We read with interest the report by Raderer and colleagues (Gut 2006;55:616–18). The authors reported on six patients with localised gastric Helicobacter pylori negative mucosa associated lymphoid tissue (MALT) lymphoma, successfully treated with eradication therapy. They suggest that patients with early stage H pylori negative gastric MALT lymphoma might benefit from antibiotics as the sole treatment modality and, as explanation for their findings, they propose the hypothesis of a role in gastric MALT lymphoma of bacteria other than H pylori and potential immunomodulatory effects of antibiotics.

We are surprised that the authors did not consider the possibility of false negative diagnostic tests for H pylori. As no single test is accepted as the gold standard for diagnosis of H pylori infection,^1,2 they correctly used more than one: histology, urea breath test, stool antigen test, and serology. However, none of these tests has a sensitivity of 100%,^1,2 and all but serology may be affected by an altered gastric microenvironment, such as hypochlorhydria.^1,3,4 The authors give no information about previous use of antisecretory drugs in their patients but it is highly probable that patients with leading symptoms such as epigastric pain and bleeding were treated with proton pump inhibitors or H₂ antagonists before diagnosis of MALT lymphoma and this treatment may have led to negative results for …