An epidermoid cyst is a small, harmless lump that forms beneath the skin, usually on the face, neck, or trunk. It is characterized by a round bump under the skin, a tiny blackhead blocking the opening of the cyst, yellow discharge from the cyst, and, if it becomes inflamed or infected, redness, swelling, and tenderness in the affected area. While anyone can develop these cysts, individuals who have reached puberty, those with specific genetic disorders, and those who have experienced skin injuries are more prone to them.
Epidermoid cysts are often mistaken for sebaceous cysts and can also occur due to damage to hair follicles or the outer layer of the skin. These slow-growing lumps are typically painless, but if they become painful, rupture, or get infected, it may be necessary to remove them.