A trichodiscoma is a rare, benign follicular hamartoma that presents as an asymptomatic 2- to 4-mm skin-colored papule on the face, scalp, or upper trunk. The exact incidence of trichodiscoma is unknown, and no sex predilection has been identified. Multiple trichodiscomas may be inherited as part of the autosomal dominant Birt-Hogg-Dubé syndrome (BHD), caused by a mutation in the FCLN gene on chromosome 17. This gene is responsible for encoding a tumor suppressor protein called folliculin.
Patients with BHD present in the third or fourth decade of life with multiple fibrofolliculomas, trichodiscomas, perifollicular fibromas (fibrous papules or angiofibromas), acrochordons, and, rarely, connective tissue nevi. These patients have an increased risk of renal cell carcinoma, pulmonary cysts, and pneumothoraces and may have increased rates of colonic polyposis and medullary carcinoma of the thyroid. It is now thought that fibrofolliculomas, perifollicular fibromas, and trichodiscomas may be different developmental stages of one tumor derived from the sebaceous mantle, called a mantleoma.
Trichodiscomas are not typically seen in the pediatric population as the majority arise within the third and fourth decades of life.
Trichodiscoma
Alerts and Notices
Synopsis
Codes
ICD10CM:
D23.9 – Other benign neoplasm of skin, unspecified
SNOMEDCT:
254700008 – Trichodiscoma
D23.9 – Other benign neoplasm of skin, unspecified
SNOMEDCT:
254700008 – Trichodiscoma
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Diagnostic Pearls
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Differential Diagnosis & Pitfalls
- Fibrofolliculoma – Clinically may be indistinguishable from trichodiscoma. These skin-colored lesions are often more vertically oriented than horizontally, with epithelial strands extending radially into the stroma. They may have dilated / cystic-like infundibula filled with keratin seen on histology, as well as fibrillary collagenous or mucinous stroma with minimal elastic tissue surrounding the infundibula. Shave biopsy can help determine the diagnosis.
- Trichofolliculoma – Clinically may be indistinguishable from trichodiscoma. Often presents as a smooth hemispheric papule with a central depression where a hair may emerge. Usually located on the central face of an adult. Shave biopsy can help determine the diagnosis.
- Perifollicular fibroma – Clinically may be indistinguishable from trichodiscoma. These lesions often present as single or multiple papules that are most commonly located on the head and neck. Shave biopsy can help determine the diagnosis.
- Trichilemmoma
- Trichoepithelioma
- Dermal nevus
- Fibrous papule
- Dermatofibroma
- Other adnexal tumors may also present as skin-colored papules; biopsy is necessary for diagnosis.
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References
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Last Reviewed:12/18/2021
Last Updated:01/09/2022
Last Updated:01/09/2022
Trichodiscoma