The role of galactomannan Aspergillus antigen in diagnosing acute invasive fungal sinusitis

Background Pathologic diagnosis remains the gold standard for final diagnosis of acute invasive fungal sinusitis (AIFS); however, other less invasive tests could suggest the presence of AIFS in at-risk populations where early diagnosis is crucial. Serum galactomannan Aspergillus antigen has been shown to correlate with a diagnosis of invasive pulmonary aspergillosis; however, it has not adequately been evaluated in regard to AIFS. The objective of this study is to evaluate the statistical relevance of galactomannan in predicting diagnosis of AIFS. Methods This study was a retrospective review of pathologic records using Co-Path from 2006 to 2017, incorporating 2 separate searches with designated criteria identifying patients who received pathologic evaluation for invasive fungal sinusitis. Electronic medical records were subsequently reviewed. After exclusions isolating at-risk populations and removing duplications, 78 cases were reviewed using the indicated search criteria. Of these, 38 met further criteria of having had both pathologic evaluation and galactomannan analysis. Statistical variables were assessed, as well as all-cause mortality. Peak and closest galactomannan levels were evaluated. Results Overall, galactomannan had a sensitivity of 44.8% (95% confidence interval [CI], 26.5% to 64.3%), specificity of 100% (95% CI, 66.4% to 100%), positive predictive value of 100% (95% CI, 74.3% to 100%), and negative predictive value of 36% (95% CI, 18.0% to 57.5%). No significant association was observed in galactomannan status and mortality in this patient population. Conclusion Positive serum galactomannan can be an indication of AIFS in patients with a high clinical suspicion. In our study, a positive galactomannan always correlated with a positive pathologic diagnosis. However, given its low sensitivity, one must use caution in relying on galactomannan as a screening tool in diagnosis of AIFS.