[Multiple microthromboses with autoimmune hemolytic anemia after BNT162b2 mRNA vaccination].

A 68-year-old man was referred to our hospital with dizziness and mild fever one week after receiving the second dose of the COVID-19 mRNA vaccine (BNT162b2). Laboratory tests showed hemolytic anemia and a positive direct Coombs test, and he was diagnosed with autoimmune hemolytic anemia (AIHA). On admission, the patient had impaired consciousness with auditory hallucinations, and a head MRI scan showed multiple high-signal areas on diffusion-weighted imaging, suggesting multiple recent infarctions. Echocardiography also showed decreased wall motion in the inferior and posterior walls. A skin biopsy to investigate the cause revealed many platelets and fibrin thrombi in the capillaries and small veins, which was considered the cause of the organ damage. After starting prednisolone (1 mg/kg) for AIHA, hemolytic anemia as well as impaired consciousness, and decreased wall motion rapidly improved. Microthrombosis after BNT162b2 mRNA vaccination is rare, and autoimmune abnormalities appeared to contribute to onset in this case.

[An elderly patient with lymphoplasmacytic lymphoma successfully treated with low-dose tirabrutinib].

A 93-year-old woman was diagnosed with lymphoplasmacytic lymphoma (LPL) with circulating tumor cells in her peripheral blood after presenting with anemia. LPL progressed eight months later, with anemia worsening and tumor cells increasing to 66% of leukocytes. She began tirabrutinib at a low dose (80 mg daily: 17% of the standard dose) because she preferred to maintain her quality of life (QOL). Within three weeks, she was free of transfusion dependency and had a partial response with the disappearance of peripheral tumor cells. The dosage of tirabrutinib was increased to 240 mg daily because it was well tolerated. She has been on the treatment for 13 months with no adverse effects. Tirabrutinib, a highly selective Bruton's tyrosine kinase inhibitor, has been reported to have promising efficacy for LPL, but it also has a high incidence of dermatological toxicity, which may impair QOL. Low-dose tirabrutinib initiation may be effective and assist elderly patients with LPL in maintaining their QOL.