Severe congenital systemic juvenile xanthogranuloma in monozygotic twins.

Juvenile xanthogranuloma, a histiocyte disorder, usually presents with a solitary cutaneous lesion. Juvenile xanthogranuloma with extracutaneous involvement is a rare disease in which significant morbidity and occasional deaths may occur. Monozygotic twins with congenital systemic juvenile xanthogranuloma who presented with multiple skin lesions, hepatosplenomegaly, liver failure, and bone marrow involvement were reported. The diagnosis of systemic juvenile xanthogranuloma was confirmed by histology and immunohistochemical stains of the skin with liver biopsies revealing dense infiltration of lymphohistiocytes with typical Touton giant cells staining positive for CD68 and negative for CD1a and S-100 protein. Both of them received systemic prednisolone 1 mg/kg/day which was gradually tapered off with time according to clinical and investigative responses. At the 17-month follow-up period, both patients showed remarkable regression in all symptoms and laboratory studies.