Finding a lump on your neck, back, or behind your ear can be unsettling, especially if it appears suddenly. While many lumps are harmless, some may signal an underlying condition that needs medical attention. Understanding common causes can help you decide when to monitor and when to seek care.

One of the most common causes is an epidermoid cyst, a benign growth that forms just beneath the skin. These cysts usually grow slowly and often appear on the face, neck, back, or behind the ears. They develop when skin cells become trapped instead of shedding normally.

Inside an epidermoid cyst is keratin, a thick protein found in hair and nails. Most cysts are painless and harmless, but they can become inflamed or infected, causing redness, swelling, tenderness, or foul-smelling discharge.

Risk factors include blocked pores, minor skin injuries, acne, and certain genetic conditions such as Gardner syndrome. Adults, particularly men, develop these cysts more often than children.

Typical symptoms include a smooth or slightly firm lump that is skin-colored and movable. If infection occurs, the area may feel warm, painful, or swollen. Doctors usually diagnose cysts through a physical exam, though imaging or a biopsy may be needed if features are unusual.

Trying to pop or drain a cyst at home can cause infection, scarring, or worsening inflammation. Some home remedies may irritate the skin and should be avoided if discomfort occurs.

Medical evaluation is important if a lump grows quickly, changes shape or color, becomes painful, or is accompanied by fever or unexplained weight loss. Early assessment helps rule out more serious conditions.

While cysts can’t always be prevented, gentle skincare, avoiding skin trauma, and not squeezing blemishes can reduce risk. Most cysts are harmless, but changes should never be ignored—when in doubt, seek professional advice for peace of mind.