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Subcutaneous phaeohyphomycosis caused by Phaeoacremonium rubrigenum in an immunosuppressed patient
T Matsui1, K Nishimoto, S Udagawa
1Department of Dermatology, Kumamoto University School of Medicine, Kumamoto, Japan.
Background:
Phaeohyphomycosis refers to infection by dematiaceous fungi with pigmented hyphae or yeast-like cells in the tissue. In humans, this disease is usually considered to be an opportunistic infection. The causal agents of phaeohyphomycosis include numerous species belonging to different genera and they are increasing as a result of the development of intensive medical therapy.
Observation:
We report the case of a 61-year-old Japanese female under corticosteroid treatment for malignant rheumatoid arthritis. An asymptomatic subcutaneous tumor developed on the back of her left foot. Histological examination of the excised material revealed mixed cell granuloma (H&E) and the presence of branched hyphal elements (periodic acid-Schiff). A fungus grown in pure culture was identified as Phaeoacremonium rubrigenum.
Conclusion:
The hyphomycete genus, Phaeoacremonium, was proposed in 1996 by Crous et al. Three species belonging to this genus have been isolated from clinical specimens: P. inflatipes, from a human toenail, human synovial fluid and human mycetoma of the foot, P. parasiticum, from a subcutaneous lesion on a kidney transplant patient and several other sources, and P. rubrigenum, from a human patient with pneumonia. To our knowledge, however, this is the first report of phaeohyphomycosis caused by Phaeoacremonium rubrigenum.
Insights
This study reports the first case of phaeohyphomycosis caused by Phaeoacremonium rubrigenum in an immunocompromised patient. The opportunistic fungal infection presented as a subcutaneous tumor, highlighting the need for awareness of rare fungal pathogens.
Area of Science:
- Medical Mycology
- Infectious Diseases
Background:
- Phaeohyphomycosis is an infection caused by dematiaceous fungi, often opportunistic, with increasing incidence due to intensive medical therapies.
- The causal agents are diverse, belonging to various fungal genera.
Observation:
- A 61-year-old female on corticosteroid therapy for rheumatoid arthritis developed an asymptomatic subcutaneous tumor on her foot.
- Histological examination revealed granuloma and fungal hyphae.
Findings:
- Fungal culture identified Phaeoacremonium rubrigenum as the causative agent.
- This marks the first documented instance of phaeohyphomycosis attributed to Phaeoacremonium rubrigenum.
Implications:
- Expands the spectrum of known clinical manifestations for Phaeoacremonium species.
- Highlights the importance of considering rare fungal pathogens in immunocompromised individuals presenting with subcutaneous lesions.