Contributor: Gordon K. Klintworth
Letter-Siwe disease is part of the spectrum of Langerhans cell histiocytosis. It is rare acute aggressive disseminated proliferative lethal disease of Langerhans cells that affects infants <2 years old. The skin, viscera and hematopoietic system are involved. This results in hepatosplenomegaly, lymphadenopathy, myelophthisic anemia [anemia - myelophthisic], leukopenia and thrombocytopenia. The lung may be affected and multiple skin lesions that are often hemorrhagic are common. Bone lesions are not common initially. The uvea may be affected in Letterer-Siwe disease, but in contrast to other forms of Langerhans histiocytosis (Hand-Schüller-Christian disease, eosinophilic granuloma) orbital involvement is most unusual in Letter-Siwe disease. Letter-Siwe disease accounts for 10% of cases of Langerhans cell histiocytosis. Affected infants fail to thrive, become cachectic and eventually die.