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Thursday 3 January 2013



Definition: Trichilemmoma is a cutaneous benign adnexal tumors that differentiates toward cells of the outer root sheath. The lesion is often seen in the face and neck region.

They are a benign lesion derived from hair follicles. The lesions are symmetrical and show increasing clear cytoplasm moving deeper into the dermis due to glycogenation. Papillomatosis, hyperkeratosis, and peripheral palisading are also common.

Cowden syndrome

Multifocal occurrence is associated with Cowden syndrome , patients with which exhibit hamartomatous intestinal polyposis as well as tricholemmoma.

Cowden syndrome (multiple hamartoma syndrome) is characterized by multiple hamartomas, soft tissue tumors, skin tumors, breast cancer, and GI polyps. It is caused by PTEN mutations.

Trichilemmomas, especially when multiple, are associated with Cowden syndrome.


- outer root sheath differentiation
- adnexal tumor
- Cowden synrome / Cowden disease
- PTEN mutation


- trichilemmoma

- trichilemmoma arising in nevus sebaceus

- desmoplastic trichilemmoma


- desmoplastic trichilemmoma

Differential diagnosis

- clear cell acanthoma
- trichilemmal carcinoma
- trichilemmal horn


- Cowden disease

See also

- cutaneous tumors

  • cutaneous adnexal tumors
    • cutaneous follicular tumors