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What is a Hamartoma?

What Does it Mean if I Have a Hamartoma?


Updated April 29, 2014

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

Hamartomas are fairly common tumors, but if your doctor tells you that you have one, you may be terrified. Most people have never heard about these benign tumors, and they can look a lot like cancer on imaging studies. What should you know and what questions should you ask if you’ve been told you have a hamartoma?

What is a Hamartoma?

A hamartoma is a benign (non-cancerous) tumor that is made up of “normal” tissues that are found in the region in which they grow. For example, a lung (pulmonary) hamartoma is a growth of non-cancerous tissues including fat, connective tissue, and cartilage that is found in the regions of the lungs.

The difference between hamartomas and normal tissue is that hamartomas grow in a disorganized mass. Most hamartomas grow slowly, at a rate similar to normal tissues. They are more common in men than in women. While some are hereditary, nobody knows for certain what causes many of these growths to occur.


Hamartomas may not cause any symptoms, or they may cause discomfort due to pressure on nearby organs and tissues. These symptoms will depend upon the location of the hamartoma.

Where Do Hamartomas Occur?

Hamartomas can occur almost anywhere in the body. Some of the more common areas include:
  • Lungs - Pulmonary (lung) hamartomas are the most common type of benign lung tumors. They are usually found accidentally when a chest x-ray or chest CT scan is done for some other reason. If they occur near an airway, they may cause an obstruction resulting in pneumonia and bronchiectasis.

  • Skin – especially on the face, lips and neck

  • Heart – As the most common heart tumor in children, hamartomas can cause symptoms of heart failure.

  • Hypothalamus – Since the hypothalamus is in an enclosed space in the brain, symptoms due to pressure on nearby structures are fairly common. Some of these include seizures, personality changes, and early onset of puberty in children.

  • Kidneys

  • Spleen – Hamartomas in the spleen may cause abdominal pain.

Lung (Pulmonary) Hamartomas

As noted above, lung (pulmonary) hamartomas are the most common benign tumors found in the lungs, and are often discovered accidentally when chest imaging is done for some other reason. With the increased use of CT screening to look for lung cancer in people at risk, it’s likely that more people will be diagnosed with hamartomas in the future.

Hamartomas can be difficult to distinguish from cancers, but do have some characteristics that set them apart. A description of “popcorn calcification” -- meaning images that look like popcorn on a CT scan -- is almost diagnostic. Calcification (deposits of calcium that appear white on x-ray studies) are common. Cavitation, a central area of tissue breakdown seen on x-rays, is uncommon. Most of these tumors are less than 4 cm (2 inches) in diameter.

Can Hamartomas Spread or Cause Damage Like Cancers Do?

Unlike malignant (cancerous) tumors, hamartomas do not usually spread to other regions of the body. That said, depending on their location, they can cause damage by placing pressure on nearby structures.

It’s also important to note that people with Cowden’s disease (a syndrome in which people have multiple hamartomas) are more likely to develop cancers, especially of the breast and thyroid.

What Causes Hamartomas?

The cause of hamartomas is unknown, although some occur as part of a hereditary syndrome. Cowden’s disease is one of these. Cowden’s disease is most often caused by an autosomal dominant genetic mutation. In addition to multiple hamartomas, people with this syndrome often develop cancers of the breast, thyroid and uterus.


Treatment options will depend upon the location of the tumor and whether or not it is causing symptoms. If hamartomas are not causing symptoms, your doctor may recommend that they be left alone and observed over time.

Questions to Ask Your Doctor

  • Will my hamartoma need to be removed (i.e., will it cause any problems if left in place)?
  • What symptoms might I expect if it grows?
  • What type of procedure do you recommend to remove my tumor?
  • Will I need any special follow-up in the future?
  • Is there a possibility that I have a genetic mutation that caused my tumor, and if so, is there any special follow-up I should have, such as more frequent mammograms?


De Cicco, C. et al. Imaging of Lung Hamartomas by Multidetector Computed Tomography and Positron Emission Tomography. Annals of Thoracic Surgery. 2008. 86:1769-1772.

Edey, A., and D. Hansell. Incidentally detected small pulmonary nodules on CT. Clinical Radiology. 2009. 64(9):872-84.

Farooq, A. et al. Cowden syndrome. Cancer Treatment Reviews. 2010. 36(8):577-83.

Saqi, A. et al. Incidence and cytological features of pulmonary hamartomas indeterminate on CT scan. Cytopathology. 2008. 19(3):185-191.

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