Pilomatrixomas are rare, slow-growing tumors that derive from hair follicle cells, which are ectodermal in origin. They develop in the lower dermis, present as irregularly shaped, firm growths that are tethered to the overlying skin but are not, however, attached to the underlying tissue. They often cause a blue or red discoloration on the skin but are otherwise non-tender [1]. Moreover, pilomatrixomas have the ability to calcify or ossify.

They most frequently occur within the first decade of life and affect females more than males [2]. Furthermore, they are usually found in the head and neck region, but have also been reported in the upper extremities. Typically, pilomatrixomas are solitary, yet multiple growths can occur simultaneously. The occurrence of the latter may be linked to various conditions, exemplified by sarcoidosis, Gardner syndrome, and myotonic dystrophy [3].

An even rarer type of tumor is the malignant form of pilomatrixomas, that is, pilomatrix carcinoma. These may present in a similar manner to pilomatrixomas, but are distinguished by their rapid growth, and involvement of the hematologic and lymphatic systems [4]. They have a tendency to recur and sometimes metastasize.

The diagnosis of pilomatrixoma is often missed, with the correct identification of the mass being less than 30% pre-operatively [5]. The reason for the high diagnostic inaccuracy may be a combination of the rarity of the tumor, its similarity to other superficial masses such as dermoid cysts, lipomas, foreign bodies and branchial cleft cysts, and atypical features such as an uncommon location [6].

The diagnosis of pilomatrixomas can be made based on clinical findings alone. The tent sign can be elicited and allows visualization of the irregularity of the mass. There is no development of lymphadenopathy. The modal location of tumors is the periorbital area, and a minority of cases are preceded by a history of trauma.

Histologically, pilomatrixomas are well circumscribed and surrounded by connective tissue. They consist of groups of metrical cells with cystic changes and central degeneration caused by ghost cells which lack a nucleus and are not exclusively found in pilomatrixomas [7]. Inflammation may be present in the surrounding tissue. Calcification occurs in the majority of tumors, whilst other changes that can occur include a local build-up of keratin, and foreign body granulomas [6].

Imaging studies are not routinely required. If X-rays are carried out, there may be visible calcifications. Pilomatrixomas are depicted on computerized tomography (CT) scans as soft tissue masses that may also contain calcifications. Magnetic resonance imaging (MRI) reveals ring-enhancing lesions, while ultrasonography may reveal peripherally hyperechoic masses with acoustic shadowing visible in the subcutaneous tissue [8].

Fine needle aspiration cytology (FNAC) remains the most accurate diagnostic test, although it also has a high margin of error [7]. On FNAC, basaloid and ghost cells are indicative of pilomatrixomas [9].

The primary treatment for pilomatrixoma is surgical excision. This involves removing the tumor along with a small margin of surrounding healthy tissue to ensure complete removal and prevent recurrence. The procedure is usually straightforward and can often be performed under local anesthesia. In rare cases where the tumor is large or located in a cosmetically sensitive area, more complex surgical techniques may be required.

The prognosis for individuals with pilomatrixoma is excellent. These tumors are benign and do not metastasize, meaning they do not spread to other parts of the body. Recurrence after surgical removal is uncommon, especially when the excision is complete. In rare instances, multiple pilomatrixomas may occur, but this does not typically affect the overall prognosis.

The exact cause of pilomatrixoma is not well understood, but it is believed to arise from abnormal development of hair follicle matrix cells. Genetic factors may play a role, as some cases have been associated with mutations in the CTNNB1 gene, which is involved in cell signaling and regulation. However, most cases occur sporadically without a clear genetic link.

Pilomatrixoma is relatively uncommon, accounting for less than 1% of all skin tumors. It is most frequently diagnosed in children and young adults, with a peak incidence between the ages of 5 and 15. There is a slight female predominance, and the condition is more common in Caucasians. While pilomatrixomas can occur at any age, they are rare in older adults.

The pathophysiology of pilomatrixoma involves the abnormal proliferation of hair follicle matrix cells, which are responsible for producing hair. These cells undergo a process of keratinization, leading to the formation of shadow cells—anucleated cells that are a hallmark of the tumor. Over time, calcium deposits may accumulate within the tumor, contributing to its firm texture.

There are no specific measures to prevent pilomatrixoma, as the exact cause is not well understood. However, early detection and treatment can prevent potential complications such as infection or cosmetic concerns. Regular skin examinations and awareness of any new or changing skin lesions can aid in early identification.

Pilomatrixoma is a benign skin tumor arising from hair follicle matrix cells, most commonly affecting children and young adults. It presents as a firm, painless nodule beneath the skin, often on the face or neck. Diagnosis is confirmed through biopsy, and treatment involves surgical excision. The prognosis is excellent, with a low risk of recurrence. While the exact cause is unclear, genetic factors may play a role in some cases.

If you or your child has been diagnosed with pilomatrixoma, it's important to know that this is a benign condition with an excellent prognosis. The tumor is not cancerous and does not spread to other parts of the body. Treatment typically involves a simple surgical procedure to remove the lump, which is usually successful in preventing recurrence. If you notice any new or unusual lumps on the skin, it's a good idea to have them evaluated by a healthcare professional to ensure proper diagnosis and management.

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