Diagnosis of a maxillary sinus fungus ball without intralesional hyperdensity on computed tomography.

OBJECTIVES/HYPOTHESIS: Maxillary sinus fungus ball (MSFB) is the most common type of noninvasive fungal rhinosinusitis. Surgical removal of the ball achieves good outcomes. Making a rapid and accurate diagnosis is important to avoid unnecessary medical therapy. Intralesional hyperdensity (IH) on computed tomography (CT) is reportedly a good indicator. The aim of this study was to evaluate the diagnostic features of MSFB without IH on preoperative CT images. STUDY DESIGN: Retrospective database review. METHODS: Two hundred fifty-eight patients with histopathological evidence of a sinus fungal ball were retrospectively investigated. Forty-seven of 222 patients with MSFB did not show IH on preoperative CT images and were enrolled in the MSFB group. Forty-one patients with unilateral nonfungal chronic rhinosinusitis were enrolled in a control group. CT features previously reported to have diagnostic significance were evaluated. RESULTS: Sclerosis of the lateral sinus wall, erosion of the inner sinus wall, and irregular surface of the material were significantly more common in the MSFB group than in the control group. In the subgroup of patients with total opacification in the maxillary sinus, the sensitivity, specificity, and positive and negative predictive values for erosion of the inner sinus wall were more than 90%. In the subgroup with partial opacification, the sensitivity, specificity, and positive predictive value of an irregular surface of the material were more than 80%. CONCLUSIONS: We have devised an algorithm to help diagnose MSFB without IH on preoperative CT images. Use of this algorithm would improve the diagnostic accuracy and ensure appropriate treatment. LEVEL OF EVIDENCE: 4 Laryngoscope, 129:1041-1045, 2019.