Though there are a number of different conditions that can cause them, small, raised skin bumps often appear as a result of a hereditary disease, an allergic reaction, infection or acne, according to Healthline. Some other possible causes include skin conditions such as cysts, dermatofibromas, folliculitis and epidermoid cysts, reports WebMD.
Most bumps require no treatment if they do not cause discomfort, explains Healthline. The most common causes of skin bumps tend to be benign. Warts, angiomas, insect bites, keloids and mollusca are conditions that cause raised bumps. Warts are hard, rough bumps usually found on the feet and hands. Angiomas are collected blood vessels that form a raised spot under the skin.
Keloids are raised, irregularly shaped scars, says MedicineNet. A mild, contagious skin disease called molluscum contagiosum can result in pink raised nodules. Contact dermatitis, a raised skin rash, occurs when the skin is exposed to a substance that produces an allergic skin response. Skin bumps can also be the result of erythema nodosum, a type of skin inflammation that causes painful lumps usually found below the knees.
Cysts are closed pockets of tissue usually filled with pus or fluid, states WebMD. Patients report that cysts feel like large peas under the skin's surface. A keratoacanthoma, which feels like a thick growth, tends to appear on areas that suffered sun damage. A harmless skin disorder called keratosis pilaris appears as small, white or red bumps on the upper thighs, arms, cheeks or back.