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Rasamsonia argillacea brain abscess in a lung transplant recipient: an unexpected infection by an unusual fungal pathogen

Summary

A 65-year-old woman who received a lung transplant developed a rare and serious brain infection caused by an unusual fungus called Rasamsonia argillacea. The infection was difficult to diagnose because it looks similar to more common molds under the microscope. During the investigation of this unexpected infection, doctors discovered that the patient had a rare genetic disorder affecting her immune system that had never been diagnosed. This case highlights how unusual infections can reveal hidden immune system problems.

Background

Rasamsonia argillacea is a rare, emerging thermotolerant filamentous fungus that has been identified as an opportunistic pathogen in immunocompromised individuals, particularly those with chronic granulomatous disease. While Aspergillus species are the most common fungal pathogens in lung transplant recipients, rare and emerging molds are increasingly reported. This case presents an unusual presentation of R. argillacea cerebral abscess in a lung transplant recipient.

Objective

To report and characterize a case of Rasamsonia argillacea brain abscess in a lung transplant recipient and highlight the unique diagnostic and therapeutic challenges associated with this unusual pathogen.

Results

A 65-year-old lung transplant recipient presented with disseminated fungal infections including a 6 cm multi-loculated brain abscess caused by R. argillacea, along with concurrent Aspergillus udagawae and Aspergillus nomius infections. The organism demonstrated resistance to azoles (voriconazole >16 mg/L, isavuconazole >8 mg/L) but susceptibility to echinocandins and amphotericin B. Genetic analysis revealed a homozygous deletion in NCF1 gene, confirming a diagnosis of chronic granulomatous disease.

Conclusion

This is the first reported case of Rasamsonia argillacea cerebral abscess in a lung transplant recipient without pretransplant fungal colonization. The unusual nature of this pathogen prompted immunological investigation that led to the late diagnosis of primary immunodeficiency due to chronic granulomatous disease in a 65-year-old patient.
  • Published in:Medical Mycology Case Reports,
  • Study Type:Case Report,
  • Source: PMID: 41050733, DOI: 10.1016/j.mmcr.2025.100727
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