Successful treatment of Darier's disease with apremilast and review of reported cases.

Darier's disease (DD) is a rare autosomal dominant genetic disorder caused by a mutation in ATP2A2, which encodes calcium (Ca²⁺) ATPase pumps in the endoplasmic reticulum. In this report, we present the first documented case in Japan successfully treated with apremilast. An 18-year-old female presented with red or brown hyperkeratotic papules and plaques on her head, neck, and chest. Histopathological examination revealed a hyperkeratotic, acanthotic epidermis, along with suprabasal acantholysis characterized by corps ronds and grains. Exome sequencing of DNA from peripheral blood mononuclear cells identified a missense mutation in ATP2A2. Based on the above results, we diagnosed her with DD despite the absence of a family history. Given the effectiveness of apremilast, a phosphodiesterase 4 inhibitor, in treating Hailey-Hailey disease (HHD), a genetically related disorder involving ATPases in epidermal calcium channels, we opted for apremilast therapy. Eight weeks post-initiation, significant improvement was observed in the patient's skin lesions on the head, neck, and chest. In this paper, we discuss the successful treatment of DD and HHD cases with apremilast, providing insights into its therapeutic potential, and offer a comprehensive review.