Metachronous nasopharyngeal carcinoma following sinonasal inverted papilloma – a diagnostic enigma

Background: Inverted papilloma (IP) is a benign Schneiderian epithelial tumour with a well-recognized potential for recurrence and malignant transformation, most commonly to squamous cell carcinoma (SCC). Carcinoma arising in the nasopharynx after prior IP is exceedingly rare, and distinguishing malignant conversion from a metachronous nasopharyngeal carcinoma (NPC) poses a diagnostic challenge. Case report: We report a rare, interesting case of a nasopharyngeal lesion with histopathological features of non-keratinizing SCC in a patient previously treated surgically for sinonasal IP. Conclusion: Differentiating malignant transformation of IP from a metachronous malignancy is complex. In this case, the short interval between diagnoses, anatomical separation, and absence of Schneiderian features favour interpretation as a metachronous NPC, highlighting the importance of continued surveillance and prompt evaluation of new symptoms in patients treated for IP.