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Extensive erythematous plaques of fungal origin in an overseas student: Cutaneous manifestation of coccidioidomycosis

Summary

A 21-year-old student studying in Arizona developed unusual skin rashes months after returning to China. Doctors had difficulty diagnosing the condition because it lacked typical symptoms of the fungal infection coccidioidomycosis. By using multiple diagnostic methods including DNA sequencing and fungal culture, they identified the infection as caused by Coccidioides posadasii. When the initial antifungal drug didn’t work, testing showed the fungus was resistant, so they switched to a different antifungal called voriconazole, which successfully cured the infection after 12 months.

Background

Coccidioidomycosis is an endemic mycosis caused by Coccidioides posadasii and Coccidioides immitis, predominantly found in arid regions of the Americas. Cases in non-endemic regions are increasingly reported among travelers and international students. The rarity of the disease outside endemic areas and non-specific clinical symptoms often complicate diagnosis.

Objective

To present a case of C. posadasii infection contracted during study abroad with atypical cutaneous manifestations and to demonstrate the clinical significance of combining multiple diagnostic methods for effective treatment.

Results

mNGS identified C. posadasii on day 6, confirmed by histopathology showing spherules with endospores and by ITS sequencing. Initial fluconazole treatment (400 mg/day for 6 months) was ineffective with MIC of 8μg/mL. Drug sensitivity testing showed voriconazole MIC of 0.06μg/mL. After switching to voriconazole 300 mg twice daily, skin lesions subsided after 12 months with three consecutive negative mycological tests.

Conclusion

This case demonstrates the importance of using multiple diagnostic approaches (culture, histopathology, molecular sequencing) for identifying atypical fungal infections in non-endemic regions. Drug sensitivity testing was critical for guiding treatment decisions when conventional therapy failed, ultimately leading to successful outcome with voriconazole.
  • Published in:Medical Mycology Case Reports,
  • Study Type:Case Report,
  • Source: PMID: 39430957, DOI: 10.1016/j.mmcr.2024.100674
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