Disseminated Histoplasmosis Presenting as Pyrexia of Unknown Origin in a Rheumatoid Arthritis Patient

Area of Science:

• Medical Mycology
• Rheumatology
• Infectious Diseases

Background:

• Methotrexate is a common immunosuppressant for rheumatoid arthritis.
• Prolonged fever in immunosuppressed patients warrants thorough investigation.
• Rheumatoid arthritis patients are at increased risk for opportunistic infections.

Observation:

• A 56-year-old female with a 9-year history of rheumatoid arthritis on methotrexate presented with a month of high-grade fever.
• Extensive evaluation failed to identify a source of infection, leading to a diagnosis of pyrexia of unknown origin.
• Bone marrow aspiration suggested fungal elements, prompting further specific testing.

Findings:

• Urine testing detected Histoplasma antigen, confirming disseminated histoplasmosis.
• The patient's fever resolved within two weeks of treatment with liposomal amphotericin B.
• The patient was transitioned to oral itraconazole for further management.

Implications:

• This case highlights the importance of considering opportunistic fungal infections, like histoplasmosis, in immunosuppressed patients.
• Urine antigen testing is a valuable tool for diagnosing histoplasmosis in complex cases.
• Prompt diagnosis and appropriate antifungal therapy are crucial for favorable outcomes in disseminated fungal infections.