Throughout your life you've probably noticed various bumps coming and going on your skin. When you're younger these bumps can be acne, an allergic reaction or an infection like the chicken pox. However, there is a skin condition known as xanthoma that may be masquerading as acne or an allergic reaction. This exotic-sounding affliction is actually pretty common. Xanthomas are bumps that form when fat collects in pockets under the skin, and usually occurs in those over the age of 40. These bumps can pop up anywhere on your body but are most frequently found near the eyes, hands, feet and joints [sources: Lehrer, Fair].
Xanthomas are usually painless, but they can be unsightly. These bumps often appear yellow to red in color, occur in clusters and come in a variety of sizes, ranging from very small to larger than several inches. There are several types of xanthomas and each has it's own specific features and locations. The most common kind of xanthoma is xanthelasma palpebrarum which usually appears as a yellow, velvety bump on the eyelids. Tuberous xanthomas are firm, reddish-yellow bumps that usually form on pressure areas like the elbows and knees. Eruptive xanthomas are also red-yellow in color and these often occur in clusters on the buttocks or shoulders. Unlike most xanthomas, this type can be painful and itch. [source: Fair]. Because of their specific features and locations, xanthomas are often diagnosed by physicial exam but a biopsy can confirm a diagnosis if there are any doubts.
Although xanthomas themselves do not pose a medical threat, they are usually a sign of another medical disorder, so notify your doctor if think you spot one. Often their presence is due to a problem metabolizing lipids, or fats. When lipids aren't metabolized quickly enough, they can coalesce underneath the skin as xanthomas [sources: Lehrer, Fair]. Because a lipid disorder could be a serious threat to your health, discussing xanthomas with your doctor is very important.
You might be wondering what causes xanthomas. To learn more about the metabolic disorders that cause xanthomas, read on.