FAMILIAL PITYRIASIS-RUBRA-PILARIS

Background: Familial pityriasis rubra pilaris is a rare autosomal domi nant skin disorder. Four individuals from one family are described who demonstrate clinical features compatible with a diagnosis of familial pityriasis rubra pilaris. Results of light and electron microscopic, immunocytochemical, and biochemical analysis of skin biopsy specimens from three of these four individuals are presented. Observations: All affected individuals demonstrated erythematous scaly skin with follicu lar prominence and islands of sparing. Inheritance was consistent with an autosomal dominant trait. Light and electron microscopic findings were compatible with those reported in sporadic cases of pityriasis ru bra pilaris. Immunocytochemistry showed suprabasal staining with monoc lonal antibody AE1. Immunoblot analysis revealed abnormal keratins wit h K6/16 expression, the possibility of an abnormal K14 or K16, and a 4 5-kd acidic keratin not normally expressed in epidermis. Because simil ar biochemical analyses have not been reported previously in other cas es of pityriasis rubra pilaris (familial or sporadic), comparisons can not be made. Conclusions: The observations suggest that the cutaneous abnormality in this family extends beyond clinical and morphological a lterations to abnormalities in biochemical markers of epidermal differ entiation.