Contributor: Gordon K Klintworth
Xanthelasma is a localized xanthomas of the eyelid composed of xanthoma cells that are situated predominantly around the blood vessels and adnexal structures of the papillary dermis and reticular dermis of the superficial skin. Xanthelasma almost never extends into the subcutis. It appears as a soft flat or slightly elevated, yellowish-tan plaque usually on the inner canthus of the eyelids of both eyes. Both the upper and lower eyelids are commonly affected by this commonest cutaneous xanthoma. Xanthelasma is seen mainly in middle-aged or elderly patients and hyperlipidemia is sometimes associated. It can occur with familial hypercholesterolemia and in individuals with all five subtypes of essential hyperlipidemia [hyperlipidemia - essential] (especially hyperlipidemia type II and hyperlipidemia type III)and in persons with secondary hyperlipidemia [hyperlipidemia - secondary] (diabetes mellitus, primary biliary cirrhosis [cirrhosis - primary biliary]). However, ~67% of individuals with xanthelasma are normolipemic. Sometimes xanthelasmas are excised for cosmetic reasons. A xanthelasma is characterized microscopically by xanthoma cells with small round nuclei and abundant clear cytoplasm. The foamy macrophages result from the dissolving of lipid in the alcohol used during tissue processing. Oil red O stains the intracytoplasmic lipid within fresh frozen tissue. Fibrosis and an inflammatory cell infiltrate are minimal. Xanthelasma needs to be distinguished from other conditions with foamy macrophages, such as necrobiotic xanthogranuloma  [xanthogranuloma - necrobiotic], Erdheim-Chester disease lepromatous leprosy [leprosy - lepromatous].