Letterer-Siwe disease
(lĕt'ĕr-ĕr-sī'wē 
)
[Erich Letterer, Ger. physician, b. 1895; S. August Siwe, Ger. physician, 1897–1966]
The most common of three distinct histiocytosis syndromes collectively known as Langerhans cell histiocytosis, marked by proliferation of histiocytes in the viscera, bones, and skin. It is believed that this disease and the other two forms—eosinophilic granuloma of bone and Hand -Schüller-Christian syndrome—share a common pattern of granulomatous lesions with histiocyte proliferation.
The cutaneous lesions often develop during infancy or early childhood and in some cases are present at birth. These lesions include papulovesicular eruptions; inflamed, pruritic diaper area rashes; and scaly scalp lesions, all of which can be misdiagnosed as “cradle cap” (seborrheic dermatitis of the scalp) or severe diaper rash. When the disease is confined to the skin, spontaneous resolution in infancy may occur. In systemic presentations, the spleen and liver are enlarged, pulmonary infiltration is widespread, and bone marrow failure is accompanied by fever and infections. The cause of the disease is unknown.
Diagnosis: Diagnosis is based on results of a skin biopsy performed with special staining techniques.
Treatment: No specific treatment exists. Corticosteroids and antineoplastic drugs are used in the more severe forms of the disease, but many children die of pulmonary failure or overwhelming infections despite treatment.
SEE: histiocytosis, Langerhans cell.