BackgroundEpstein–Barr virus-positive mucocutaneous ulcer (EBV-MCU) is a new category of mature B-cell neoplasms. Ulcers occur in the oropharyngeal mucosa, skin, and gastrointestinal tract. The onset of EBV-MCU is suggested to be related to the decreased immunity of the patient, the causes of which include the use of immunosuppressive agents and aging. EBV-MCU may regress spontaneously and it often has a benign course after the dose reduction or discontinuation of immunosuppressive agents or during follow-up. Here, we report the case of a patient who required surgical resection for the intestinal obstruction arising from EBV-MCU.Case presentationA Japanese elderly male visited our hospital with chief complaints of a palpable mass and dull pain in the left upper quadrant, loss of appetite, and weight loss. Although abdominal computed tomography and total colonoscopy (TCS) revealed a tumor with circumferential ulcer in the transverse colon, histopathological analysis of a biopsy specimen of this lesion showed only nonspecific inflammation. Because the tumor spontaneously regressed during the time he underwent tests to obtain a second opinion from another hospital, TCS was reperformed on the patient. TCS revealed that the tumor decreased in size and the inflammatory changes in the surrounding mucosa tended to improve; however, tightening of the surrounding mucosa due to scarring was observed. Another histopathological analysis of a biopsy specimen showed widespread erosion of the mucosa and the formation of granulation tissue with marked infiltration of various inflammatory cells into the mucosal tissue of the large intestine. Moreover, some of the B-lymphocyte antigen CD20-positive B cells were also positive for EBV-encoded small RNA-1, suggesting the possibility of EBV-MCU. Later, the tumor developed into an intestinal obstruction; thus, the transverse colon was resected. Histopathological analysis of the resected specimen demonstrated scattered Hodgkin and Reed–Sternberg-like multinucleated large B cells in addition to EBER-1-positive cells. The patient was finally diagnosed as having EBV-MCU.ConclusionsThis is the first report of a case of EBV-MCU that developed into an intestinal obstruction requiring surgical resection. It is necessary to consider the possibility of EBV-MCU when examining an ulcerative or tumorous lesion in the gastrointestinal tract.