trichilemmoma

Trichilemmoma is a rare, benign skin tumor that originates from the hair follicle. It is a type of hamartoma, which is a benign growth consisting of an abnormal mixture of cells and tissues.

Trichilemmomas typically appear as small, firm, and movable nodules on the skin, usually on the face, scalp, or neck. They are often solitary, but in some cases, multiple lesions can occur. The tumors may be pigmented or pale, and may have a smooth, glistening surface.

Trichilemmomas are usually seen in individuals with Cowden syndrome, a genetic disorder that increases the risk of developing multiple benign and malignant tumors. However, they can also occur sporadically in people without a family history of the disorder.

The tumors are composed of a mixture of epithelial cells and arrector pili muscle cells, which are the muscle cells responsible for hair follicle movement. Microscopically, trichilemmomas show characteristic features, including the presence of apocrine-like epithelial cells, which are known as trichilemmocytes.

Trichilemmomas are usually harmless and do not require treatment. However, if the tumors are pigmented or if there is a suspicion of skin cancer, a biopsy may be necessary to confirm the diagnosis. Trichilemmomas should be distinguished from other skin lesions, such as basal cell carcinomas and Bowen's disease.

The exact relationship between trichilemmomas and Cowden syndrome is not fully understood. Nonetheless, individuals with Cowden syndrome should be aware of the potential for developing multiple benign tumors, including trichilemmomas, which requires regular monitoring and screening by a healthcare professional.