Pilomatricoma: Understanding This Rare Skin Tumor

A pilomatricoma, also known as a pilomatrixoma, is generally a benign tumor that originates in hair follicles. Although typically noncancerous, there have been rare instances where it transforms into a malignant form. This growth often appears as a hard lump beneath the skin, most commonly located on the head and neck. It primarily affects children and young adults, particularly those under 20 years of age.

While there have been fewer than 130 documented cases of malignant pilomatricomas in medical literature, the majority of these tumors remain harmless.

Pilomatricomas can vary in size from approximately 0.25 inches to 2 inches and tend to develop slowly. They are usually painless and may appear as single or multiple lumps. Other recognizable symptoms include:

• Discoloration of the skin, appearing bluish-red
• The "tent sign," where the skin shows angles and facets when stretched
• The "teeter-totter sign," where pressing on one side of the lump causes the opposite end to protrude

Pilomatricomas emerge from the hair matrix cells located within hair follicles. These cells are responsible for producing hair fibers and can exhibit abnormal growth patterns in the case of pilomatricoma. Researchers believe that a mutation in the CTNNB gene, responsible for cellular adhesion, may contribute to the irregular cell reproduction seen in these tumors. Notably, this mutation is acquired and is not hereditary, appearing in both benign and malignant variants.

Pilomatricomas predominantly affect children and young individuals. Approximately 40% of cases are diagnosed before the age of 10, while about 60% manifest before the age of 20. Additionally, females are statistically more likely (about 50% higher risk) to develop pilomatricomas compared to males. Conversely, malignant forms are more frequently observed in middle-aged white males.

Due to their similarity to other benign skin growths, such as dermoid or epidermoid cysts, pilomatricomas can sometimes be misidentified. To accurately diagnose a pilomatricoma, a skin biopsy is often performed. This procedure involves excising a portion or the entirety of the growth for microscopic examination, allowing for confirmation and assessment of any potential malignancy.

While pilomatricomas generally do not result in medical complications, they do not resolve independently and may gradually increase in size. Thus, many individuals opt for surgical removal. The typical treatment involves surgical excision, which is a relatively straightforward procedure performed under local anesthesia. Following the excision, the removed tissue may be tested to ensure that it is noncancerous.

Although extremely rare, there are instances where pilomatricomas may become cancerous. Since 1980, only about 90 such cases have been reported. Should a biopsy indicate malignancy, the doctor will typically excise the tumor along with some surrounding tissue to minimize the risk of recurrence.

In summary, pilomatricomas are uncommon yet mostly benign skin tumors that frequently affect the pediatric and young adult populations. These growths typically do not cause significant health issues, but medical professionals often recommend surgical removal to prevent any potential enlargement over time.