Late-onset neutropenia after rituximab therapy in patients with autoimmune thrombotic and hemostatic disorders: a single center analysis.

: Autoimmune thrombotic and hemostatic disorders, caused by autoantibodies against various factors regulating thrombosis and hemostasis, are rare. Rituximab (RTX) is on occasion used for treating these disorders. Late-onset neutropenia (LON) has been described as a side effect of RTX treatment for patients with hemato-oncological and/or rheumatological diseases but not for those with autoimmune thrombotic and hemostatic disorders. Eleven patients with autoimmune thrombotic and hemostatic disorders received RTX in our institution. Four of these 11 cases (36.4%) developed LON after a median 72.6 days of RTX administration (range 43-122). Three cases required G-CSF, but no severe infections developed.