Occult recurrence of sinonasal inverted papilloma masked by a mucocele: a case report.

BACKGROUND

Sinonasal inverted papilloma (SNIP) is a benign but locally aggressive tumor. Although recurrence typically presents as a solid mass on imaging, atypical manifestations may pose diagnostic difficulties.

CASE PRESENTATION: A 56-year-old man with previous SNIP resection presented with progressive left orbital pain. Computed tomography (CT) and magnetic resonance imaging (MRI) showed an expansile cystic lesion in the left frontal and ethmoid sinuses, initially interpreted as a mucocele. Intraoperatively, a papillomatous lesion was identified at the frontal sinus ostium. Pathology confirmed SNIP with focal mild cytologic atypia.

CONCLUSION

SNIP recurrence can be masked by a secondary mucocele, leading to negative preoperative tests. Our experience suggests that in high-risk patients, thin-section MRI (≤1-2 mm) may improves detection, and surgical exploration with cyst wall biopsy should be performed when clinical suspicion remains high.