Early Differential Diagnosis of Rhino-Orbito-Cerebral Mucormycosis and Bacterial Orbital Cellulitis: Based on Computed Tomography Findings

PURPOSE To identify significant clinical and radiological findings that distinguish rhino-orbito-cerebral mucormycosis (ROCM) from bacterial orbital cellulitis (BOC). METHODS This study was retrospective, multicenter, case-control study that enrolled 34 cases; 14 cases were diagnosed with ROCM and 20 cases were diagnosed with BOC at three different tertiary hospitals between 2005 and 2013. The medical records of all 34 cases were reviewed. The initial clinical manifestations (eyelid swelling, ptosis, extraocular muscle [EOM] limitation, conjunctival injection, and chemosis) and computed tomography (CT) findings (sinus mucosal thickening, full opacification, and air-fluid level) of both diseases were compared. RESULTS Patients with diabetes mellitus (DM) and hypertension (HTN) showed higher incidence rates of ROCM than BOC (DM: p < 0.001, HTN: p = 0.036). ROCM cases exhibited more frequent EOM limitation than cases with BOC (100.0% vs. 66.7%, p = 0.024) but less frequent eyelid swelling (35.7% vs. 90.0%, p = 0.002). However, the incidence rates of ptosis, conjunctival injection, and chemosis exhibited no differences between the diseases. Abnormal CT findings were observed in the sinuses of all patients with ROCM, whereas 12 patients with BOC had sinus abnormalities (100.0% vs. 60.0%, p = 0.011). Thickening of the sinus mucosa was more frequent in patients with ROCM than in those with BOC (92.9% vs. 45.0%, p = 0.009). No significant differences in full opacification or air-fluid level were detected between the groups. CONCLUSIONS The differential diagnosis of ROCM and BOC is difficult. Nevertheless, physicians should consider ROCM when a patient with suspected orbital cellulitis presents with EOM limitation without swollen eyelids or thickening of the sinus mucosa on a CT scan.