A case of adult blaschkitis with features of interface dermatitis

Abstract

Conflicts of interest: none declared. Sir, Adult blaschkitis is a rare, relapsing linear eruption of pruritic papules and vesicles. The lesions involve multiple sites, particularly the trunk, and follow Blaschko’s lines.1 2–3 Blaschkite de l’adulte and acquired relapsing self‐healing Blaschko dermatitis have been suggested as alternative names for this condition.1, 2 Seven cases have been reported in the literature since it was first described in 1990 by Grosshans and Marot, and the histopathological findings were those of spongiotic dermatitis.1 2–3 We present a case of adult blaschkitis with the histopathological features of interface dermatitis. A 31‐year‐old man presented with a 1‐month history of unilateral pruritic skin disease. He had no history of atopic dermatitis, psoriasis, or any other dermatitis. He had no significant past medical or drug use history. Physical examination revealed discrete erythematous grouped papules and vesicles on the left sides of the trunk and upper and lower limbs. The skin lesions formed whorls and streaks along Blaschko’s lines (Fig. 1). A punch biopsy from an abdominal lesion revealed hyperkeratosis, focal parakeratosis, acanthosis, and scattered dyskeratotic cells with basal cell vacuolar degeneration in the epidermis. Spongiosis and lymphocyte exocytosis were also found. Superficial perivascular lymphocytic infiltrates were seen in the dermis (Fig. 2). A short course of oral corticosteroids (20 mg daily) and topical corticosteroid lotion were prescribed. The existing skin lesions improved; however, new lesions developed. His skin lesions cleared with the addition of narrowband ultraviolet B phototherapy (total 6250 mJ, twice a week for 2 months).