Hyper-IgM1 syndrome with interstitial pneumonia and diarrhea caused by coxsackievirus B4 in a 3-month-old infant.

Background Hyper-IgM1 syndrome is a rare genetic primary immunodeficiency disease caused by mutations of the CD40 ligand gene. It is characterized by normal or elevated levels of IgM and markedly decreased serum IgG, IgA, and IgE levels. Patients with this syndrome often easily develop infections. During the past decade, it has become clear that enteroviral infections may also occur as a manifestation of hyper-IgM1 syndrome. Objective To report a case of hyper-IgM1 syndrome in a 3-month-old boy who had interstitial pneumonia and intractable diarrhea. Methods Chest radiography, bronchoscopy, immune studies, and open lung biopsy were performed. Results Chest radiography revealed diffuse bilateral infiltrates. Immune studies revealed the following proportions of lymphocyte markers: CD3, 5,976/μL; CD4, 5,015/μL; CD8, 866/μL; CD19, 1,325/μL; CD16 + 56, 935/μL; and active T cells, 225/μL. The IgG level was 190 mg/dL; IgA, 2 mg/dL; IgM, 34 mg/dL; IgE, 1 IU/dL; and CH 50 , 23.8/mL. CD40L expression was less than 1%, and a Tyr 169 Asn (t526a) mutation in the exon 5 tumor necrosis factor domain of the CD40L gene was found. The patient was treated with intravenous immunoglobulin and had a dramatic improvement in symptoms. Open lung biopsy failed to demonstrate pneumocystis, and there was no evidence of cryptosporidium in the stool. However, coxsackievirus B4 was isolated by viral throat culture. Conclusion Interstitial pneumonia and diarrhea caused by coxsackievirus B4 may be a complication of hyper-IgM1 syndrome.