Relapsing-remitting multiple sclerosis and chronic idiopathic neutropenia: a challenging combination

SUMMARY We report the challenges of treating relapsing-remitting multiple sclerosis (MS) in a 31-year-old woman with long-standing chronic idiopathic neutropenia. The treatment with the disease-modifying therapy interferon-β was significantly complicated by a further fall in her generally low neutrophil count, to values below 0.5×10 9 /l, although this recovered rapidly when the treatment was stopped. We discuss the difficulties of balancing the risk of neutropenia with a risk of MS relapse. BACKGROUND We report the case of a woman with chronic idiopathic neutropenia (CIN), who developed relapsing-remitting multiple sclerosis (MS), and whose disease-modifying treatment was complicated by her low neutrophil count. In MS, an autoimmune inflammatory response causes demyelinating lesions in the central nervous system, leading to neurodegeneration. The current first-line treatments for the relapsing-remitting type of MS are immunomodulating medications such as interferon-β (BIFN), which aim to reduce the frequency of relapses. CIN may be caused by autoantibodies against neutrophils leading to increased neutrophil destruction and decreased blood neutrophil numbers, yet patients usually remain asymptomatic. 1 It has previously been associated with MS in one published case report. 2