Pilomatrixoma

What causes a pilomatrixoma?

The exact underlying cause of pilomatrixoma is not well understood. Changes (mutations) in the CTNNB1 gene are found in at least 75% of isolated (without other signs and symptoms) pilomatrixomas. These mutations are somatic, which means they are not inherited and are only present in the tumor cells. The CTNNB1 gene encodes a protein that is needed to regulate cell growth and attachment. When the gene is not working properly, it can result in abnormal cell growth.

Rarely, pilomatrixomas occur in people with certain genetic syndromes such as Gardner syndrome, myotonic dystrophy, and Rubinstein-Taybi syndrome. In these cases, affected people usually have other characteristic features of the associated condition.

Last updated on 05-01-20

Does injury cause pilomatrixoma to develop?

In general, pilomatrixomas are not believed to be caused by previous injury to the area. Two articles in the medical literature describe cases of pilomatrixoma that followed instances of injury to the area; however, the authors do not state this as a direct cause of the tumor. Another article states that injury to a pilomatrixoma may influence it to form a particular subtype called anetodermic pilomatrixoma, but no cause-effect connection has been proven.

Last updated on 05-01-20

How is a pilomatrixoma diagnosed?

A diagnosis of pilomatrixoma is usually suspected on physical examination. Specialized tests may be ordered to confirm the diagnosis and rule out other conditions that cause similar features. These tests may include an ultrasound, an X-ray, and/or a small biopsy of the tumor.

Last updated on 05-01-20

Is a pilomatrixoma inherited?

Most isolated (without other signs and symptoms) pilomatrixomas are not inherited. However, more than one family member can rarely be affected, which suggests there may be a hereditary component in some cases.

Rarely, pilomatrixomas occur in people with certain genetic syndromes such as Gardner syndrome, myotonic dystrophy, and Rubinstein-Taybi syndrome. In these cases, affected people usually have other characteristic signs and symptoms of the associated condition. All three of these conditions are inherited in an autosomal dominant manner. In some cases, an affected person inherits the mutation from an affected parent. Other cases may result from new (de novo) mutations in the gene. These cases occur in people with no history of the disorder in their family.

Last updated on 05-01-20

Is it normal for multiple pilomatrixomas to develop?

Approximately 3.5% of individuals with pilomatrixomas develop multiple pilomatrixomas over time. In a small number of these cases, multiple pilomatrixomas have been associated with a genetic condition called myotonic dystrophy, or rarely other genetic conditions. Because of this potential association, it has been suggested that individuals with multiple pilomatrixomas undergo a careful physical examination and continued follow-up.

Last updated on 05-01-20

Do pilomatrixomas continue to develop over an individual's lifetime?

Most pilomatrixomas develop before the age of 20. However, there is small chance of developing these tumors later in life, particularly after age 50.

Last updated on 05-01-20

What is the long-term outlook for people with a pilomatrixoma?

The long-term outlook (prognosis) for people with an isolated (without other signs and symptoms) pilomatrixoma is usually good. Most people do not experience any serious complications, although pilomatrixomas can become cancerous (known as a pilomatrix carcinoma) in rare cases. When surgically removed, pilomatrixomas typically do not grow back (recur), unless the excision was incomplete.

Rarely, pilomatrixomas occur in people with certain genetic syndromes such as Gardner syndrome, myotonic dystrophy, and Rubinstein-Taybi syndrome. In these cases, the prognosis varies based on the condition and its associated symptoms.

Last updated on 05-01-20

How might a pilomatrixoma be treated?

Pilomatrixomas are usually surgically removed (excised). In most cases, the tumors do not grow back (recur) after surgery, unless the removal was incomplete.

Last updated on 05-01-20


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