Based on a study of 26 cases and a review of the literature, lymphoid hyperplasia of the gastrointestinal tract can be categorized into four clinicopathologic groups: focal lymphoid hyperplasia of the stomach, focal lymphoid hyperplasia of the small intestine, focal lymphoid hyperplasia of the rectum, and nodular lymphoid hyperplasia of the gastrointestinal tract.
The focal lesions are single, variably circumscribed, and produce thickening of the wall of the affected part of the viscus. While a substantial number of the gastric lesions are associated with chronic peptic ulcers, ulceration is absent or insignificant in focal lesions located in the intestine. The extent of the infiltrate may range from involvement of the mucosa and submucosa only to infiltration of the full thickness of the wall.
Nodular lymphoid hyperplasia of the gastrointestinal tract produces multiple discrete mucosal nodules in a variable segment of the small intestine, large intestine, or both. Gastric involvement is rare. The lymphoid infiltrate is confined to the lamina propria and superficial submucosa. Nodular lymphoid hyperplasia is most commonly encountered incidentally during radiologic examination or at autopsy, but it also occurs in association with hypo-gammaglobulinemia, especially late-onset acquired hypogammaglobulinemia.
Lymphoid hyperplasia of the gastrointestinal tract can be distinguished from malignant lymphoma by the polymorphic nature of the infiltrate, the absence of significant cytologic atypia, and the presence of reactive follicles within the lesion.