Gianotti-Crosti syndrome presenting as lichenoid dermatitis.

Papular acrodermatitis of childhood (Gianotti-Crosti syndrome) is an uncommon, self-limited disease characterized by an erythematous papular eruption symmetrically distributed on the face and limbs and mild lymphadenopathy, thought to be of viral origin. The histopathologic findings are nonspecific and include focal parakeratosis, mild spongiosis, superficial perivascular infiltrate, papillary dermal edema, and extravasated red blood cells. Interface changes with some basal vacuolization may be present, but are not a conspicuous feature. We present a 2 1/2-year-old boy with multiple papules and plaques on the face and extremities and cervical lymphadenopathy. Histopathologic analysis showed compact orthokeratosis, focal parakeratosis, hypergranulosis, psoriasiform epidermal hyperplasia, and a dense lichenoid lymphohistiocytic infiltrate with extensive exocytosis of mononuclear cells. Immunoperoxidase staining with CD 1 a revealed clusters of Langerhans cells in the epidermis and in the papillary dermis. In view of the clinical findings, a diagnosis of Gianotti-Crosti syndrome was made. Although there are a few reports describing a lichenoid pattern of infiltration in Gianotti-Crosti syndrome, this histologic pattern is not widely known. This case is presented to illustrate the fact that Gianotti-Crosti syndrome can present as lichenoid dermatitis, and, especially in children, should be added to the differential diagnoses of lichenoid infiltrates.