xanthoma

Xanthoma is a lesion characterized by deposition of lipid-laden histiocytes in the skin or subcutaneous tissue, producing yellowish plaques or nodules. It is commonly related to disorders of lipid metabolism, especially hyperlipidemia, though some forms occur with cholestasis, diabetes mellitus, thyroid disease, or in rare genetic disorders.

Xanthomas are categorized by appearance and location. Xanthelasma are soft, yellow plaques around the eyelids. Tendinous xanthomas are firm nodules over tendons, notably the Achilles and hands. Tuberoeruptive/xanthomas are nodules on elbows, knees, buttocks; eruptive xanthomas present as crops of small yellow papules with erythematous rims on the trunk and extremities, often with pruritus, associated with marked hypertriglyceridemia. Plane (flat) xanthomas are flat lesions on the eyelids, trunk, or other surfaces and can associate with cholestasis or familial lipid disorders.

Pathophysiology involves deposition of cholesterol-rich lipids within dermal macrophages (foam cells) and sometimes Touton-type giant cells. Lesions reflect long-standing lipid imbalance rather than a direct tumor.

Clinically, they present as yellowish, sometimes translucent plaques or nodules. Xanthelasma are cosmetic concerns; tendinous and tuberoeruptive lesions may be signs of systemic lipid disorders and cardiovascular risk.

Diagnosis relies on clinical appearance and lipid testing; histology shows foamy histiocytes in dermis; a skin biopsy is rarely needed but can confirm.

Management focuses on treating the underlying lipid abnormality with statins, fibrates, PCSK9 inhibitors, or newer agents, along with lifestyle modifications. Local treatment for prominent lesions includes laser therapy, surgical excision, or curettage. Prognosis depends on the underlying lipid disorder; cutaneous lesions may persist or recur even after lipid control, but cardiovascular risk can be reduced with appropriate therapy.