Colonic obstruction induced by plasma cell granuloma of the transverse colon: report of a case.

Plasma cell granuloma is mainly composed of reactive plasma cell proliferation, the origin of which is uncertain. Immunohistochemically, the plasma cells are characterized by a polyclonal nature, and must be distinguished from plasmacytoma which displays a monoclonal nature. This tumor is most commonly found in the lung and bronchus, but has rarely been described in the alimentary tract. We report herein a case of plasma cell granuloma of the transverse colon. A 71-year-old woman was admitted for lower abdominal pain with severe inflammation and anemia. Ultrasound examination and computed tomography showed an abdominal tumor. Barium enema revealed the tumor to be located in the transverse colon causing colonic obstruction. The resected tumor was spherical and mainly spread in the submucosal layer. Microscopically, the tumor consisted of severe infiltration of mature plasma cells within the spindle-shaped myofibroblasts. Immunohistochemical studies showed IgA, IgG, IgM, and kappa and lambda chains, and revealed a polyclonal nature of the plasma cells. Thus, a pathological diagnosis of plasma cell granuloma affecting the transverse colon was made. To the best of our knowledge, this is the first report of successful surgical resection of plasma cell granuloma of the colon.