It is rare for a malignant tumor to be diagnosed when tinnitus and dizziness are with initial symptoms. We experienced a case diagnosed internal auditory canal metastasis of lung cancer. The patient was a 39-year-old woman. Left-sided tinnitus and dizziness appeared, and she consulted our hospital. Pure tone audiometry identified left sensory neural hearing loss at a high frequency. She was diagnosed with sudden deafness, and, in spite of steroid therapy, her hearing ability and symptoms subsequently aggravated. We located a tumor in the left internal auditory canal by MRI, and diagnosed the case as otological symptoms caused by the metastasis of lung cancer to the internal auditory canal by PET-CT. This is the first report in Japan where by the metastasis of lung cancer has been found to be the main reason for otological symptoms. When hearing impairment shows further exacerbation in spite of treatment, we should consider a tumor of the internal auditory canal in the differential diagnosis.
