Benign dermal cylindroma of the external auditory canal: a clinicopathological report.

Considerable confusion exists regarding the nature of benign dermal cylindroma of the external auditory canal. In the past, authors have used the term cylindroma to refer to malignant lesions such as adenoid cystic carcinoma. Benign dermal cylindroma is a specific clinical entity consisting of benign tumors arising from the epidermal appendages; however, whether they are apocrine- or eccrine-derived is not conclusively known. Six per cent are reported to be related to the ear. Histologically they are characterized by cords of basophilic cells, hyaline material, and cystic duct-like structures. Rarely, cases of malignant degeneration are reported. However, for the most part, these lesions are benign and should be treated with complete local excision. Radiotherapy may be useful in treating massive lesions not amenable to surgery.