Primary gastric lymphoma (lymphoma that originates in the stomach itself) is an uncommon condition, accounting for less than 15% of gastric malignancies and about 2% of all lymphomas. However, the stomach is a very common extranodal site for lymphomas (lymphomas originate elsewhere and metastasise to the stomach). It is also the most common source of lymphomas in the gastrointestinal tract.
Distinguishing poorly differentiated gastric lymphoma from adenocarcinoma is essential because the prognosis and modalities of treatment differ significantly.
Other lymphomas involving the stomach include mantle cell lymphoma and T-cell lymphomas which may be associated with enteropathy; the latter usually occur in the small bowel but have been reported in the stomach.
The diagnosis is typically made by biopsy at the time of gastroscopy. Several endoscopic findings have been reported, including solitary ulcers, thickened gastric folds, mass lesions and nodules. As there may be infiltration of the submucosa, larger biopsy forceps, endoscopic ultrasound guided biopsy, endoscopic submucosal resection, or laparotomy may be required to obtain tissue.
Imaging investigations including CT scans or endoscopic ultrasound are useful to stage disease. Hematological parameters are usually checked to assist with staging and to exclude concomitant leukemia. An elevated LDH level may be suggestive of lymphoma.
Antibiotic treatment to eradicate H. pylori is indicated as first line therapy for . About 80% of MALT lymphomas completely regress with eradication therapy. Radiation treatment for H. pylori–negative gastric malt lymphoma, has a high success rate, 90% or better after 5 years. Second line therapy for MALT lymphomas is usually chemotherapy with a single agent, and complete response rates of greater than 70% have been reported.
Subtotal gastrectomy, with post-operative chemotherapy is undertaken in refractory cases, or in the setting of complications, including gastric outlet obstruction.
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