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Trichilemmoma - Causes, Clinical Features, and Treatment

Published on Aug 26, 2022 and last reviewed on Feb 14, 2023   -  4 min read


Trichilemmoma is a benign adnexal tumor of the skin. This benign neoplasm develops from the outer sheath of the hair follicle. It is also called trichilemmoma.


Trichilemmoma is a benign cutaneous tumor that develops from pilosebaceous follicular epithelium or the outer sheath of the follicle. Headington and French first described it in 1962. Trichilemmoma is one of the many skin adnexal tumors (tumors associated with structures responsible for sensation, lubrication, heat loss, and lubrication of the skin) that comprises benign and malignant cutaneous tumors. Most skin adnexal tumors (SAT) are non-serious and can be treated by surgical excision. Skin adnexal tumors are uncommon tumors and mostly not harmful. Trichilemmoma is classified under benign adnexal tumors that develop due to the hamartomatous proliferation (abnormal proliferation of cells and tissues found in the organ) of the hair follicle. This tumor has cells from just below the basement membrane at the level of sebaceous glands.

What Is Trichilemmoma?

Trichilemmoma is a solid tumor that develops into a lobular form or plate-like, abundant with glycogenated clear cells, and occasionally exhibits keratinization at the center of the tumor. Trichilemmoma can occur at any age and grow up to the size of 5 cm. However, it is mostly in women and Caucasians. Mostly it is located on the face, nose, eyelids, lips, and oral cavity. Trichilemmoma usually develops as a solitary tumor.

Multiple trichilemmomas can be found associated with Cowden's syndrome. This syndrome is an inherited autosomal dominant disorder. Sometimes, trichilemmoma develops alongside other cutaneous lesions such as sebaceous adenoma and sebaceous nevus.

What Is the Cause for Trichilemmoma?

The exact cause of trichilemmoma remains unknown. However, several studies and observations have been conducted. Therefore, scholars provide a theory-based etiology.

  • Trichilemmoma is observed to be associated with a viral infection that is caused due to human papillomavirus (HPV). However, there is no evidence for such a speculation. Polymerase chain reaction (PCR) identified several virus subtypes from the tissue specimen. The fundamental cause is yet to be established. The studies are, however, limited due to their rare occurrence.

  • Around 80 cases of trichilemmoma have been reported in the past 30 years.

  • This benign tumor is found to be solitary in most cases. Multiple lesions are found to be associated with Cowden's syndrome. This syndrome is an inherited autosomal dominant trait characterized by hamartomatous growths predisposed to malignancy. This syndrome causes mucocutaneous, gastrointestinal, breast, and thyroid abnormalities along with other cancers like squamous cell carcinoma, basal cell carcinoma, liposarcoma, renal cell carcinoma, and hepatocellular carcinoma. The hamartomas' cause is attributed to the PTEN (phosphatase and tensin) mutation.

What Are the Clinical Features of Trichilemmoma?

Trichilemmoma can appear anywhere on the body. These lesions are predominant on the head, neck, oral cavity, and thyroid gland. The lesion appears as a single papule or plaque-like on the skin's surface. They are asymptomatic and slow-growing, bearing skin color. Lesions can grow up to 5 cm. When they grow in size, lesions become thickened on the surface. They also form small plaque-like lesions resembling warts or a cutaneous horn. They are often present on the face and neck. Trichilemmoma can be single or multiple.

When it occurs on the face, the patient is often skeptical. The patient might not be worried about the discomfort of its presence but are worried about scar formation. Some patients need assurance that it is not cancer. If the lesions are multiple, doctor efforts are directed towards identifying the presence of Cowden's syndrome. Multiple trichilemmomas may also indicate a malignancy, which should be diagnosed thoroughly. Lesions on the eyes are primarily fleshy, solitary, and painless, found on upper and lower eyelids. There is no clinical feature that can diagnose trichilemmoma. Therefore, the histopathological study is the only investigative technique to diagnose trichilemmoma.

What Does the Specimen Show Under Microscope?

The histological features of trichilemmoma are as follows:

  1. Hyperkeratosis-thickening of the outer layer of the skin that is made of keratin.

  2. Acanthosis-discoloration of body folds and creases (armpits, groin, neck).

  3. Cutaneous horn-a growth that appears on the skin typically made up of keratin.

  4. Lobular epidermal growth projects downwards into the dermis.

  5. Glycogenated clear cells- cells that are rich in glycogen.

  6. Some cells are vacuolated and exhibit keratohyalin granules.

  7. Cells are periodic acid-Schiff positive (PAS).

  8. Cells at the periphery are basophilic.

  9. Cells at the center show clear cytoplasm.

  10. Foci of epidermal keratinization with the formation of squamous eddies.

  11. Eosinophilic hyaline basement membrane surrounds the tumor that is positive for periodic acid Schiff.

What Is the Treatment for Trichilemmoma?

Trichilemmoma is a benign tumor that requires no treatment. However, lesions are often removed for aesthetic purposes or if the lesion has occurred in any sensitive areas that cause discomfort. The surgery aims to establish an accurate diagnosis and ensure that the malignant tumor is not left unidentified. Treatment options include:

  • Curettage and Electrodesiccation: This type of skin cancer treatment removes abnormal skin growths.

  • Surgical Excision: Removal of the part or entire lesion under anesthesia for investigation or as a part of treatment.

  • Mohs Micrographic Surgery is a precise surgical technique to treat skin cancers.

  • Carbon Dioxide Laser Therapy: It is an ablative laser therapy that uses carbon dioxide gas to precisely reach the top layers of skin to treat various skin conditions causing minimal damage and discomfort.

The most effective treatment option proved till today is carbon dioxide laser therapy for tissue ablation. This therapy is used in many cutaneous lesions. Carbon-dioxide laser therapy is quick, precise, and has minimal morbidity. Since it has excellent esthetic results, it is used in many epidermal lesions. In addition, this therapy helps treat multiple trichilemmomas (Cowden's syndrome).


Cutaneous adnexal tumors are very common among the Indian population. Though benign skin tumors are common compared to malignant skin lesions, trichilemmoma is a benign cutaneous tumor that does not have any treatment. Treatment is necessary when it is disturbing the esthetics of an individual and when it causes any discomfort. It rarely undergoes a malignant transformation. This benign lesion can occur anywhere on the body. It is more common in the elderly age group.

Last reviewed at:
14 Feb 2023  -  4 min read




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