Hyper-IgM Syndrome Complicated with Interstitial Pneumonia and Peritonitis

Hyper-IgM syndrome (HIM) is a rare disorder resulting from mutation in the CD40 ligand(CD40L) gene. This defect is associated with normal or elevated serum level of IgM andwith low to undetectable levels of serum IgG, IgA, IgE. This case of HIM with CD40L deficiencywas proven by flow cytometry but initially presented as interstitial pneumonia.Pneumocystis carinii pneumonia was highly suggested. After intravenous immunoglobulinand trimethoprim-sulfamethoxazole treatment, his lung condition improved. However, peritonitisdeveloped and surgical intervention was performed. Ileum perforation and intestinallymphoproliferation from a pathologic specimen were noted. Although peritonitis isextremely rare in patients with HIM, this report indicates that peritonitis which results fromintestinal lymphoproliferation may be a manifestation of HIM.