The pathogenesis of fungus ball has been unclear yet. This study was performed to find a clue to the pathogenesis of fungus ball and to clarify the role of ostiomeatal unit(OMU) obstruction in the fungus ball through the comparative study of fungus ball and chronic bacterial sinusitis.

35 patients with fungus ball(fungus group) and 42 patients with chronic unilateral bacterial sinusitis(bacteria group) were analyzed in terms of radiologic findings and endoscopic findings.

Fungus ball was observed in older patients than chronic bacterial sinusitis(59.7 vs. 41.1). The total Lund scores of bacteria group were higher than those of fungus group(6.0 vs. 4.6)(p=0.009). Lund scores of frontal and anterior ethmoid sinuses and OMU were 0 in fungus group with partial opacity of maxillary sinus. Lund scores of frontal and anterior ethmoid sinuses and OMU in bacteria group were higher than in fungus group regardless of disease severity of maxillary sinus. There was no difference of anatomical variants between lesion side and healthy side in both groups. There was no statistical difference in the scores of endoscopic findings of two groups.

This study may suggest that fungus ball is not associated with the obstruction of OMU comparing with chronic bacterial sinusitis and that fungus ball has another pathogenic mechanism different from that of bacterial sinusitis.