Acute Invasive Fungal Rhinosinusitis: Frozen Section Histomorphology and Diagnosis with PAS Stain

Area of Science:

• Pathology
• Infectious Diseases
• Otolaryngology

Background:

• Acute invasive fungal rhinosinusitis (AIFRS) is a severe infection in immunocompromised individuals.
• Rapid diagnosis and surgical intervention are critical for managing AIFRS.
• Frozen section (FS) interpretation for AIFRS diagnosis can be difficult, leading to potential misinterpretations.

Purpose of the Study:

• To identify reasons for diagnostic errors in FS interpretation of AIFRS.
• To explore methods for improving the accuracy of AIFRS diagnosis on FS.
• To evaluate the utility of specific morphologic features and novel staining techniques.

Main Methods:

• Retrospective review of 271 sinonasal biopsy FS slides from suspected AIFRS cases over 16 years.
• Evaluation of morphologic features, including specific necrosis patterns, for diagnostic utility.
• Application of a modified Periodic Acid Schiff's Reaction for Fungi on frozen tissue (PASF-fs) for fungus identification.

Main Results:

• Specific patterns of necrosis were identified as potential indicators of AIFRS.
• Consistent identification of fungal elements in necrotic tissue remains essential but challenging.
• The novel PASF-fs technique effectively stained fungal elements in all 62 positive cases, both retrospectively and prospectively.

Conclusions:

• Accurate diagnosis of AIFRS on FS requires improved identification of fungi in necrotic tissue.
• The modified PASF-fs technique significantly enhances fungus visualization on frozen sections.
• PASF-fs offers a crucial advancement for improving the accuracy of AIFRS diagnosis via FS.