Rheumatoid arthritis complicated with cervical actinomycosis and ureteral obstruction: A case report and literature review.

Actinomycosis is a rare chronic granulomatous disease characterized by granuloma formation and tissue fibrosis with sinus tracts, often misdiagnosed due to its similarity to many infectious and non-infectious diseases. This report presents a case of a 60-year-old female with more than 10 years history of rheumatoid arthritis who developed actinomycosis infection after long-term treatment with immunosuppressants and biologics, including methotrexate, leflunomide, and infliximab, leading to recurrent joint pain, poorly controlled rheumatoid arthritis activity, and persistent elevation of white blood cell counts. Abdominal CT revealed a pelvic mass and right ureteral dilation. Pathological examination of cervical tissue showed significant neutrophil infiltration and sulfur granules, indicating actinomycosis. The patient received 18 months of doxycycline treatment for the infection and continued rheumatoid arthritis therapy with leflunomide, hydroxychloroquine sulfate, and tofacitinib, resulting in improved joint symptoms and normalized white blood cell counts. After 2 years of follow-up, the patient remained stable with no recurrence. This case highlights the importance of clinicians being vigilant for infections, particularly chronic, occult infections from rare pathogens, in rheumatoid arthritis patients on potent immunosuppressants and biologics, advocating for early screening and diagnosis.