Relapsing and refractory cases of TTP like our first case have been effectively treated with rituximab, a monoclonal antibody against CD20 receptors on memory B cells.20, , , -24 Further studies are needed to delineate the role, dosing, and frequency of rituximab in TTP, including TTP-related MI. Here, MS4A1 is linked to thrombotic thrombocytopenic purpura.