External auditory canal metastasis revealing bronchogenic carcinoma: A case report and literature review.

This report presents a rare case of bronchogenic adenocarcinoma with initial metastasis in the external auditory canal. The patient, a 64-year-old man with a history of bladder urothelial carcinoma, initially presented with a persistent right otitis externa. Otoscopic examination revealed a mass obstructing the right external auditory canal. The temporal bone computed tomography scan revealed a mass that completely obstructed the right external auditory canal and extended into the middle ear. A biopsy showed a poorly differentiated adenocarcinoma of bronchogenic origin, confirmed by positive immunohistochemical staining for cytokeratin 7 and Thyroid transcription factor-1. Further imaging revealed a large tumor mass in the lung involving the mediastinum and parenchyma, along with carcinomatous lymphangitis and cerebral metastasis. Histopathological examination of the primary lung tumor confirmed a poorly differentiated adenocarcinoma with similar features to the metastasis in the external auditory canal. The tumor was staged as T4N2M1c, and the patient underwent local external-beam radiation therapy with chemotherapy.