Radiological Evaluation of Cases of Fungal Mycetoma in the Maxillary Sinus

<p>Fungal sinusitis is a relatively uncommon clinical entity that may present as sinonasal inflammatory disease. Fungal sinusitis is classified as acute invasive fungal sinusitis, chronic invasive fungal sinusitis, chronic non-invasive fungal sinusitis (mycetoma), and allergic fungal rhinosinusitis, depending on the pathology. Mycetoma is the most common variant, is usually ipsilateral, and commonly involves the maxillary sinuses. Mycetoma is often refractory to non-surgical treatment, and consequently requires endoscopic sinus surgery (ESS) for treatment and to prevent development of invasive fungal sinusitis.</p><p>In the present study, we retrospectively investigated the backgrounds and radiological findings of patients with mycetoma of the maxillary sinus (fungus group) to evaluate the accuracy of preoperative diagnosis by comparison with patients diagnosed with ipsilateral chronic rhinosinusitis (CRS group). The posterior bony wall in the maxillary sinus measured on a CT scan was significantly thicker in the fungus group compared to the CRS group (p = 0.04), whereas there was no significant difference in anterior wall thickness between the two groups (p = 0.21). The incidence of opacification in the affected sinus on CT and that of low signal intensity of the mycetomatous mass on T2-weighted MRI were significantly higher in the fungus group compared to the CRS group (both p < 0.001). Diagnosis of mycetoma based on the low-intensity lesion on T2-weighted MRI (sensitivity 1, specificity 0.968) was more accurate than that using opacification on CT (sensitivity 0.688, specificity 0.839). The number of female patients with no demonstrable opacification on CT was significantly higher in the fungus group than in the CRS group.</p><p>These results indicate the usefulness of MRI for greater diagnostic accuracy for maxillary sinus mycetoma, especially in female patients.</p>