Trichoepithelioma, cystic acne and 13-cis-retinoic acid.

Treatment with 13-cis-retinoic acid during 12 weeks of a patient with multiple trichoepitheliomas and acne cystica et comedonica did not affect the number of trichoepitheliomas. The cystic lesions, most of them trichoepitheliomas with only a few non-inflammatory cystic acne lesions, were not affected by this treatment.