Chronic Severe Neutropenia Associated With Intravenous Immunoglobulin for Multifocal Motor Neuropathy

Intravenous immunoglobulin (IVIG) is an immunomodulatory therapy derived from pooled donor immunoglobulins and used for treatment of various autoimmune conditions. Here we report the diagnosis and management of IVIG-induced chronic severe neutropenia with absolute neutrophil count <0.5×10³/µL in a patient with multifocal motor neuropathy. Serial blood count showed a cyclical pattern of neutropenia: worsening 24-48 h post-IVIG, then gradually improving before the next infusion. IVIG-induced neutropenia is rare, with previous reports of predominantly mild transient neutropenia. Our case describes chronic severe neutropenia that developed years after starting IVIG. We summarize available evidence and management strategies for IVIG-associated neutropenia.