Thymoma and primary lymphoma of the small intestine.

A case or primary poorly differentiated lymphocytic lymphoma of the ileum in a patient previously found to have an epithelial thymoma is described. While the frequency of malignancies of many types is increased in patients with thymoma, malignant lymphomas represent the most commonly associated tumor type. Lymphomas in these patients may devleop as a result of defective immunologic surveillance, impaired immunoregulation in partially immuno-deficient hosts, or by immunostimulation. The intestinal origin of the tumor in this case suggests that it may have developed as a result of local stimulation of lymphoid tissues by an antigen or antigens present in the intestinal contents.