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Published on: June 13, 2018
Histopathological techniques for the diagnosis of combat-related invasive fungal wound infections
Sarah M Heaton1, Amy C Weintrob2, Kevin Downing1
1Department of Pathology, Walter Reed National Military Medical Center, 8901 Wisconsin Avenue, Bethesda, MD 20814 USA.
Background:
Effective management of trauma-related invasive fungal wound infections (IFIs) depends on early diagnosis and timely initiation of treatment. We evaluated the utility of routine staining, histochemical stains and frozen section for fungal element identification.
Methods:
A total of 383 histopathological specimens collected from 66 combat-injured United States military personnel with IFIs were independently reviewed by two pathologists. Both periodic acid-Schiff (PAS) and Gomori methenamine silver (GMS) stains were used on 74 specimens. The performance of the two special stains was compared against the finding of fungal elements via any histopathological method (ie, special stains or hematoxylin and eosin). In addition, the findings from frozen sections were compared against permanent sections.
Results:
The GMS and PAS results were 84 % concordant (95 % confidence interval: 70 to 97 %). The false negative rate of fungal detection was 15 % for GMS and 44 % for PAS, suggesting that GMS was more sensitive; however, neither stain was statistically significantly superior for identifying fungal elements (p = 0.38). Moreover, 147 specimens had frozen sections performed, of which there was 87 % correlation with permanent sections (60 % sensitivity and 98 % specificity). In 27 permanent sections, corresponding cultures were available for comparison and 85 % concordance in general species identification was reported.
Conclusions:
The use of both stains does not have an added benefit for identifying fungal elements. Furthermore, while the high specificity of frozen section may aid in timely IFI diagnoses, it should not be used as a stand-alone method to guide therapy due to its low sensitivity.
Insights
Accurate diagnosis of invasive fungal wound infections (IFIs) is crucial. Gomori methenamine silver (GMS) and periodic acid-Schiff (PAS) stains showed similar efficacy, while frozen sections offer high specificity but low sensitivity for IFI diagnosis.
Area of Science:
- Medical Mycology
- Pathology
- Infectious Diseases
Background:
- Effective management of trauma-related invasive fungal wound infections (IFIs) relies on early diagnosis and prompt treatment.
- Histopathological methods, including routine staining, histochemical stains, and frozen sections, are vital for identifying fungal elements.
Purpose of the Study:
- To evaluate the utility of routine staining, histochemical stains (PAS and GMS), and frozen sections for identifying fungal elements in IFIs.
- To compare the diagnostic performance of different histopathological methods for IFIs.
Main Methods:
- A review of 383 histopathological specimens from 66 combat-injured personnel with IFIs.
- Independent review by two pathologists using periodic acid-Schiff (PAS) and Gomori methenamine silver (GMS) stains on 74 specimens.
- Comparison of frozen section findings against permanent sections and available cultures.
Main Results:
- Gomori methenamine silver (GMS) and periodic acid-Schiff (PAS) stains showed 84% concordance, with GMS having a lower false-negative rate (15% vs. 44%).
- Neither stain demonstrated statistically significant superiority (p=0.38).
- Frozen sections correlated with permanent sections with 87% agreement (60% sensitivity, 98% specificity).
Conclusions:
- Using both GMS and PAS stains does not offer additional benefit for identifying fungal elements in IFIs.
- Frozen sections, despite high specificity, should not be used alone for guiding IFI therapy due to low sensitivity.
