A 75-year-old man was diagnosed as having RA 2 years ago because of polyarthralgia and increases in inflammatory reactions, rheumatoid factor and anti-cyclic citrullinated peptide antibody. At first, prednisolone (PSL) was prescribed at 5 mg per day, and salazosulfapyridine and methotrexate were added shortly thereafter because his RA was not under good control. After half a year, abatacept was also added because the above-mentioned medicines were still not enough to control the RA. After the addition of abatacept, his RA had been well controlled.
Two years later, he complained of a cough and slight fever. Laboratory data indicated increased inflammatory reaction, and a chest X-ray and computed tomography (CT) scan revealed consolidation in the right upper field lung (Fig. 1A and B). The patient's previous physician suspected bacterial pneumonia, discontinued the abatacept, and prescribed new quinolone antibiotics. However, the patient's pulmonary symptoms and laboratory data did not improve, and his RA was getting worse. Thereafter, Mycobacterium tuberculosis was confirmed by polymerase chain reaction and culture of his sputum. The isolated M. tuberculosis was susceptible to all anti-TB drugs. The result of a T-SPOT  TB test was indeterminable, and his C-reactive protein and matrix metalloproteinase 3 levels were elevated (Table 1).
After the diagnosis of TB, an anti-TB regimen comprising isoniazid, rifabutin, ethambutol and pyrazinamide was initiated. His cough improved although he still had a slight fever after the anti-TB regimen. On the 21st day of therapy, he experienced breathlessness, and oxygen at 2 L was necessary to maintain his blood oxygen level. A chest X-ray and CT scan showed progression of consolidation in the right upper field lung and new consolidation in the left upper field lung (Fig. 2A and B). A paradoxical reaction was suspected because consolidation in the pre-existing lesions had worsened and a new lesion appeared even though his clinical symptoms had improved with the anti-TB regimen. We added steroid pulse therapy (methylprednisolone at a daily dose of 1000 mg for 3 days) to the ongoing anti-TB therapy, after which his chest X-ray, oxygen saturation and RA symptoms immediately improved. After steroid pulse therapy, PSL 60 mg per day was used as steroid maintenance therapy. After steroid therapy for one month, almost all consolidations in the bilateral upper lung fields had disappeared (Fig. 3). We began to gradually taper the dose of PSL every week because his clinical course was uneventful.
When the PSL was reduced to 15 mg per day, he experienced exacerbation of left knee joint pain, and was no longer able to walk. His RA was thought to have recurred, so we increased the PSL to 20 mg per day. However, his symptoms were little improved. Because a high dose of PSL was needed to control his RA, we implemented a policy of re-administering abatacept to promote RA control.
After re-administration of abatacept, his symptoms improved gradually, and we succeeded in reducing the PSL by 2.5 mg every two weeks. He was discharged under good control of RA with PSL at 10 mg per day and has continued to maintain a good clinical course after discharge (Fig. 4).
With regard to TB, culture of his sputum was positive only once after admission. However, liver function disorder, a drug rash and bleary eyes occurred as adverse events. The anti-TB regimen was therefore changed to the combination of isoniazid, rifampicin and levofloxacin, with the ethambutol and pyrazinamide eliminated (Fig. 4). He is currently being treated with anti-TB therapy without relapse of his M. tuberculosis infection.
(B) Chest computed tomography shows the spread of consolidation in the bilateral lung lobes.