These lumps can vary in size and appear for many different reasons, ranging from minor skin issues to more serious conditions that require medical attention. Understanding why a lump has appeared can help you decide whether it’s something to simply monitor or something that needs prompt evaluation.
A common and usually harmless cause: epidermoid cysts
One of the most common and typically harmless causes of a lump beneath the skin is an epidermoid cyst. These cysts develop when skin cells fail to shed properly and instead accumulate beneath the surface.
Over time, this buildup forms a small, slow-growing bump filled with keratin, a natural substance found in skin, hair, and nails. Epidermoid cysts often appear on the neck, back, or behind the ears and may remain the same size for years.
1. When cysts become a problem
Epidermoid cysts are usually painless and feel smooth and round to the touch. However, problems can arise if a cyst becomes irritated or infected. In those cases, it may turn red, swell, become tender, or begin to drain a thick, foul-smelling discharge. If this happens, it’s best to consult a doctor.