A case of extrapulmonary tuberculosis after use of baricitinib.

Extrapulmonary tuberculosis can occur in patients treated with Janus kinase inhibitors. We present a case of rheumatoid arthritis complicated by extrapulmonary tuberculosis following baricitinib treatment. A 45-year-old Japanese woman was diagnosed with rheumatoid arthritis at another hospital, and she subsequently started treatment with methotrexate at 6.0 mg/week and prednisolone at 3.0 mg/day at our institute. The methotrexate dose was increased to 10 mg/week, and clinical remission was achieved; however, the disease activity flared up 6 months after the initial visit. INH prophylaxis was started following positive T-SPOT® screening for tuberculosis, and baricitinib (Olumiant®) was introduced 3 weeks later because of an insufficient response to methotrexate. INH prophylaxis was continued for 6 months. Ten months after starting INH treatment, a painless mass was observed on the left side of the patient's neck. Magnetic resonance imaging showed enlarged lymph nodes with calcification. A subsequent biopsy and pathologic examination led to a diagnosis of tuberculous lymphadenitis, and the patient was started on anti-tuberculosis therapy. Ten months later, the patient was still in remission and doing well. Extrapulmonary tuberculosis can be difficult to diagnose because of inconsistent physical and laboratory findings. When treating patients with Janus kinase inhibitors, physicians should be cognisant of the potential for extrapulmonary tuberculosis to develop.