A 49-year-old female patient came to our clinic with increasing pain and swelling in her left wrist for two months. She was a housewife and had no known disease other than hypertension and RA. The patient was treated with a diagnosis of seronegative RA in another clinic, and she has been using methotrexate (MTX) 10 mg/week and prednisolone 5 mg/day along with RTX for two years (4 cures of RTX in total). The last infusion of RTX was administered approximately 5 months before the date she applied to our hospital. There were no signs of inflammation in her joints except the left wrist. In laboratory tests, hemogram, liver transaminases, urea, creatinine, uric acid levels and urine analysis were within normal limits. The erythrocyte sedimentation rate (ESR) was 46 mm/h and the C-reactive protein (CRP) level was 18 mg/L. Rheumatoid factor (RF), anti-cyclic citrullinated peptide antibodies (ant-CCP) and antinuclear antibodies (ANA) were negative. Chest radiography and sacroiliac joint radiography were within normal limits. Thereupon, the dose of methotrexate was increased to 15 mg/week and the dose of prednisolone to 10 mg/day. At the control two months later, there was no decrease in the patient's complaints. Moreover, redness and cutaneous fistulization developed on the radial side of the left wrist (Figure 1). The patient complained of intermittent fever and loss of appetite. Her temperature was 37.0 C, blood pressure 135/80 mmHg, and heart rate 72/minutes. Chest and abdominal examinations were normal. There was no lymphadenopathy in head and neck examination. Laboratory evaluation showed an increase in ESR (62 mm/h) and CRP (53 mg/L). There was no infiltrative lesion or pleural effusion on chest radiography. The patient was hospitalized. Blood and urine cultures were found negative. The lesion on the left wrist was debritted. Histopathologic evaluation revealed the presence of acid-fast bacilli. Polymerase chain reaction test and culture confirmed mycobacterium tuberculosis. Quadruple anti-TB treatment (ethambutol, rifampicin, pyrazinamide and isoniazid) was started. Prednisolone was terminated by reducing 2.5 mg per week. MTX and RTX were withdrawn. She was treated with 12-months course of antituberculous treatment and responded well (Figure 2). After antituberculous treatment, the patient who did not suffer pain or swelling in her other joints was not given any medication for RA. The absence of joint complaints despite not receiving immunosuppressive therapy for over a year, negative serological tests for RF, anti-CCP and ANA, and the absence of typical erosions for RA in the joints suggest that the initial diagnosis of RA may not be correct. The patient may have had viral arthritis or reactive arthritis. Less likely, the patient may be in prolonged remission.