A skin tag, or acrochordon (pl. acrochorda), is a small benign tumor that forms primarily in areas where the skin forms creases (or rubs together), such as the neck, armpit and groin. They may also occur on the face, usually on the eyelids. Perianal skin tags can be associated with Crohn's disease. Acrochorda are generally harmless and painless and usually do not grow or change over time. Though tags up to a half-inch long have been seen, they are typically the size of a grain of rice. The surface of an acrochordon may be smooth or irregular in appearance and is often raised from the surface of the skin on a fleshy stalk called a peduncle. Microscopically, an acrochordon consists of a fibrovascular core, sometimes also with fat cells, covered by an unremarkable epidermis. However, tags may become irritated by shaving, clothing, jewellery or eczema.