A case in which baricitinib was effective for both rheumatoid arthritis and essential thrombocythemia.

We experienced a case of rheumatoid arthritis and JAK2V617F mutation-positive essential thrombocythemia treated with baricitinib. The patient was a 72-year-old male. He was diagnosed with rheumatoid arthritis at a local clinic in April 2018. Methotrexate (MTX) was started and the dose was increased to 16 mg/week. In October of the same year, anaemia was observed and MTX was reduced, but anaemia progressed. Blood tests showed pancytopenia, and he was referred to Rheumatology on suspicion of drug-induced pancytopenia. Pancytopenia improved with discontinuation of MTX and administration of folic acid. His platelet count was markedly increased to 1,400,000/µl at one point, decreased to 400,000/µl, and then gradually increased to 700,000-1,000,000/µl. Despite taking an antiplatelet drug, he developed cerebral infarction in June 2019. The JAK2V617F mutation was noted, and he was diagnosed with essential thrombocythemia. Hydroxycarbamide was started, but the effect was insufficient. Baricitinib, a JAK1/2 inhibitor indicated for rheumatoid arthritis, was started in August with the expectation that it would also be effective for essential thrombocythemia. The platelet count decreased to ∼400,000-600,000 cells/µl, and a decrease in the C-reactive protein level and the improvement of arthritis were noted. We report this case because it is considered to be a valuable case, suggesting that baricitinib may be effective for essential thrombocythemia.

A Case of Rapidly Progressing Hepatocellular Carcinoma after Administration of JAK Inhibitors to Treat Rheumatoid Arthritis.

We report a case of rapidly progressing hepatocellular carcinoma after administration of Janus kinase (JAK) inhibitors to treat rheumatoid arthritis. A 76-year-old man was referred to our Department for pain in multiple joints and was diagnosed with rheumatoid arthritis. Blood tests revealed elevated hepatobiliary enzymes, but various tests revealed no signs suggestive of malignancy. He took baricitinib for 2 months followed by tofacitinib for 4 months. After that, he was diagnosed with hepatocellular carcinoma based on imaging findings and elevated tumor markers. This case showed the possibility of a causal relationship between JAK inhibitors and malignancy.

Successful Treatment of Systemic Sclerosis-related Pericarditis with Mycophenolate Mofetil and Low-dose Prednisolone.

We herein report a case of systemic sclerosis (SSc)-related pericarditis successfully treated with mycophenolate mofetil (MMF) and low-dose prednisolone (PSL). The patient was a 72-year-old woman with anti-centromere antibody. Her clinical manifestations were Raynaud phenomenon, bilateral pleural effusion, pericardial effusion and skin tightness. Based on the findings of exudative pericardial effusion with the absence of pulmonary arterial hypertension from the results of the cardiac catheter and pericardiocentesis, she was diagnosed with SSc-related pericarditis and treated with PSL10 mg and MMF 1 g per day, leading to the complete resolution of pericarditis. These findings suggested that MMF and low-dose PSL were effective for SSc-related pericarditis.