A 37-year-old man had red or brownish papules on his face, chest, and groin, where they coalesced into plaques. Endoscopic examination revealed the presence of small xanthomatous papules on the mucous membrane of the stomach. A biopsy specimen revealed a dense infiltrate of histiocytes, foam cells, Touton giant cells, and inflammatory cells. The diagnosis of non-X histiocytosis was confirmed by immunohistochemical studies of the infiltrate.