is a type of histiocytosis
(a condition where histiocytes
proliferate in the body.) It is sometimes classified as a form of Langerhans cell histiocytosis
, or as a form of histiocytosis X
. It is most commonly seen in children less than two years old.
It is named for Erich Letterer and Sture Siwe.
Symptoms include lymphadenopathy
, and seborrhea
-like lesions on the skin.
Untreated, the disease is fatal. The five-year survival rate with treatment is fifty percent.