Trichilemmal carcinomas
Trichilemmal carcinomas are rare, slow-growing malignant tumors that originate in the outer sheath of hair follicles, primarily affecting sun-exposed areas of the skin such as the face, arms, and scalp. These tumors are most commonly observed in individuals over 50 and show a similar incidence in both men and women. The precise cause of trichilemmal carcinomas remains unknown, although certain risk factors have been identified, including sun exposure, ionizing radiation, skin trauma, genetic predispositions, and immunosuppression.
Typically, a trichilemmal carcinoma appears as a small, tan, flesh-colored, or purplish spot, often resembling a wart and may contain a hair. Diagnosis is made through biopsy and histological examination by a pathologist. Surgical removal of the carcinoma is usually straightforward and performed as an outpatient procedure, with a low risk of complications. While recurrence at the same site can occur, metastasis is rare, and the overall prognosis for individuals after removal is excellent. No specific preventive measures are currently recommended due to the unknown nature of the carcinoma's cause.
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Subject Terms
Trichilemmal carcinomas
RELATED CONDITIONS: Trichilemmomas, Cowden syndrome
DEFINITION: Trichilemmal carcinomas are rare, slow-growing malignant tumors that start in the outer sheath of a hair root. They most often occur on skin that has been exposed to the sun, such as the face or arms.
Risk factors: There are specific risk factors for trichilemmal carcinomas, including exposure to the sun's ultraviolet radiation, exposure to ionizing radiation, skin trauma, genetic diseases, and a suppressed immune system.
Etiology and the disease process: The cause of trichilemmal carcinoma is not known. The carcinoma is slow-growing and does not cause pain.
Incidence: Trichilemmal carcinoma usually occurs in individuals over the age of fifty, with equal incidence in men and women. In 2024, only 136 cases were reported in medical literature.
Symptoms: A trichilemmal carcinoma appears as a small tan, flesh-colored, or purplish spot on the face, scalp, trunk, or extremities; usually, it is a single spot. The tumor may look like a wart and may have a hair in it. Less likely, the trichilemmal carcinoma may be on a part of the body that is not exposed to the sun, and it may appear as multiple spots. There are no other symptoms of a trichilemmal carcinoma.
Screening and diagnosis: Any spot on the skin that fits the description of a trichilemmal carcinoma should be looked at by a dermatologist. Trichilemmal carcinoma is diagnosed by biopsy and histological examination (when the tissue is viewed under a microscope by a pathologist). Trichilemmal carcinoma is most likely the malignant form of a noncancerous tumor called a trichilemmoma. A trichilemmal carcinoma is not the same as a malignant proliferating trichilemmal tumor (usually seen on the scalp or the back of the neck).
Treatment and therapy: The trichilemmal carcinoma spot is usually easily removed by a surgeon during an outpatient surgical procedure; the procedure is considered low risk, and additional therapy is not necessary. The spot may recur in the same location, and surgical removal should be repeated. A topical cream may also be prescribed by a doctor. Spread (metastasis) of a trichilemmal carcinoma is very unlikely. Should spread occur, radiation and immunotherapy may also be necessary.
Prognosis, prevention, and outcomes: The prognosis for individuals with a trichilemmal carcinoma removed is excellent. Since the underlying cause is not known, no recommended preventive strategies are recommended.
Bibliography
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Kazakov, Dmitry V. Cutaneous Adnexal Tumors. Philadelphia: Wolters, 2012.
Plaza, Jose A., and Victor G. Prieto. Neoplastic Lesions of the Skin. New York: Demos Medical, 2014.
Kemaloğlu, Cemal A., et al. "Malignant Proliferating Trichilemmal Tumor of the Scalp: Report of 4 Cases and a Short Review of the Literature." Case Reports in Plastic Surgery & Hand Surgery, vol. 9, no. 1, 2022, pp. 158-164, doi.org/10.1080/23320885.2022.2077208. Accessed 26 June 2024.
Ngan, Vanessa. “Trichilemmal Carcinoma.” DermNet, dermnetnz.org/topics/trichilemmal-carcinoma. Accessed 26 June 2024.
Rongioletti, Franco, Irina Margaritescu, and Bruce R. Smoller. Rare Malignant Skin Tumors. New York: Springer, 2015.
Rhoul, Chafik, et al. "A Rare Case Report of Trichilemmal Carcinoma." Cureus, vol. 14, no. 11, 2022, doi.org/10.7759/cureus.31261. Accessed 26 June 2024.
“Trichilemmal Carcinoma (Tricholemmal Carcinoma, Trichilemmomal Carcinoma).” Dermatology Advisor, 13 Mar. 2019, www.dermatologyadvisor.com/home/decision-support-in-medicine/dermatology/trichilemmal-carcinoma-tricholemmal-carcinoma-trichilemmomal-carcinoma. Accessed 26 June 2024.
Zhuang, Shi-Min, et al. "Survival Study and Clinicopathological Evaluation of Trichilemmal Carcinoma." Molecular and Clinical Oncology, vol. 1, no. 3, 2013, pp. 499-502, doi.org/10.3892/mco.2013.74. Accessed 26 June 2024.