They may be caused by infectious diseases, insect bites, or allergies. Local skin infections include boils, abscesses or cysts. Boils are infected, pus-filled swellings in the skin and may be located in or near hair follicles. They are most often found on the back of the neck, and in other moist areas of the body like the armpits and groin. Sometimes several boils form close together in a cluster called carbuncles.
Abscesses are collections of pus anywhere in the body.
A cyst is a closed sac containing either fluid or solid material. A mole is an area of the skin that is colored differently usually a dark brown. Its color comes from the same cells that give color to the skin, hair and eyes. Moles may be located anywhere on the body even on the scalp under the hair. They may vary in size and may be flat, raised or hairy.