A small lump under the skin can be surprisingly alarming, especially when you notice it unexpectedly. However, many lumps are caused by harmless conditions such as cysts, fatty growths called lipomas, or temporarily swollen lymph nodes. The appearance of a lump alone usually isn’t enough to determine what caused it.

A lipoma, for example, is a common type of fatty lump that usually grows slowly. It tends to feel soft or rubbery and may move slightly when you press it. Most lipomas are harmless and don’t require treatment unless they become painful, bothersome, or continue growing.

Cysts can also create small bumps beneath the skin. Some contain fluid or other material and may remain unchanged for a long time. Other lumps may be swollen lymph nodes, particularly around the neck, under the chin, armpits, or groin. Lymph nodes commonly become enlarged when the immune system is responding to an infection.

The important thing is to pay attention to changes. A lump that suddenly becomes larger, increasingly painful, red, warm, or swollen may need medical evaluation. These changes can sometimes indicate inflammation or infection rather than a simple harmless growth.

You should also have an unexplained lump checked if it persists or continues growing. Lymph nodes that remain enlarged for several weeks, feel unusually hard or rubbery, or don’t move when pressed deserve particular attention.

Certain characteristics are more concerning than others. A rapidly growing, firm lump that feels fixed in place should not simply be ignored. This doesn’t automatically mean cancer, but a healthcare professional may need to examine it and determine whether further testing is appropriate.

Trying to squeeze, puncture, or repeatedly press a mysterious lump isn’t a good idea. Doing so can irritate the area or introduce infection. Instead, note its approximate size, location, tenderness, and whether it changes over time.

Most small lumps turn out to have relatively ordinary explanations, but there is no reliable way to diagnose every lump by appearance or touch alone. If you’re uncertain about a new or changing lump, having it examined by a healthcare professional is the safest way to understand what you’re dealing with.