Salivary Duct Carcinoma in the External Auditory Canal Causing Ipsilateral Hearing Loss.

Background: Salivary duct carcinoma (SDC) is a rare aggressive tumor. Most tumors are not confined to the salivary ducts; rather, they invade the major and minor salivary glands. Only a few case reports on such tumors in other primary sites have appeared. Case presentation: A 40-year-old male complained of right hearing loss (a common condition), but we made an extremely rare diagnosis of an SDC in the external auditory canal (EAC). EAC cancers are frequently misdiagnosed. In our patient, the otoscope revealed a smooth, bulging subcutaneous lesion with a non-epithelial defect suggestive of a benign lesion. However, an SDC of the EAC was confirmed through pathological and immunohistochemical analysis. Conclusions: We suggest detailed evaluation of even smooth EAC subcutaneous lesions to avoid erroneous diagnoses. To the best of our knowledge, this is the first report of SDC in the EAC.