Right-sided infective endocarditis (IE) accounts for 5% to 10% of all IE. Compared with left-sided IE, antibiotic treatment is effective in about 70% of cases. The timing of surgical treatment for right-sided IE is therefor controversial. A 26-year-old woman had suffered from tricuspid valve endocarditis with DIC. There was no evidence of any previous cardiac event or dental treatment. Echocardiography showed a large vegetation attached to the anterior leaflet of tricuspid valve with moderate tricuspid regurgitation. We removed the vegetation with a part of the anterior leaflet and performed tricuspid valvuloplasty and annuloplasty. The patient had an uneventful postoperative course and received intravenous antibiotic treatment for a further 4 weeks.

Autoimmune enteropathy (AIE) is a rare disease, characterized by intractable diarrhea, villous atrophy of the small intestine, and the presence of circulating anti-enterocyte autoantibodies. Immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome, and mutations in FOXP3, which is a master gene of regulatory T cells (Tregs), are major causes of AIE. Recent studies have demonstrated that mutations in other Treg-associated genes, such as CD25 and CTLA4, show an IPEX-like phenotype. We present the case of a 13-year-old girl with CTLA4 haploinsufficiency, suffering from recurrent immune thrombocytopenic purpura and intractable diarrhea. We detected an autoantibody to the AIE-related 75 kDa antigen (AIE-75), a hallmark of the IPEX syndrome, in her serum. She responded well to a medium dose of prednisolone and a controlled dose of 6-mercaptopurine (6-MP), even after the cessation of prednisolone administration. Serum levels of the soluble interleukin-2 receptor and immunoglobulin G (IgG) were useful in monitoring disease activity during 6-MP therapy. In conclusion, autoimmune-mediated mechanisms, similar to the IPEX syndrome, may be involved in the development of enteropathy in CTLA4 haploinsufficiency. Treatment with 6-MP and monitoring of disease activity using serum levels of soluble interleukin-2 receptor and IgG is suggested for such cases.