CLINICAL-DIFFERENTIATION BETWEEN PROTEUS-SYNDROME AND HEMIHYPERPLASIA- DESCRIPTION OF A DISTINCT FORM OF HEMIHYPERPLASIA

Proteus syndrome is a rare and highly variable hamartomatous syndrome that can affect multiple organ systems. It is characterized by hyperpl astic lesions of connective tissue, vascular malformations, linear ver rucous epidermal nevi, and hyperostoses. The cause of the disorder is unknown, but the current working hypothesis is that it is caused by a mosaic alteration that leads to a highly variable phenotype, equal sex ratio, sporadic occurrence, and discordant mono zygotic twins. Herein we describe our experience with 18 patients with a referring diagnosi s of Proteus syndrome. It was found that imaging studies are very usef ul for the characterization of the syndrome. One finding was that sple nic hyperplasia can be a manifestation of Proteus syndrome. Analysis o f the clinical data shows that Proteus syndrome is frequently confused with ''hemihyperplasia.'' A distinct subtype of hemihyperplasia is de fined that includes static or mildly progressive hemihyperplasia and m ultiple lipomata, (C) 1998 Wiley-Liss, Inc.(dagger)