- Xanthomas represent focal collections of lipid-laden macrophages and can occur within the dermis or tendons. Most occur due to derangements in lipid metabolism, and different subtypes are associated with disorders in the metabolism of different lipid molecules.
- Substantial serum excess of lipid levels, either due to inborn errors of metabolism or acquired diseases of the hepatobiliary system, can yield xanthomas. However, the "Xanthelasma" subtype is frequently not associated with any gross disorder of lipid levels.
- Xanthomas appear as multiple yellowish papules. The xanthelasma subtype, not necessarily associated with lipid-level derangements, occurs on the eyelids. Tendon xanthomas present as hard nodules in tendons and their yellow color cannot be appreciated due to their depth. Histologically, xanthomas represent focal collections of foamy macrophages laden with lipid.
- Other than the xanthelasma subtype which may be benign, xanthomas represent inherited or acquired derangements of lipid metabolism. They typically resolve when the underlying lipid disorder is corrected, although the kinetics of resolution depend on the subtype.