Background and aims: The incidence of gastric MALT (mucosa-associated lymphoid tissue) lymphomas has significantly increased during the past few years. Especially when MALT lymphomas are treated conventionally, e.g., with eradication or chemotherapy, an exact classification of the lymphoma is required. The goal of this study was to compare the accuracy of endoscopic ultrasound (EUS) with other imaging techniques used in the staging of MALT lymphomas.
Patients and methods: In the setting of a prospective trial with a conservative therapeutic approach (Münster Study for GIT-NHL), altogether 44 patients diagnosed with a low-grade or high-grade malignant non-Hodgkin's lymphoma (NHL) were included in the study and classified according to their relative tumor stage using special diagnostic measures, which comprised gastroscopy (esophagogastroduodenoscopy), abdominal ultrasound, computed tomography (CT), and EUS.
Results: In 42 out of 44 patients, EUS identified the lymphoma (in two cases, final diagnosis was possible only by histologic analysis). Concerning the identification of a thickening of the stomach wall or a fusion of the layers of the stomach wall, EUS had a significantly superior score over conventional ultrasound or CT, respectively (p < 0.001). In the detection of pathologic lymph nodes, EUS was again significantly superior to ultrasound imaging. CT, however, had a statistically similar detection rate (p > 0.05). In four cases, EUS underrated a less advanced tumor stage with tumor manifestations outside the stomach (IVE). In one case, pathologic lymph nodes could be detected only with thoracic CT. In 70% of the cases, EUS imaging resulted in higher-grade tumor ranking. In 57% of cases, EUS was the only imaging technique to achieve a classification of the tumor stage at all.
Conclusion: In the diagnosis of gastric NHLs, EUS imaging is superior to conventional imaging techniques (ultrasound and CT). Therefore, the use of endoscopic ultrasound for staging can be regarded as a prerequisite for the exact tumor stage classification required in more recent conventional therapeutic approaches.