Sneaking Its Way Up: External Auditory Canal Involvement by an Otherwise Inconspicuous Nasopharyngeal Carcinoma via Spread Through the Eustachian Tube

External auditory canal and middle ear involvement is an uncommon initial presentation for early primary nasopharyngeal carcinoma. Previously reported cases were only associated with advanced skull base erosion or recurrence after radical treatment. We present a patient with nasopharyngeal carcinoma with a small inconspicuous primary tumour in the nasopharynx without skull base erosion, but who first presented with auditory symptoms and was found to have biopsy-proven external auditory canal involvement. Contrast-enhanced magnetic resonance imaging and 18F-fluorodeoxyglucose-positron emission tomography clearly demonstrated the route of extension via the Eustachian tube into the middle ear and mastoid air cells. This report highlights the importance of heightened vigilance for nasopharyngeal carcinoma and careful nasal endoscopic examination when encountering an undifferentiated carcinoma of the external auditory canal, especially in areas endemic for nasopharyngeal carcinoma. Similarly, otoscopic examination and modern imaging techniques such as magnetic resonance imaging or positron emission tomography are invaluable for investigating suspected nasopharyngeal carcinoma that presents as auditory symptoms.