Finding a lump on your neck, back, or behind your ear can be alarming—especially if it appears suddenly or feels unfamiliar. While many lumps are harmless, others may signal an underlying medical condition that needs attention.

These lumps can vary widely in size, texture, and cause. Some disappear on their own, while others persist or grow over time. Understanding what may be behind a lump is key to knowing how to care for it and when to seek medical advice.

An epidermoid cyst is a common, benign (non-cancerous) growth that forms just beneath the skin. These cysts are usually slow-growing and can appear almost anywhere on the body, though they are most often found on the neck, back, face, or behind the ears.

They develop when skin cells that normally shed become trapped beneath the skin’s surface. These cells continue to multiply and form a sac filled with keratin, a thick protein also found in hair and nails.