Trichoepithelioma is a benign tumor that can be solitary or multifocal (1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16). Solitary trichoepithelioma is generally unassociated with genetic or systemic abnormalities. It can occur anywhere on the body, but has a predilection for the face and eyelids. The multifocal variant (Brooke’s tumor) is transmitted by an autosomal-dominant mode of inheritance. Trichoepithelioma accounts for about 1% to 2% of biopsied sweat gland or hair follicle tumors (10).

Solitary trichoepithelioma generally has its onset in early adulthood as a skin-colored, dome-shaped papule that may remain stable or gradually enlarge and become crusty (1,2). Larger trichoepithelioma may have telangiectatic blood vessels and resemble basal cell carcinoma. However, unlike basal cell carcinoma, it is relatively stationary and rarely ulcerates (1,2,3,4,5,6,7,8,9,10,11,12,13,14,15).

The autosomal-dominant multiple trichoepithelioma (also called Brooke’s tumor and adenoid cystic epithelioma) has its onset in the second decade of life and the lesions slowly increase in number (8). It begins as multiple, skin-colored, firm papules usually between 2 and 8 mm in diameter, located mainly in the nasolabial folds, facial skin, and sometimes the eyelids (7). Ulceration and transformation into basal cell carcinoma are rare. The clinical appearance may be similar to nevoid basal cell carcinoma syndrome, facial angiofibromas of tuberous sclerosis, sarcoidosis, or syringoma. Multiple trichoepitheliomas have also been observed in association with multiple cylindromas, a condition that also has autosomal-dominant inheritance (7,12,13). The gene for multiple trichoepitheliomas maps to chromosome 9p21 (16).

Histopathologically, trichoepithelioma is characterized by irregular lobules of proliferating basal cells with distinct keratin cysts (horn cysts), that represent immature hair structures. The keratin cysts may resemble those seen with seborrheic keratosis or keratotic basal cell carcinoma and the tumor may be difficult to differentiate from basal cell carcinoma or squamous cell carcinoma in many instances. The keratin cysts can occasionally incite a foreign body giant cell reaction (7). Electron microscopy and immunohistochemical studies suggest that the tumor arises from hair matrix cells and the horn cysts represent attempts at hair shaft formation (7,8).

Management is surgical excision (13,14,15). If an incisional biopsy confirms trichoepithelioma, definitive surgical removal can be done with less generous margins than for basal cell carcinoma, thus facilitating surgical reconstruction (15). The carbon dioxide laser has been used for multiple lesions (14). Multiple trichoepitheliomas are managed similarly; management varies with the clinical findings.

Trichoepithelioma can be solitary or multiple. In some instances, this benign tumor can spawn basal cell carcinoma (1,2).

Stemberg I, Buckman G, Levine MR, et al. Hereditary trichoepithelioma with basal cell carcinoma. Ophthalmology 1986:93:531-533.

Trichofolliculoma and trichoadenoma are similar hair follicle tumors that rarely affect the eyelids. Trichofolliculoma, a more common lesion than trichoadenoma, is a benign, slow-growing tumor of hair follicle origin that occurs most often in the head and neck region and can involve the eyelid (1,2,3,4,5,6,7,8,9). It accounts for about 1% to 2% of biopsied sweat gland or hair follicle tumors (3,4).

Trichofolliculoma presents as a dome-shaped, skin-colored nodule with a characteristic central pore through which typical cotton-like fine hairs, sometimes white lanugo hairs, protrude. This is a highly diagnostic feature (1,2,3,4,5,6,7,8,9). In the ocular region, it has a predilection for the eyelid margin. Sebum-like material can intermittently drain from the pore. Clinically, it may be confused with sebaceous cysts, nevus, or basal cell carcinoma. Trichofolliculoma does not appear to have any systemic associations.