Pilomatricomas are noncancerous skin tumors originating from hair follicle cells. They are also known as pilomatrixomas or calcifying epitheliomas of Malherbe. They are an uncommon type of skin lesion, often found beneath the skin’s surface. These tumors arise from the hair matrix, the part of the hair follicle responsible for hair growth.
Characteristics of Pilomatricomas
Pilomatricomas present as firm, solitary nodules under the skin. They can range in color from skin-colored to bluish-red or purplish. These nodules feel hard and bony due to calcification, and stretching the skin over them can reveal an angulated shape, known as the “tent sign.” Most pilomatricomas measure between 0.5 to 3.0 centimeters, though some can be larger.
These tumors are most frequently found on the head and neck, but can also appear on the upper extremities, trunk, or lower extremities. Pilomatricomas can occur at any age, but are most common in children and young adults. They grow slowly and are often asymptomatic, meaning they do not cause pain or other symptoms, though tenderness can occur with inflammation.
Identifying Pilomatricomas
Diagnosis often begins with a clinical examination by a healthcare professional, noting the nodule’s characteristic hard, mobile feel and appearance. Imaging, such as ultrasound, may be used to assess the lesion and help distinguish it from other conditions like epidermal inclusion cysts.
A definitive diagnosis requires a biopsy and histopathological examination. Under the microscope, pilomatricomas show distinct features, including basaloid cells and ghost cells, which are characteristic of these tumors. The presence of calcium deposits is also a common finding.
Management of Pilomatricomas
Surgical excision is the primary treatment for pilomatricomas. This approach is recommended to confirm diagnosis, prevent growth, address cosmetic concerns, and alleviate discomfort. The procedure involves local anesthesia and a small incision to remove the entire tumor with a margin of normal tissue.
For younger patients, minimally invasive techniques like curettage or punch excision may be considered to reduce scarring, especially in cosmetically sensitive areas. Complete removal of the tumor is important to minimize recurrence. Non-surgical treatments are generally not effective, as these tumors do not spontaneously regress.
Long-Term Outlook
The prognosis for individuals with pilomatricomas is generally excellent, given their benign nature. While most cases are isolated, multiple pilomatricomas can rarely occur and have been associated with certain genetic disorders. Recurrence after surgical removal is uncommon, especially with complete excision.
However, incomplete removal can lead to local recurrence. Rarely, a benign pilomatricoma can undergo malignant transformation into a pilomatrix carcinoma. This malignant variant is rarer, with a tendency for local aggressiveness and potential for metastasis. Pilomatrix carcinoma affects middle-aged or older individuals, in contrast to the benign form.