Trichoepithelioma

Updated: Sep 25, 2018
  • Author: Victor G Prieto, MD, PhD; Chief Editor: William D James, MD  more...
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Overview

Background

Trichoepithelioma is a benign adnexal neoplasm. Cases associated with Brooke-Spiegler syndrome are caused by mutations of the cylindromatosis oncogene (CYLD), which maps to 16q12-q13. [1, 2, 3] A 2006 study has suggested that abnormalities in this gene may result in one of 3 syndromes: Brooke-Spiegler syndrome, familial cylindromatosis, and multiple familial trichoepithelioma. [4]  Furthermore, some cases of patients with multiple trichoepitheliomas appear to be sporadic and not related with familial incidence. [5]

A 2009 study reports a novel missense mutation in the CYLD gene, heterozygous nucleotide G-->A transition at position 2,317 in exon 17, in a Chinese family with multiple familial trichoepithelioma. [6] Additionally, a novel splicing mutation in the CYLD gene (IVS12 + 1 G-->A) has been reported in a Taiwanese family with multiple familial trichoepithelioma. [7]

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Pathophysiology

Studies have indicated that CYLD encodes a deubiquitinating enzyme that negatively regulates the nuclear factor (NF)–kappaB and c-Jun N-terminal kinase (JNK) pathways. [8] Due to the presence of significant numbers of Merkel cells within the tumor nest and the detection of a sheath of CD34-positive dendrocytes around the tumor nests, it appears that trichoepithelioma differentiates toward or derives from hair structures, particularly the hair bulge. Rare instances of tumors resembling trichoepithelioma have been reported in animals. [9]

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Etiology

The gene involved in basal cell carcinoma (PTCH, human patched gene located on band 9q22.3) appears to participate in the pathogenesis of trichoepithelioma. [10]

Brooke-Spiegler syndrome patients have a high incidence of multiple skin appendage tumors such as cylindroma, trichoepithelioma, and spiradenoma. These patients may show mutations of the CYLD gene (cylindromatosis gene) that map to 16q12-q13. [11]

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Epidemiology

US frequency

One dermatopathology laboratory reported 2.14 and 2.75 cases of trichoepithelioma per year (9000 specimens).

Sex

Since trichoepithelioma is inherited in an autosomal dominant fashion, males and females receive the gene equally, but because of lessened expressivity and penetrance in men, most patients are women.

Age

Trichoepithelioma typically occurs in young to aging adults; however, the hereditary form may be seen in younger individuals. A single case study has reported a congenital lesion of desmoplastic trichoepithelioma. [12]

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Prognosis

Slow growth is characteristic of trichoepithelioma. Partial removal may result in persistence or recurrence. Although rare, trichoepitheliomas can develop high-grade carcinomas and mixed (epithelial/sarcomatous) tumors. [13, 14] Familial trichoepithelioma has shown an aggressive, recurrent behavior in rare cases.

In cases of multiple trichoepitheliomas, the lesions may cause disfigurement because of involvement of the face. The rare cases of trichoepithelioma described as having aggressive behavior (ie, ulceration, recurrence) are probably follicular tumors within the basal cell nevus syndrome and not trichoepithelioma.

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Patient Education

Inform the patient that some degree of scarring will be present after trichoepithelioma treatment.

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