Hamartoma

A hamartoma is a benign (non-cancerous) growth made up of an abnormal mixture of cells and tissues that are normally found in the area of the body where the growth occurs. Unlike neoplasms, which arise from a single cell that starts growing uncontrollably, a hamartoma consists of disorganized but mature tissue elements that belong in that particular tissue or organ. Think of it as a small patch of tissue that didn’t develop quite right but isn’t harmful.

Where are hamartomas commonly found?

Hamartomas can occur in many body parts, most commonly in the lungs, liver, kidneys, skin, and brain. For example, a hamartoma might consist of a mixture of cartilage, fat, and connective tissue in the lungs. In the skin, it might appear as a birthmark or a small lump.

What is the difference between a hamartoma and a tumour?

A hamartoma is a type of tumour, but it is always benign. Unlike most tumours, which can be benign or malignant, a hamartoma is made up of disorganized but mature tissue that is native to the organ where it is found. While a hamartoma does not have the potential to invade nearby tissues or spread to other parts of the body, it differs from malignant tumours in that it is simply a disorganized collection of normal tissue rather than a mass of cells growing uncontrollably.

Are hamartomas benign or malignant?

Hamartomas are always benign, meaning they are not cancerous and do not spread to other body parts. However, depending on their location, some hamartomas can grow large enough to cause symptoms by pressing on nearby structures. They do not have the invasive or metastatic potential seen in malignant tumours.

What causes a hamartoma?

The exact cause of hamartomas is not fully understood. They are generally thought to arise from a developmental error where the cells that make up the tissue fail to organize correctly during growth. Some hamartomas are associated with genetic conditions, such as Cowden syndrome, where multiple hamartomas can occur in different body parts. However, most hamartomas are sporadic, meaning they occur by chance and are not inherited.

What types of tissue are commonly found in a hamartoma?

The types of tissue found in a hamartoma depend on the part of the body where it develops. For example:

• Lung hamartomas often contain cartilage, connective tissue, fat, and sometimes bone.
• Skin hamartomas might be an overgrowth of hair follicles, sebaceous (oil) glands, or blood vessels.
• Brain hamartomas can contain a mix of glial cells (supportive cells in the brain), neurons, and blood vessels.

Each hamartoma is unique in its composition, but the tissues present are always native to the organ where the hamartoma is located.