RESUMO
BACKGROUND: Gout and seronegative rheumatoid arthritis (SNRA) are two distinct inflammatory joint diseases whose co-occurrence is relatively infrequently reported. Limited information is available regarding the clinical management and prognosis of these combined diseases. CASE SUMMARY: A 57-year-old woman with a 20-year history of joint swelling, tenderness, and morning stiffness who was negative for rheumatoid factor and had a normal uric acid level was diagnosed with SNRA. The initial regimen of methotrexate, leflunomide, and celecoxib alleviated her symptoms, except for those associated with the knee. After symptom recurrence after medication cessation, her regimen was updated to include iguratimod, methotrexate, methylprednisolone, and folic acid, but her knee issues persisted. Minimally invasive needle-knife scope therapy revealed proliferating pannus and needle-shaped crystals in the knee, indicating coexistent SNRA and atypical knee gout. After postarthroscopic surgery to remove the synovium and urate crystals, and following a tailored regimen of methotrexate, leflunomide, celecoxib, benzbromarone, and allopurinol, her knee symptoms were significantly alleviated with no recurrence observed over a period of more than one year, indicating successful management of both conditions. CONCLUSION: This study reports the case of a patient concurrently afflicted with atypical gout of the knee and SNRA and underscores the significance of minimally invasive joint techniques as effective diagnostic and therapeutic tools in the field of rheumatology and immunology.