The etiology of JXG is not known. The yellowish papules and nodules of JXG represent collections of differentiated non-Langerhans cell histiocytes. JXG has been postulated to be a granulomatous reaction of histiocytes to an unidentified stimulus. Inhibition of cellular apoptosis appears to play a minor role in the growth of xanthogranulomas. The appearance of giant cells and foamy, lipid-laden histiocytes occurs late, and apparently are secondary events, possibly in response to cytokine production by histiocytes.
Serum lipids are normal and remain normal.
JXG occurs in Caucasians about 10 times more frequently than in blacks. Patients usually present in infancy or early childhood with an asymptomatic, smooth, round, yellow papule or papules. Lesions usually are asymptomatic. Mucous membrane, tongue, and palm and sole involvement are rare. A papular and nodular form of JXG has been described.