A Mysterious Case of Bumps on the Beach

Sandy and Clark are 10- and 11-year-old brothers with a one- to two-day history of non-pruritic erythematous bumps on their abdomens.

Physical examination: Multiple papules that abruptly cut off at the waistline…not lichenified, or at least not yet.

Erythematous papular lesions on the abdomens of two young boys, that cut off abruptly at the waistline

Close up of rash on Clark's abdomen.

Close up of rash on Sandy's abdomen.

Recap of current information: The boys are at the beach, having fun; kids’ work is their play, so we’re taking an "occupational history" of sorts.

Diagnosis: Boogie Board Dermatitis

Boogie Board

Frictional lichenoid dermatitis is the technical name for this boogie board eruption, aka, juvenile papular dermatitis and recurrent summertime pityriasis of the elbows and knees.

Characterized by aggregates of discrete lichenoid papules that are 1-2 mm in diameter; secondary to frictional trauma.

Frictional lichenoid dermatitis in a four-year-old who spent a lot of time playing in the sandbox.

Frictional lichenoid dermatitis on the knees of a four-year-old.

Differential diagnosis: Psoriasis, guttate psoriasis, Gianotti-Crosti syndrome (papular acrodermatitis), lichenoid drug eruptions.

Drugs associated with lichneoid eruptions: diuretics, beta-blockers, antimalarials, phenothiazines, acetylsalicylic acid, carbamazepine, chlorpropamide, enalapril.

Drugs associated with lichneoid eruptions: gold, iodides, levamisole, mercury, methyldopa, norflex, penicillamine, others.

Treatment of frictional lichenoid dermatitis: generally resolve without treatment but topical steroids, keratolytics with lactic acid or urea may be considered.