Primary gastric lymphoma is the most common type of extranodal lymphoma and accounts for 3% to 5% of all malignant gastric tumors, ranking second only to gastric cancer. The exact cause of the disease remains unclear; however, recent studies have identified a significant association between Helicobacter pylori (HP) infection and the development of mucosa-associated lymphoid tissue (MALT) lymphoma in the stomach. HP presence has been detected in the gastric mucosa of nearly all patients with gastric lymphoma.
Pathology
More than 95% of primary malignant gastric lymphomas are non-Hodgkin lymphomas, and the predominant histological type involves B lymphocytes. The lesions originate from mucosa-associated lymphoid tissue, forming lymphoid follicles in the submucosa, which progressively spread to adjacent tissues and invade the full thickness of the gastric wall. Macroscopic examination reveals thickened and raised mucosa with an intact surface; however, disease progression may lead to ulcer formation, focal infiltration of the gastric wall, or linitis plastica-like changes. Severe cases may result in bleeding or perforation. The lesions may occur in any part of the stomach but are most commonly found on the posterior wall and lesser curvature of the distal two-thirds of the stomach. Malignant gastric lymphomas predominantly spread via lymphatic metastasis.
Clinical Manifestations
Early-stage symptoms are nonspecific and are often misdiagnosed as gastric ulcer or gastric cancer. The most common symptom is epigastric pain, which may be accompanied by nausea, vomiting, weight loss, gastrointestinal bleeding, anemia, and other complaints. A palpable epigastric mass may be detected in some patients, while a minority may experience irregular fever.
Diagnosis
Gastroscopy typically reveals mucosal elevations, ulcers, thickened coarse folds with cobblestone-like changes, and submucosal nodules or masses. As malignant gastric lymphomas often grow within the submucosal layer, superficial biopsy sampling may be insufficient for an accurate diagnosis. Endoscopic ultrasonography (EUS) can provide detailed information regarding the depth of gastric wall invasion and lymph node involvement. Combining EUS assessments with deep biopsies from multiple sites during endoscopy can significantly improve diagnostic accuracy. Computed tomography (CT) imaging often reveals gastric wall thickening and provides insights into whether adjacent organs such as the liver or spleen are affected, as well as the status of mediastinal and abdominal lymph nodes, assisting in the differentiation of primary and secondary gastric lymphomas.
Treatment
Early-stage, low-grade MALT lymphomas of the stomach can be treated with anti-Helicobacter pylori therapy. After eradication of HP, tumor regression typically occurs within 4 to 6 months, with response rates of 60% to 70%. Cases resistant to antibiotic therapy may harbor highly malignant lesions and might benefit from radiotherapy or chemotherapy. The CHOP regimen is commonly used for chemotherapy, as gastric lymphoma generally responds well to such treatments, significantly improving the five-year survival rate. Surgical treatment not only helps determine the clinical and pathological stage but also offers a chance for cure in patients with localized early-stage disease.