Abstract

Cutaneous eruptions associated with hemophagocytic lymphohistiocytosis (HLH) have been reported in 6%-63% of patients. Clinical findings of these skin lesions vary widely and include maculopapular rashes, ulcers, and violaceous nodules. Corresponding histologic findings are also variable and are considered non-specific. We report the case of a 4-year-old boy who initially developed a widespread papular-pustular rash two weeks after his 12-month MMR vaccinations. These resolved with scarring then recurred following his 24-month vaccinations. Multiple skin biopsies were negative for infectious organisms and showed a granulomatous infiltrate with perforation and necrobiosis. The differential diagnosis included perforating granuloma annulare, infection or rheumatoid nodules. At the age of 4, he developed fever, hepatosplenomegaly, pancytopenia and other laboratory abnormalities requiring hospitalization. A number of studies were performed including biopsies of bone marrow and liver. Molecular testing revealed two mutations in UNC13D known to be associated with familial HLH. His prior cutaneous lesions were likely caused by immune dysregulation exacerbated by immunizations due to underlying familial HLH. This case illustrates the importance of recognizing an unusual cutaneous manifestation of a rare disease to arrive at an earlier diagnosis in a pediatric patient. Although cutaneous eruptions usually develop concurrently with other systemic symptoms of HLH, preceding atypical skin lesions may be the first indication of this rare disease.

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