Trichoepithelioma - Symptoms, Diagnosis, and Treatment

What Is Trichoepithelioma?

Trichoepithelioma is an uncommon benign skin condition that originates from hair cells. These skin lesions are caused by the benign proliferation of cells of epithelial-mesenchymal origin. It usually affects the scalp, nose, forehead, and upper lip. In the autosomal dominant variant, it frequently manifests as multiple lesions. Still, the sporadic type manifests as a single flesh-colored papule or nodule measuring 2 to 8 mm.

Trichoepitheliomas are classified as follows:

• Solitary Trichoepithelioma: It is an uncommon benign hair follicle tumor with eyelid involvement. Solitary trichoepitheliomas are frequently mistaken for basal cell carcinoma. The differential between basal cell carcinoma and trichoepithelioma is clinically significant because basal cell carcinoma should be removed with a 3-4 mm margin of healthy tissue. Whereas a trichoepithelioma may require only minor resection.

• Multiple Familial Trichoepitheliomas: Trichoepithelioma (TE) is a benign follicular tumor that manifests as tiny, skin-colored papules on the face. Multiple familial trichoepitheliomas is a condition that affects more than one family member. It is an uncommon autosomal dominant (AD) skin disorder, and the malignant transition is unique.

• Desmoplastic Trichoepithelioma: Desmoplastic trichoepithelioma (DTE) is a rare benign appendageal skin cancer. Because of its distinct clinical and histological features, it is a different form of trichoepithelioma. It usually manifests as a single lesion, although multiple lesions have also been found in rare situations. Most desmoplastic trichoepithelioma (DTE) manifests as a white to yellowish annular nodule or papule with a central depression. Female patients are the most commonly affected; the most common place is on the face or cheeks.

How Does It Occur?

Due to its autosomal dominant nature, all genders acquire the gene for trichoepithelioma; however, females develop it more due to high expressivity than men. The gene for familial trichoepithelioma development encodes a tumor suppressor and is linked to the short arm of chromosome 9. Furthermore, because this illness is most frequent in young to middle-aged women, it may result in psychological distress.

In 1996, scientists discovered a mutation in this tumor suppressor encoding gene on band 9q21 in numerous familial trichoepitheliomas. Thus, trichoepithelioma has a rare risk of malignancy and shares histological similarities with basal cell carcinoma, and needs careful examination and management.

What Are the Causes of Its Occurrence?

Various genetic mutations have been linked to the incidence of trichoepithelioma. They are as follows:

1. Genetic mutation is located on chromosome 9p21 (16).

2. Cylindromatosis tumor suppressor gene (CYLD) mutation discovered on chromosome 16q12-q13.

3. A mutation on chromosome 9q22.3 has been related to solitary trichoepithelioma.

What Are the Symptoms of Trichoepithelioma?

• Trichoepithelioma lesions are characterized by several skin-colored, pinkish-blue firm, spherical, transparent, and well-defined nodules or papules.

• They are most commonly found on the face, around the nasolabial folds, the forehead, the nose, and the eyelids.

• They are generally symmetrical on the face, and the scalp, neck, and upper torso are occasionally affected.

• The lesions are typically 2 to 5 mm in diameter; however, they can grow to be up to 5 cm.

• The frequency of trichoepithelioma lesions may also steadily rise with time.

• The lesions may have an umbilicated or somewhat depressed core.

• Dilated blood vessels might appear on the surface of larger lesions.

• As trichoepithelioma lesions lack ulceration and do not cause itching, and are considered harmless.

• They can, however, develop into malignant neoplasms such as basal cell carcinoma (BCC).

What Are the Systemic Complications of Trichoepithelioma?

The following systemic anomalies have been described as associated with trichoepithelioma:

• Epilepsy.

• Clefts in the hard and soft palates.

• Cysts in the jaws.

• Dementia.

• Bradykinesia.

• Deafness.

• Contracture of Dupuytren-hand deformity.

• Disruption of urination.

How Is Trichoepithelioma Diagnosed?

1) Cytology -

• Cytology of fine needle aspiration reveals a highly cellular aspirate with a frond pattern of basaloid cells.

• The epithelial component consists of nests and adenoid patterns of unified basaloid cells with scanty cytoplasm and a darkly colored nucleus.

• Spindle-shaped cells in myxoid tissue make up the mesenchymal component and are seen navigating the epithelial component as well.

• The presence of acellular eosinophilic cells, which represent abrupt proliferation and differentiation, aids in diagnosis.

2) Histopathology-

Tumors of the hair follicles are classified based on their predominant lines of differentiation. Lesions with a high degree of differentiation toward hair structures are given the histological designation "solitary trichoepithelioma." The more mature end of the spectrum is represented by multiple trichoepitheliomas.

Microscopy of hematoxylin and eosin stains reveals:

• Subcutaneous tumor with normal overlying epidermis.

• Dome-shaped epithelial tumors within the dermis can be seen.

• Islands of unified basaloid cells with scant cytoplasm and a darkly smeared nucleus arranged in nests.

• Adenoid pattern with epithelial islands.

• The presence of pleomorphic giant cells does not indicate "malignant transformation" in a tumor with a low proliferative index.

• Trichoepithelioma may manifest as a pigmented lesion due to increased melanocyte activity or pigment retention in basal keratinocytes.

3) Immunohistochemistry -

Immunohistochemistry is commonly used to differentiate trichoepithelioma from basal cell carcinoma. The markers used are as follows:

What Is the Difference Between Trichoepithelioma and Basal Cell Carcinoma?

Trichoepithelioma histologically resembles basal cell carcinoma, and while benign, there is a rare possibility of malignant change. Immunohistochemical staining can occasionally help distinguish trichoepithelioma from basal cell cancer. Some of the features that distinguish them are listed below:

What Is the Treatment of Trichoepithelioma?

Even though trichoepithelioma is symptomless, affected patients seek treatment primarily for cosmetic reasons because the lesions are usually disabling, leading to social isolation. There are currently no preventive measures available. The primary treatment method is excisional surgery.

The various other treatment modalities are as follows:

1. Surgical removal.

2. Electrodesiccation.

3. Skin transplantation.

4. Electrosurgery and cryosurgery.

5. Laser therapy.

6. Dermabrasion and curettage

Which Pharmacotherapy Is Used to Treat Trichoepitheliomas?

Since these lesions may regress and become less visible over time, as well as the complications of non-pharmacological measures, some experts recommend a wait-and-see approach. Due to the limitations of non-pharmacological therapies, pharmacotherapy for trichoepitheliomas management used are as follows:

• 13-cis-Retinoic acid.

• Imiquimod cream in combination with one percent Tretinoin gel.

• Aspirin in combination with Adalimumab.

• Topical five percent Imiquimod cream.

What Are the Drawbacks of the Various Treatments?

• Trichoepitheliomas treated with the erbium: Yag and CO2 lasers had less scarring and recurrence after two years than conventional treatments. In one Brazilian study, trichoepitheliomas treated with Imiquimod cream showed an 80 percent clearing rate.

• Dermabrasion and curettage, on the other hand, have been reported to cause the lesion to reoccur. The recurrence of skin lesions is a possible side effect of all non-pharmacological treatments. Pain requiring a local anesthetic injection, bleeding, scarring, and secondary skin cancer are all possibilities. Aside from these drawbacks, these approaches are time-consuming, costly, and inconvenient for patients.

• The use of ineffective techniques may result in partial therapy and illness recurrence, while overtreatment may raise the risk of aesthetic and functional damage. As a result, accurate treatment selection based on the depth of the lesions is critical to avoid over-treatment and unwanted problems. Thus, it should be noted that the depth of the skin lesions is critical in their therapy, and some individuals may require skin grafting after the lesions are excised.

Conclusion

Trichoepithelioma has been reported to have a rare incidence of malignant change. Furthermore, because this condition is most common in young to old women, it may cause social and psychological problems. It has been suggested that doctors should carefully check patients and be especially wary of any fast development or ulceration in pre-existing lesions since these are likely signs of malignant transformation. As a result, a thorough diagnosis and early care of this uncommon disease are required to examine the effectiveness and failure of various treatment modalities.