Multiple trichoepitheliomas associated with a novel heterozygous mutation in the CYLD gene as an adjunct to the histopathological diagnosis.

Multiple trichoepitheliomas (TEs), especially in the familial setting, have been associated with germline heterozygous mutations in the CYLD gene. Heterozygous germline CYLD mutations and loss of heterozygosity of the CYLD gene in the TE tumor cells have been recently demonstrated in some of the multiple TE cases irrespective of a family history. The histopathological differential diagnosis of TE from basal cell carcinoma may be difficult especially in cases with multiple TEs. Immunohistochemical markers may be used, although some with conflicting results. We describe a 35-year-old woman with multiple facial TEs, in whom the molecular genetic analysis revealed a novel heterozygous c.1843delT mutation in the CYLD gene. This frameshift mutation was also present in a heterozygous state in the TE tumor cells. The demonstration of a novel CYLD mutation was used as an adjunct to the histopathological diagnosis in this case.