Epstein-Barr virus-associated inflammatory pseudotumor presenting as a colonic mass.

Epstein-Barr virus (EBV)-positive inflammatory pseudotumor (IPT) commonly involves spleen and liver and has only rarely been reported in the gastrointestinal (GI) tract. The spindle cells may express myofibroblastic or follicular dendritic cell markers. We report a challenging case of EBV-positive IPT arising in the ascending colon. The lesion was composed of spindle cells positive for smooth muscle actin but negative for all follicular dendritic cell markers tested and was associated with an exuberant lymphoid proliferation containing reactive follicles, abundant plasma cells, and small lymphocytes. We further discuss pitfalls for possible misdiagnosis as ALK-positive inflammatory myofibroblastic tumor, IgG4-related disease, and peripheral T-cell lymphoma. Our case represents the first EBV-positive inflammatory pseudotumor of the GI tract in the Western literature. Awareness of this rare entity in GI tract is essential for correct diagnosis and appropriate patient management.