[Malignant clear cell hidradenoma of the external auditory canal].

A patient with a clear cell (malignant) hidradenoma of the external auditory canal and a detailed review of the literature are presented. Tumours of the ceruminous glands are rare. A sub-classification into distinct histological tumour types is useful with respect to therapy and prognosis. About two-thirds of all these neoplasms are malignant and the frequency of recurrence is very high (50%). Most of the adenomas are not encapsulated. The well differentiated adenocarcinomas (low grade malignancy) of the ceruminous glands can only be distinguished histologically from adenomas by their tendency to invade and infiltrate. Therapy of the ceruminous adenomas is wide excision; the treatment of carcinoma is radical block resection.