What is trichilemmal carcinoma?
Trichilemmal carcinoma is a rare hair follicle tumour that is thought to occur from a malignant transformation of a benign trichilemmoma. The tumour develops from the outer root sheath of the hair follicle. It is most often found on areas that are exposed to the sun, particularly on the face and ears of elderly women. Trichilemmal carcinoma is considered to have low metastatic potential, meaning it is a low-grade carcinoma that rarely spreads to other parts of the body.
What are the clinical features of trichilemmal carcinoma?
Lesions of trichilemmal carcinoma are generally found on the scalp, forehead or neck. It is a tan or flesh-coloured spot that may resemble a wart. It most commonly occurs in women over 40 years of age.
Even though histological features suggest medium to high grade malignancy, trichilemmal carcinoma usually follow a relatively benign clinical course with no apparent symptoms that cause the patient concern.
How is trichilemmal carcinoma diagnosed?
Because trichilemmal carcinoma is rare and its presentation is similar to other skin tumours, diagnosis is based on the presence of certain features on histological examination of a skin biopsy.
Trichilemmal carcinoma should be differentiated from other skin tumours, such as squamous cell carcinoma and basal cell carcinoma, which are more common.
What is the treatment of trichilemmal carcinoma?
Complete surgical excision with wide margins (2-3cm) is the recommended treatment for trichilemmal carcinoma. Mohs micrographic surgery may be used to ensure better margin control. Although recurrent trichilemmal carcinoma is uncommon, there have been rare reports where incomplete resections may have led to local recurrences and metastatic spread.
Recurrent tumour must be surgically removed. Currently there is no established treatment for metastatic trichilemmal carcinoma but chemotherapy similar to regimens used for squamous cell carcinoma have been used.