Symptomatic Primary Selective IgM Immunodeficiency - B Lymphoid Cell Defect in Adult Man with Secondary HLH Syndrome.

Selective immunoglobulin M deficiency(sIgMD) is a rare form of dysgammaglobulinaemia characterized by an isolated low level of serum immunoglobulin M (IgM). It was an incidence of less than 0.03% in the general population and 1% in hospitalized patients. sIgMD may occur as a primary or secondary condition. sIgMD is much more common than primary .Hemophagocytic lymphohistiocytosis (HLH) is also a rare but potentially fatal disease of normal but overactive histiocytes and lymphocytes and can be primary or secondary, characterized by the overwhelming activation of normal T lymphocytes and macrophages, invariably leading to clinical and hematologic alterations. We report an adult case of primary sIgMD with absent B lymphoid cells and secondary HLH syndrome who presented with recurrent infections, fever and pancytopenia.