Noticing a bump, lump, or unusual growth on the back of your head can naturally cause concern, but there are several possible explanations, and many are harmless. A common cause is a **pilar cyst**, which can develop around a hair follicle and appear as a smooth, firm lump beneath the skin. Other possibilities include an **inflamed hair follicle, ingrown hair, lipoma**, or a swollen lymph node. In some cases, irritation from hairstyles, hats, sweating, or minor skin injuries can also contribute to a noticeable area on the scalp.

The appearance and sensation of the growth can provide useful clues. A harmless cyst or lipoma may grow slowly and remain relatively painless, while an irritated follicle or skin infection may become red, tender, swollen, or warm. Some scalp growths can also develop a crust, change in appearance, bleed, or become uncomfortable. Because different conditions can look similar, it is difficult to determine the exact cause simply by looking at a description or photograph.

If a growth on the back of your head is **new, rapidly increasing in size, painful, repeatedly bleeding, infected-looking, or not going away**, it is a good idea to have it examined by a healthcare professional or dermatologist. Avoid squeezing, cutting, or trying to remove it yourself, as this can cause irritation or infection. A professional examination can help identify what the growth is and whether any treatment is necessary.