Histopathologic Insights Into Curvularia-Induced Chronic Granulomatous Fungal Sinusitis: A Guide for Surgical...

Area of Science:

• Mycology
• Pathology
• Infectious Diseases

Background:

• Chronic granulomatous fungal sinusitis is a rare infection often seen in subtropical regions.
• Aspergillus flavus is the most common cause globally.
• This condition can extend into orbital and intracranial structures.

Purpose of the Study:

• To describe the histopathologic, microbiologic, and molecular features of chronic granulomatous fungal sinusitis caused by Curvularia.
• To highlight the diagnostic challenges and emerging nature of this infection.
• To inform surgical pathologists about this underrecognized entity.

Main Methods:

• Histopathological examination of 6 cases.
• Microbiologic cultures.
• 28S rRNA gene sequencing of formalin-fixed paraffin-embedded tissue.

Main Results:

• Curvularia was identified as the causative agent in 6 cases, predominantly affecting healthy African Americans in the Southeastern US.
• Histopathology showed multinucleated giant cells, noncaseating granulomas, and short septate hyphae with bulbous swelling.
• Variable morphology and lack of pigmentation in hyphae led to misidentification in 3 cases.
• A characteristic "ghost shell" morphology indicated fungal nonviability.
• Molecular sequencing identified Curvularia lunata, Curvularia spicifera, and Curvularia spp.
• One case showed coinfection with Aspergillus fumigatus.

Conclusions:

• Chronic granulomatous fungal sinusitis caused by Curvularia is an emerging threat in immunocompetent individuals.
• Pathogen persistence occurs despite a significant host response.
• Awareness of expanded geographic range, affected populations, and histopathologic features is crucial for accurate diagnosis and treatment.