Desmoplastic trichilemmoma
that presents as a solitary, skin colored lesion on the midface. Lesions may appear smooth or verrucous. Lesions may occur alongside trichoepitheliomas. They may also occur on genital skin and resemble condyloma acuminata.
Dr. Donna Bilu Martin
Histopathology reveals downward lobular growth of the epidermis. Keratinocytes are clear secondary to periodic acid-Schiff (PAS)–positive glycogen in the cells. In desmoplastic trichilemmoma, small clusters of cells are arranged in an infiltrative pattern that resembles invasive carcinoma. Often, the desmoplastic areas are surrounded by benign-appearing trichilemmomas, which helps to make the diagnosis. Desmoplastic trichilemmomas can also occur within nevus sebaceous. As trichilemmoma is a benign growth; no treatment is needed. However, if further removal is desired, electrodesiccation, cryotherapy, shave removal, or excision are treatment options. Rarely seen, the malignant counterpart to trichilemmomas is a trichilemmal carcinoma, which requires surgical excision or Mohs.
The appearance of multiple trichilemmomas is a marker for Cowden syndrome. Cowden syndrome is a rare autosomal dominant disorder in which there is a mutation in a tumor-suppressor gene called PTEN. Patients may have oral mucosal papillomas, sclerotic fibromas, acral keratotic papules, and are at risk for the development of adenocarcinoma of the breast, gastrointestinal tract, and thyroid.
Trichoepithelioma is a benign neoplasm derived from follicular germ cells that presents as a skin-colored papule on the midface, especially the nose. Multiple trichoepitheliomas are a marker for Brooke-Spiegler syndrome. A desmoplastic trichoepithelioma is a variant that has stromal sclerosis on pathology. It is a benign lesion, although may be difficult to differentiate from sclerosing basal cell or microcystic adnexal carcinoma.
Angiofibroma, or fibrous papule, is a commonly seen, benign, skin-colored papule also often occurring on the nose. They can be treated for cosmetic purposes. Multiple lesions are associated with tuberous sclerosis.
Dr. Bilu Martin is a board-certified dermatologist in private practice at Premier Dermatology, MD, in Aventura, Fla. More diagnostic cases are available at edermatologynews.com. To submit a case for possible publication, send an email to dermnews@mdedge.com.