An unusual cause of recurrent pneumonia in adults

Selective IgM deficiency is a rare primary immunodeficiency defined as isolated low levels of IgM. It presents with recurrent infections and has been described as first presenting in adulthood with recurrent respiratory tract infections. Unlike its better known counterpart of IgA deficiency, this particular immunodeficiency is often overlooked. We present a case of selective IgM deficiency who presented with recurrent respiratory infections.