A case of erythrokeratoderma variabilis without mutations in connexin 31

Erythrokeratoderma (EK) variabilis is a heterogeneous group of diseases cha racterized by migratory erythematous patches and hyperkeratotic plaques. Mu tations in connexin 31 have recently been found to underlie several cases o f EK variabilis. We describe a Japanese girl with extensive lesions that ap peared to be a form of EK variabilis, clinically resembling genodermatose e n cocardes (Degos). Our patient had characteristic migratory rosette or tar get-like erythematous keratotic plaques with peripheral scaling in addition to relatively fixed keratotic plaques. Sequencing of the connexin 31 gene did not detect mutations. Skin biopsy showed parakeratotic hyperkeratosis w ith hypergranulosis. Immunohistochemically, suprabasal keratins, involucrin and profilaggrin were unequivocally expressed, while loricrin expression w as greatly diminished and deiminated K1 was undetectable. Our results confi rm aetiological heterogeneity in EK. The histological features suggest disr uption of keratinocyte terminal differentiation at a very late stage.