[Lichen pemphigoid associated with developing hepatitis B in a child].

INTRODUCTION: Lichen planus pemphigoides is a rare acquired auto-immune bullous dermatosis which usually affects adults. Only four cases have been reported in children. We describe a new case of lichen planus pemphigoides in a child unusual by its association with an evolutive hepatitis B and by the occurrence of a lichen planus relapse. CASE REPORT: A 10-year-old African boy has been seen for a pruritic dermatosis with papular lichenoid lesions on the trunk and the limbs and blisters on the lower limbs, both arise on lichen planus lesions and normal skin. The diagnosis of lichen planus pemphigoides was confirmed by histology which showed the features of lichen planus on a papule and of a sub-epidermal split on a bulla and by direct and indirect immunofluorescent studies which revealed an IgG and C3 linear deposit at the dermo-epidermal junction and the presence of circulating IgG anti-basement membrane zone antibodies. Laboratory investigations showed an evolutive hepatitis B (HBsAg +). Healing was obtained by dapsone and topical steroid therapy. Eight months after withdrawal of treatment the patient presented a non-bullous relapse of lichen planus. The histology showed a typical aspect of lichen planus and the immunofluorescence studies were negative. The hepatitis B serology was unchanged. The lesions rapidly improved with topical steroid and coaltar. One year later the patient exhibited few slight lichen planus lesions on the limbs and the hepatitis B serology showed the onset of sero-conversion. DISCUSSION: Lichen planus and lichen planus pemphigoides are probably variants of the same disease. Their successive occurrence in our case report favours this hypothesis as does the association with an hepatitis B.