Finding a new lump or bump on your body would give most of us pause. After all, a lump can, in rare cases, mean cancer. But not every bump or lump should cause concern or worry.

To get a better understanding of when something new is worth talking to your doctor about, we spoke with orthopedic surgeon Nathan W. Mesko, MD.

Are all lumps cause for concern?

The good news is that a majority of these lumps are harmless and not a cause for concern. A number of skin or medical conditions can cause lumps and bumps to appear on the surface or just below the skin.

When not to worry

Lumps that are not a cause for concern have some distinctive characteristics.

Not-so-serious lumps usually are:

• Soft.
• Mobile, meaning it moves and changes form when you touch it.
• Located in the superficial or fat layer of skin.
• Grow large and painful with activity, and diminish in size with rest.

Lumps connected to exercise

“One major marker is if you can connect the lump’s appearance to a specific trauma or activity,” says orthopedic surgeon Dr. Mesko. Athletes of all levels experience the occasional bump as a result of exercise, training, competition or other physical activity, he adds.

“In that case, we recommend you follow the basic RICE method: rest, ice, compression and elevation,” Dr. Mesko says. “If, over time, the lump or swelling improves, that’s a reassuring sign that it is harmless and nothing to worry about.”

Cysts

One of the most common conditions that cause lumps, bumps or swelling are cysts. Some common cysts include Baker’s cysts, a fluid-filled bulge that forms behind the knee and ganglion cysts, rounded lumps filled with a jelly-like fluid that can develop on tendons and joints.

When to see a doctor

In rare cases, an unexplained lump, bump or swelling can be a sign of a more serious issue beneath the skin.

Bumps that are cancerous are typically large, hard, painless to the touch and appear spontaneously. The mass will grow in size steadily over the weeks and months. Cancerous lumps that can be felt from the outside of your body can appear in the breast, testicle, or neck, but also in the arms and legs.

Adult soft tissue sarcoma

One type of cancerous lump that can form almost anywhere in the body is called adult soft tissue sarcoma. The soft tissues of the body include the muscles, tendons (the bands of fiber that connect muscles to bones), fat, blood vessels, lymph vessels, nerves and the tissues around joints.

Most frequently, though, adult soft tissue sarcoma develops in the legs, arms, chest or the area behind the abdomen called the retroperitoneum, says oncologist Dale Shepard, MD, PhD.

“Adult soft tissue sarcoma is a disease in which malignant cells form in the soft tissues of the body,” he says. “In the early stages, it rarely causes symptoms because the tumors often are located deep in the tissue.”

Soft tissue sarcomas can grow to be quite large before causing symptoms because they often are embedded deep in the body, Dr. Shepard says.

Most commonly, soft tissue sarcomas feel like masses or bumps, which may be painful. If the tumor is in the abdomen, it may produce nausea or a sensation of fullness as well as pain, he says.

Adult soft tissue sarcoma is rare. Among adults, they represent less than 1% of all cancers, Dr. Shepard says.

Other causes

Other conditions can cause swelling leading to new lumps, too. While these may not be associated with an emergency condition, they’re worth monitoring and discussing with your healthcare provider:

• Tendinitis.
• Swollen lymph nodes, especially when accompanied by inflammation or infection.
• Rheumatoid arthritis.

It’s important to talk with your doctor about any lumps that are larger than two inches (about the size of a golf ball), grow larger, or are painful regardless of their location.

“Tell your doctor about new lumps or other symptoms that cannot be explained or that don’t go away in a few weeks,” Dr. Shepard says.