Successful Treatment of Splenomegaly and Pancytopenia with Rituximab in a Patient with Nijmegen Breakage Syndrome

Nijmegen breakage syndrome is a rare autosomal recessive congenital disorder causing chromosomal instability, characterized by short stature, microcephaly, distinctive facial features, recurrent respiratory tract infections, an increased risk of cancer, intellectual disability, and other health problems. People with Nijmegen breakage syndrome have immunodeficiency. Some patients with ataxia telangiectasia-like syndromes (about 10%) have decreased serum IgA and IgG levels with normal or raised IgM level, a phenotype reminiscent of hyper IgM syndrome, which is due to class switch recombination defect. The case presented in this report was an eight-year-old female with related parents, who had been admitted to the hospital several times with recurrent infections (pneumonia and sinusitis). In immunological workups, she had high IgM, low IgG, and IgA levels. According to high α-fetoprotein level and her microcephaly, Nijmegen breakage syndrome was suggested. She was receiving IVIg monthly for two years, when she developed hypersplenism and pancytopenia. Her bone marrow aspiration and biopsy was reported normal twice. The patient underwent Rituximab therapy (375mg/m2) weekly for four weeks, with good response and improvement of splenomegaly and pancytopenia. Class switch recombination defects should be considered in patients with ataxia telangiectasia variants, especially when they have hyper IgM phenotype, and if they present lymphoproliferation, Rituximab therapy could be an effective treatment.