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The impact of osteoarticular invasion by Coccidioides Sp disseminated infection

Summary

A 48-year-old man from Mexico developed a serious fungal infection caused by Coccidioides, which spread from his lungs to his skin, bones, and joints, causing pain and swelling. Despite having a normally functioning immune system, he developed progressive disease that was initially misdiagnosed as rheumatoid arthritis. After switching to the antifungal medication fluconazole, his condition improved dramatically, with symptoms resolving within several months of treatment.

Background

Coccidioidomycosis is a systemic fungal infection caused by Coccidioides immitis and C. posadasii, endemic to southwestern United States and Mexico. While most cases are asymptomatic or resolve spontaneously, 0.5-2% progress to disseminated disease, particularly in immunocompromised individuals. Skeletal coccidioidomycosis accounts for approximately half of disseminated infections with the spine being the preferred site.

Objective

To present an unusual case of disseminated coccidioidomycosis in an immunocompetent patient presenting with simultaneous pulmonary, dermatological, and osteoarticular manifestations. The case highlights the progression of fungal infection to bone and joint tissue despite immunocompetent status.

Results

Histopathological findings revealed numerous spherules measuring 20-40 μm in the dermis with intense inflammatory process, confirmed by Grocott staining. MRI imaging demonstrated heterogeneous granulomatous lesion with joint lysis at the proximal interphalangeal joint of the fourth finger. Treatment with fluconazole 400 mg/day resulted in complete remission of dermatological lesions and significant improvement in joint symptoms with 85% overall remission at 10 months.

Conclusion

This case demonstrates an unusual presentation of disseminated coccidioidomycosis in an immunocompetent patient with pulmonary, osteoarticular, and dermatological manifestations. Initial immunosuppressive medications may have contributed to pathogen dissemination, and HLA-B27 positivity likely contributed to reactive arthritis manifestations. Long-term azole therapy (fluconazole) proved effective for managing osteoarticular involvement.
  • Published in:Medical Mycology Case Reports,
  • Study Type:Case Report,
  • Source: PMID: 40584595, DOI: 10.1016/j.mmcr.2025.100710
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