All of us have had bumps, lumps, moles and blemishes on our bodies which we mostly ignore.

But in some cases, seemingly harmless spots or growths can be a sign of a serious health problem, Newsmax Health reported. 

The key is consulting your doctor when any lump or spot suddenly appears, or when an old bump or blemish suddenly changes in appearance.

“Most lumps and bumps on the skin turn out to be harmless cysts – but not all do,” said Kenneth Beer, M.D., a Palm Beach dermatologist and associate clinical professor at the University of Miami. 

“We as dermatologists see a lot of lumps and bumps that are basal cell carcinomas or squamous cell tumors. Since many of these are easily treated when removed early, it’s important to get them looked at.”

Here are lumps and bumps that can be dangerous:

Breast lumps

“Breast self-examination should be performed by every woman at least once a month,” says Erika Schwartz, M.D., a leading New York physician.

Feel for distinct lumps, areas of thickness, skin redness or distention, asymmetry, nipple inversion, or unusual nipple discharge.

While most breast lumps are noncancerous, see your doctor right away if a lump is new or unusual, the area feels different from other tissue surrounding your breast, the lump has changed — getting bigger or more defined — or you have bloody discharge from your nipple. Also look for any skin changes on your breasts like redness, dimpling, or puckering.

Testicular lumps

A man should check for testicular lumps at least once a month, says Dr. Ellen Kamhi. “The self-examination should be done ideally after a shower or bath, as the heat from the water relaxes the scrotum, which makes it easier to check for abnormalities.”

Skin spots

The Skin Cancer Foundation recommends getting an annual checkup with a dermatologist and monthly self-examinations.

Check all areas of the body — even those not exposed to the sun. This includes your scalp, palms of the hands, soles of the feet, underarms, and stomach. Use a mirror for hard-to-see places or ask someone else to check for you.

Look for:

 Asymmetry. Most melanomas, the most serious type of skin cancer, are asymmetric.

Border. Melanomas often have irregular borders with scalloped or notched edges. Normal moles usually have a smoother border.

Color. If the lump or bump is shaded brown, black, or tan and then turns red, white, or even blue, have it checked immediately. Normal moles are usually a single shade of brown.

Diameter. A melanoma is often wider than a regular mole — at least a quarter-inch in diameter.