As postulated, JXG may 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 is a secondary event, possibly in response to cytokine production by histiocytes. Serum lipid levels are normal and remain normal. JXG occurs in Caucasians approximately 10 times more frequently than in blacks.
Equal incidence occurs in adult males and females.
Patients usually present in infancy or early childhood with an asymptomatic, smooth, round, yellow papule or papules. Lesions usually are asymptomatic. Involvement is rare on mucous membranes, the tongue, palms, and soles. Both papular and nodular forms of JXG have been described. Coexistence of caf au lait macules has been associated with epilepsy.