and hyperpigmented macules. The majority of cases are familial with autosomal dominant inheritance; autosomal recessive inherited and sporadic cases have also been documented. Mutation of ADAR1, a gene involved in double-stranded RNA editing, is the underlying cause of the disease, though much about the pathogenesis remains unknown. The disorder is seen predominantly among patients of Japanese and Chinese descent, though cases have been identified among many ethnicities worldwide.

DSH typically presents in infants and young children as irregular hypo- and hyperpigmented macules 2-7 mm in diameter over the dorsal hands and feet. Hypopigmented macules develop first. Subsequently, hyperpigmented macules appear within hypopigmented areas. A reticular or mottled pigmentation pattern may result. While pigmentary changes may extend to more proximal areas of the upper and lower extremities, palms or soles are typically spared. In about 50% of cases, freckle-like macules develop on the face, and they may rarely extend to the neck and chest. By adolescence, there is no further progression of disease. The presentation of DSH may vary among members of the same family and those with identical mutations. Factors involved in this variable phenotypic expression are unknown.

In general, the condition is asymptomatic and changes in skin pigmentation are the only signs of disease. However, there have been reports of intellectual disability, developmental regression, dystonia, acral hypertrophy, and psoriasis in affected individuals.

Related topic: dyschromatosis universalis hereditaria