What is pilomatrix carcinoma?
Pilomatrix carcinoma is a rare hair follicle tumor that occurs from a malignant transformation of a benign pilomatricoma. It wasn’t until 1980 when a review of several cases of biologically aggressive pilomatricoma confirmed the malignant transformation of these normally benign tumours. Since then there have only been about 90 reported cases of pilomatrix carcinoma. Some of these cases of pilomatrix carcinoma have arisen as a solitary lesion de novo. There is a high risk of recurrence after surgical excision and malignant features are often found in recurrent lesions.
Other names for pilomatrix carcinoma include pilomatricarcinoma and or pilomatrical carcinoma.
What are the clinical features of pilomatrix carcinoma?
Lesions of pilomatrix carcinoma are often found on the head and neck regions and vary in size from 1-10 cm. Unlike their benign counterpart where lesions are most often diagnosed in young children of both sex, the malignant variety is twice as likely to appear in white middle-aged men.
Lung metastases has been described and may occur years after the initial diagnosis.
How is pilomatrix carcinoma diagnosed?
Although pilomatrix carcinoma share some histological features with benign pilomatricoma, they may also have the following additional features:
- Frequent and abnormal mitosis
- Central or intratumoral necrosis
- Infiltration of skin and soft tissue
- Infiltration of blood and lymphatic system
The diagnosis of pilomatrix carcinoma is based on histological examination and the presence of the additional features from skin biopsy.
A MRI scan (magnetic resonance imaging) of the lesion may be required to determine the local spread of the tumour. Palpation of lymph nodes and a CT scan may also be performed to search for lung and liver metastases.
What is the treatment of pilomatrix carcinoma?
Due to the potential for metastasis to various sites, complete surgical excision with wide margins (2-3cm) is the recommended treatment. Mohs micrographic surgery may be used to ensure better margin control. Incomplete resections have led to local recurrences.
Adjuvant radiotherapy also has been used, but potential benefits are not well defined.