Primary gastrointestinal lymphoma: spectrum of imaging findings with pathologic correlation.

Gastrointestinal lymphoma is an uncommon disease but is the most frequently occurring extranodal lymphoma and is almost exclusively of non-Hodgkin type. Primary gastrointestinal lymphoma most commonly involves the stomach but can involve any part of the gastrointestinal tract from the esophagus to the rectum. Risk factors for the development of gastrointestinal lymphoma include Helicobacter pylori infection, immunosuppression after solid organ transplantation, celiac disease, inflammatory bowel disease, and human immunodeficiency virus infection. Although gastrointestinal lymphoma has a wide variety of imaging appearances and definitive diagnosis relies on histopathologic analysis, certain findings (eg, a bulky mass or diffuse infiltration with preservation of fat planes and no obstruction, multiple site involvement, associated bulky lymphadenopathy) can strongly suggest the diagnosis. Imaging also plays an important role in the detection of complications such as perforation, obstruction, and fistulization. The most commonly used imaging modalities are barium examination and computed tomography (CT). These modalities are complementary, although CT provides a better overall assessment of the disease stage. (c) RSNA, 2007.