The designation histiocytosis X was coined as a unifying diagnostic term by Lichtenstein to draw attention to the pathological unity made up of several diverse and transitional syndromes, ie, eosinophilic xanthomatous granuloma, Hand-Schüller-Christian syndrome and Letterer-Siwe disease. Lichtenstein preferred the terms localized, chronic disseminated, and acute disseminated histiocytosis X to represent these related entities. A 40-year-old white man presented with localized histiocytosis X which progressed to a chronic disseminated form of the disease that could not be distinguished from Hand-Schüller-Christian disease. Almost complete resolution of this very resistant tumor occurred following treatment with vinblastine sulfate.
Siegel JS, Coltman CA. Histiocytosis X: Response to Vinblastine Sulfate. JAMA. 1966;197(6):403-406. doi:10.1001/jama.1966.03110060077019