Type 2 segmental manifestation of Hailey-Hailey disease: poor therapeutic response to dermabrasion is due to severe involvement of adnexal structures

In autosomal dominant skin conditions, two different types of segmental man ifestation can be distinguished. Type 1 represents heterozygosity for a pos tzygotic mutation, resulting in a degree of severity similar to that of the nonmosaic phenotype. Type 2 reflects loss of heterozygosity and shows an e xcessively pronounced involvement superimposed on the ordinary nonsegmental phenotype. We describe the clinical, histopathological and therapeutic asp ects of the first case of type 2 segmental manifestation of Hailey-Hailey d isease (HHD). A 24-year-old woman with a family history of HHD comprising f our generations, presented with lesions of erythema and blistering arranged in a unilateral pattern following the lines of Blaschko. The disorder was first noted at the age of 3 months. At the age of 24 years, additional scat tered symmetrical lesions involving the axillary and inguinal folds were no ted. Histopathological examination of the severely involved linear skin are as revealed pronounced acantholysis within the deep adnexal structures, whe reas clinically unaffected skin showed the typical histopathological featur es of the heterozygous phenotype with suprabasal clefting and acantholysis sparing the adnexae. Dermabrasion was performed in the areas of segmental i nvolvement. During a follow-up period of one year, no recurrence was noted, but 18 months after dermabrasion a recurrence was present in the left subm ammary and left perianal regions. This therapeutic resistance to dermabrasi on may be explained by the presence of acantholysis within the adnexal stru ctures of the skin as found in type 2 segmental HHD.