Histopathologic findings in the temporal bones of a 71-year-old male with bilateral deafness and facial paralysis due to DMLC originated from transitional cell carcinoma of the renal pelvis are presented. The patient first noticed progressive bilateral hearing loss on July 17, 1986 and became totally deaf bilaterally 4 weeks later. Then, he experienced facial weakness on the left side, which progressed to complete paralysis bilaterally. These symptoms were followed by other cranial nerve paralyses and various meningeal symptoms. He died on Octorber 8, 1986 about 2 months after the onset of otologic symptoms. The temporal bones were removed 3 hours postmortem for study. There are almost identical histopathologic findings in the both temporal bones. The internal auditory meatus is filled with the neoplastic tissue, by which the vestibulocochlear nerve bundles are completely replaced. The neoplastic cells diffusely infiltrate the modioli and the Rosenthal canals of the cochlea through the cribrose areas and reach the scala tympani of the basal turns bilaterally. The facial nerve is completely destroyed from the internal auditory meatus to the geniculate portion bilaterally by neoplastic cell invasion. External and middle ears are free of tumor.
