Radiologically occult nasopharyngeal carcinoma: the importance of clinical suspicion and repeat biopsy.

A man in his 40s undergoing long-term otolaryngology surveillance following an initial diagnosis of a left-sided nasopharyngeal lesion classified as carcinoma in situ re-presented approximately 3 years later with intermittent aural fullness and tinnitus. Flexible nasendoscopy demonstrated subtle unilateral polypoidal change at the left eustachian tube orifice and fossa of Rosenmüller (FOR), while MRI remained non-diagnostic, with no discrete nasopharyngeal mass or skull base abnormality. Given persistent focal endoscopic abnormalities discordant with reassuring imaging, targeted endoscopic biopsy was undertaken and confirmed non-keratinising nasopharyngeal carcinoma. Supplementary testing with Epstein-Barr encoding region in situ hybridisation and external specialist pathologist review reclassified the earlier biopsy as early invasive disease rather than carcinoma in situ. Staging with positron emission tomography demonstrated no fluorodeoxyglucose-avid primary lesion or metastatic disease. This case highlights that early nasopharyngeal carcinoma may be occult across multiple imaging modalities and that persistent clinical suspicion should prompt repeat targeted biopsy.