A 64-year-old man comes to the office due to persistent upper abdominal pain and nausea. He experienced epigastric discomfort after taking ibuprofen for an ankle injury several months ago. He stopped taking ibuprofen and took omeprazole for 2 weeks, which provided some relief. However, when he stopped omeprazole his pain started again and has progressively worsened. The patient also has occasional nausea and loss of appetite. He has a remote history of tobacco use but no other medical problems. He immigrated to the United States from Laos 20 years ago. Physical examination reveals minimal epigastric tenderness. Upper gastrointestinal endoscopy demonstrates mild gastric erythema and a 4-cm mass in the body of the stomach along the greater curvature. Several biopsies are obtained and histopathology is consistent with low-grade lymphoma arising from the mucosa-associated lymphoid tissue (MALT). Imaging studies reveal no lymphadenopathy or metastatic disease. Which of the following is most likely involved in the pathogenesis of this patient's current condition?

Question

A 64-year-old man comes to the office due to persistent upper abdominal pain and nausea.  He experienced epigastric discomfort after taking ibuprofen for an ankle injury several months ago.  He stopped taking ibuprofen and took omeprazole for 2 weeks, which provided some relief.  However, when he stopped omeprazole his pain started again and has progressively worsened.  The patient also has occasional nausea and loss of appetite.  He has a remote history of tobacco use but no other medical problems.  He immigrated to the United States from Laos 20 years ago.  Physical examination reveals minimal epigastric tenderness.  Upper gastrointestinal endoscopy demonstrates mild gastric erythema and a 4-cm mass in the body of the stomach along the greater curvature.  Several biopsies are obtained and histopathology is consistent with low-grade lymphoma arising from the mucosa-associated lymphoid tissue (MALT).  Imaging studies reveal no lymphadenopathy or metastatic disease.  Which of the following is most likely involved in the pathogenesis of this patient's current condition?

Quizplus · Accepted Answer

Helicobacter pylori infection plays a critical role in the pathogenesis of extranodal marginal zone B cell lymphomas (low-grade B cell lymphoma of mucosa-associated lymphoid tissue [MALT]) of the stomach. It is present in 90% of patients with tumors. Chronic inflammation from H pylori infection results in stimulation of large numbers of antigen-dependent B and T cells in the gastric lamina. The chronic activation and proliferation eventually results in a monoclonal population of B cells that no longer depends on normal stimulatory pathways for growth. B and T cells in the gastric lamina As a result, all patients with MALT lymphomas should be tested for H pylori infection, and patients with a positive result who have early-stage MALT lymphoma should undergo H pylori eradication therapy (eg, quadruple therapy). The majority of patients achieve complete remission with antibiotic treatment. Patients with more advanced malignancies or with H pylori-negative tumors should be considered for radiation therapy, immunotherapy (eg, rituximab), or single-agent chemotherapy. (Choices A, D, and F) Various environmental factors such as cigarette smoking, high salt intake, and consumption of N-nitroso compounds (found in processed meats and cheeses) are associated with increased risk for gastric adenocarcinoma but not MALT lymphomas. (Choice B) Nonsteroidal anti-inflammatory drugs are not associated with an increased risk of MALT lymphoma and appear to be a protective factor for gastric adenocarcinoma, with longer use associated with greater reductions in risk. (Choice E) Although various autoimmune disorders such as Sjögren syndrome and Hashimoto thyroiditis are associated with an increased risk for MALT lymphomas, pernicious anemia is not. Instead, pernicious anemia is related to an increased risk of gastric adenocarcinoma and gastric carcinoid tumors. Educational objective: Helicobacter pylori infection plays a critical role in the pathogenesis of extranodal marginal zone B cell lymphomas (low-grade B cell lymphoma of mucosa-associated lymphoid tissue [MALT]) of the stomach. All patients with MALT lymphomas should be tested for H pylori infection, and those with a positive result and early-stage MALT lymphoma should undergo H pylori eradication therapy (eg, quadruple therapy). References: Gastric mucosa-associated lymphoid tissue lymphoma and Helicobacter pylori infection: a review of current diagnosis and management. (http://www.ncbi.nlm.nih.gov/pubmed/27468353) Gastric MALT lymphoma: old and new insights. (http://www.ncbi.nlm.nih.gov/pubmed/24714739)

A 64-Year-Old Man Comes to the Office Due to Persistent