DOI: https://doi.org/10.36347/sasjm.2026.v12i08.010

Pages: 821-823

Sinonasal fungal ball is a non-invasive form of fungal rhinosinusitis that usually occurs in immunocompetent adults and most commonly affects a single paranasal sinus, especially the maxillary sinus. Extensive unilateral involvement of the nasal cavity in an adolescent is unusual and may mimic a tumoral lesion on initial assessment. We report the case of a 16-year-old boy presenting with progressive left nasal obstruction for 3 years. Rhinoscopy showed a polypoid lesion filling the left nasal cavity. Computed tomography revealed a large heterogeneous expansile lesion centered in the left nasal fossa, with spontaneous internal hyperdense foci and no significant post-contrast enhancement, associated with ipsilateral maxillary and ethmoidal extension. Magnetic resonance imaging demonstrated predominantly high T1 signal, marked T2 hypointensity/signal void, and absence of appreciable internal gadolinium enhancement. These combined imaging findings were in favor of a sinonasal fungal ball. This case highlights the diagnostic value of combining CT and MRI when evaluating a unilateral sinonasal mass with a pseudo-tumoral appearance.