A case of erythrokeratoderma variabilis without mutations in connexin 31

Erythrokeratoderma (EK) variabilis is a heterogeneous group of diseases characterized by migratory erythematous patches and hyperkeratotic plaques. Mutations in connexin 31 have recently been found to underlie several cases of EK variabilis. We describe a Japanese girl with extensive lesions that appeared to be a form of EK variabilis, clinically resembling genodermatose en cocardes (Degos). Our patient had characteristic migratory rosette or target-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 with hypergranulosis. Immunohistochemically, suprabasal keratins, involucrin and profilaggrin were unequivocally expressed, while loricrin expression was greatly diminished and deiminated K1 was undetectable. Our results confirm aetiological heterogeneity in EK. The histological features suggest disruption of keratinocyte terminal differentiation at a very late stage.