RESUMO
The hyper-IgM syndrome is a rare immunodeficiency disease in which the ability of B cells to switch immunoglobulin production from IgM to IgG, IgA and IgE is defective. The deficiency of IgG and IgA leads to recurrent infections of the respiratory tract, but some patients are susceptible to infection with opportunistic microorganisms, such as Cryptococcus neoformans, and also are prone to neutropenia and mucocutaneous ulcerations. We report a case of a two-year-old boy that was given the diagnosis of the hyper-IgM syndrome on the basis of low serum concentrations of IgG and IgA and high serum levels of IgM associated with C. neoformans infection, neutropenia and mucocutaneous ulcerations. Intravenous immune globulin improves dramatically the disorder, including neutropenia. To date, periodical infusion of immune globulin has prevented the development of serious infections.
