Early and noninvasive diagnosis using serological antigen biomarkers in chronic invasive fungal rhinosinusitis

Background: Chronic invasive form of fungal rhinosinusitis (FRS) is characterized by the invasion of fungal organisms into the sinonasal mucosa in the background of diabetes mellitus and corticosteroid treatment. Although the histopathology has traditionally been used to make a proven diagnosis of invasive fungal infections, the dependence on tissue samples and the slow turnaround time hamper the early confirmation of such infections. Methodology: This is a retrospective case series conducted over 6 years. All patients with a chronic course and immunosuppressive background of FRS diagnosed by radiologic imaging and treated with endoscopic sinus surgery were eligible for inclusion. Data were collected through medical records, including basic characteristics, symptoms and signs, imaging findings, laboratory investigations, pathology, treatment, and outcomes. Results: Fifteen patients with chronic course and immunosuppressive background of FRS diagnosed by radiologic imaging were identified. High values of 1,3-b-D-glucan (BDG) assay were recognized in 5 patients, whereas the other 10 patients with negative findings in the BDG assay showed sinus mycetomas. All the 5 patients showing significant elevations of serum BDG showed positive findings in the polymerase chain reaction (PCR), but only 2 patients were positive in the histopathology. The findings of the BDG assay were consistent with those of the PCR method, which was superior in sensitivity to the histopathology. Conclusion: We first applied BDG assay as a diagnostic tool for chronic invasive FRS. The BDG assay may be useful to distinguish chronic invasive FRS, including its early stage, from noninvasive mycetoma, contributing to timely treatment.