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Skin Lump


  • A skin lump or bump covered by normal skin
  • Skin swelling just in one spot (localized) is also included

Causes of Skin Lumps

  • Insect Bites. The most common cause of an itchy bump is a mosquito bite. Other insects can also cause little bumps.
  • Stings. A bee sting can cause a painful bump. The swelling can become quite large.
  • Lymph Nodes. Most common cause of a lump or mass felt under the skin. Commonly found in the neck or groin. Nodes have a boundary or edge and are movable. This is not the case for the swelling seen with insect bites. Lymph nodes become larger with infections.
  • Scalp Hematoma. The most common cause of a lump on the head is a scalp hematoma (goose egg). In a child under 2 years of age the injury may not have been seen.
  • Injuries. New lumps anywhere can be caused by an injury that wasn't observed. A bruise is often present with the swelling.
  • Callus. Broken bones heal with new bone formation. The medical term is callus. The callus feels like a bony knot that is larger than the bone itself. A callus is most commonly felt after a collarbone fracture.
  • Boils. A boil is a skin abscess. It causes a very painful red lump.

Lumps that are a Normal Part of the Body

  • Breast Bud. A small disc-shaped lump felt under the nipple. It indicates the onset of puberty in 7-12 year old girls.
  • External Occipital Protuberance. The bony lump felt at the base of the skull in back.
  • Mastoid Process. The bony lump felt behind each lower ear.
  • Xiphoid Process. A small hard lump felt at the lower end of the sternum (breastbone).

Common Objects Used to Guess the Size

  • Pea or pencil eraser: ¼ inch or 6 mm
  • Dime: ¾ inch or 1.8 cm
  • Quarter: 1 inch or 2.5 cm
  • Golf ball: 1 ½ inches or 3.8 cm
  • Tennis Ball: 2 ½ inches or 6.4 cm

When To Call

Call Doctor or Seek Care Now

  • Redness spreading from the lump with fever
  • Groin swelling and painful
  • Age less than 12 months and on scalp. Exception: normal bump in back at base of skull.
  • Your child looks or acts very sick
  • You think your child needs to be seen, and the problem is urgent

Contact Doctor Within 24 Hours

  • Redness spreading from the lump without fever
  • Boil suspected (painful, non-itchy, red lump)
  • Age 12 months or older and on scalp. Exception: normal bump in back at base of skull.
  • Can't move nearest joint normally (bend and straighten completely)
  • Swelling is painful and cause not known
  • You think your child needs to be seen, but the problem is not urgent

Contact Doctor During Office Hours

  • Large lump more than 1 inch (2.5 cm) and cause not known
  • Small lump lasts more than 7 days and cause not known
  • You have other questions or concerns

Self Care at Home

  • Small lump present 7 days or less and cause not known. Reason: probably due to insect bite not observed.
  • Breast bud - normal lump under the nipple
  • External occipital protuberance - normal lump on back of head
  • Mastoid process - normal lump behind each lower ear
  • Xiphoid process - normal lump at bottom of breastbone

Care Advice

Treatment for a Small Lump or Swelling

What You Should Know:

  • Most new swellings are due to insect bites. Mosquito bites account for 90% of them. Your child may not even know that he got bit.
  • Suspect an insect bite if there are bites on other parts of the body.
  • While most insect bites cause a small red bump, some are larger (like a hive).
  • This does not mean your child has an allergy or the bite is infected.
  • Here is some care advice that should help.

Cold Pack For Swelling:

  • Apply a cold pack or cold wet washcloth for 20 minutes.

Steroid Cream for Itching:

  • If the swelling is itchy, use 1% hydrocortisone cream (such as Cortaid). No prescription is needed.
  • Do this 3 times per day.

Allergy Medicine for Itching:

  • If itching becomes severe, give a dose of Benadryl.
  • No prescription is needed. Age limit: 1 and older.

What to Expect:

  • Most insect bites itch or hurt for 1 or 2 days.
  • The swelling usually peaks in 2 days, but may last a week.
  • If the swelling becomes larger or doesn't go away, it needs to be examined.

Call Your Doctor If:

  • Swelling becomes very painful
  • Fever occurs
  • Swelling becomes large (over 1 inch or 2.5 cm)
  • Swelling lasts over 7 days
  • You think your child needs to be seen
  • Your child becomes worse

Lumps that are a Normal Part of the Body

Breast Buds - Normal Lump Under the Nipple:

  • Breast buds are normal, small disc-shaped rubbery lumps felt under the nipple.
  • Age. They normally occur in 8-12 year old girls and are the first sign of puberty. Sometimes, they are even normal in 7 year olds.
  • One Side. They sometimes start just on one side. Don't worry about that. Within 2 or 3 months, a breast bud will also appear on the other side.
  • Importance. The entire breast develops entirely from the breast bud, taking 2 or 3 years to completion.
  • Symptoms. Breast buds normally can be somewhat tender.
  • Caution: Never squeeze or massage breast buds. Reason: Can cause a serious infection.
  • Risks. None. Breast buds have no risk of turning into cancer.
  • Follow-up. You can have your child's doctor check the breast bud during the next regular office visit.

External Occipital Protuberance - Normal Lump on Back of Head:

  • The lump you feel at the base of the skull in back is normal. It is a bony part of the skull that sticks out and feels hard.
  • If you feel carefully, you will find one on yourself or other children.
  • This is not caused by any injury.

Mastoid Process - Normal Lump Behind the Ear:

  • The mastoid process is a bony lump you can feel behind the lower ear.
  • Muscles that turn the neck attach to the mastoid process.
  • The process is larger in men because of larger neck muscles.
  • The mastoid is filled with air cells that connect to the inner ear.

Xiphoid Process - Normal Lump at Bottom of Breastbone:

  • The small hard lump at the lower end of the sternum (breastbone) is normal. It is called the xiphoid process. You can feel it.
  • It is more prominent in babies and slender children. Sometimes, it's more visible when breathing in.
  • If you feel carefully, you will find one on yourself or other children.
  • It's made of cartilage, but turns to bone in adults.

Call Your Doctor If:

  • You have other questions or concerns


Barton Schmitt MD, FAAP
Disclaimer: this health information is for educational purposes only. You, the reader, assume full responsibility for how you choose to use it.
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