Metastatic Gastric MALT Lymphoma Masquerading as Pulmonary Infiltrates, with a Dramatic Response to Chemotherapy

In 1983, Isaacson and Wright described the entity mucosaassociated lymphoid tissue lymphoma [1]. It is a type of nonHodgkin’s lymphoma, now classified as an extranodal marginal zone B cell lymphoma [2]. By definition, a low-grade lymphoma, mucosa-associated lymphoid tissue (MALT) lymphoma is thought to develop as a result of chronic antigenic stimulation. Epidemiologic models indicate that over 90 % of gastric MALT lymphomas arise in the presence of Helicobacter pylori infection and that eradication of H. pylori infection leads to endoscopic and histologic remissions in the majority of those cases [3, 4]. Autoimmune diseases may also create a setting of chronic inflammation and antigenic stimulation leading to MALT lymphoma [5]. It is also postulated that elements of the innate immune system play a role in the defense against lymphoproliferative diseases, and particularly, natural killer cell dysfunction is seen in high-grade nonHodgkin’s lymphomas [6]. Genetic abnormalities, notably certain high-risk chromosomal translocations such as t(11;18), t(1;14), and t(14;18), to name a few, have also been implicated as a cause of antigenindependent proliferation, particularly in cases not associated with or not responsive to H. pylori eradication [7]. On immunophenotype analysis, MALT lymphoma demonstrates B cell markers, CD19, CD20, and CD45 [8]. Predominantly found in gastric tissue, it can virtually arise in any epithelial tissue. Some sites worth mentioning include the lung, eye, skin, salivary glands, and breast. Systemic screening is therefore essential when MALT lymphoma is suspected. A good history and physical exam are key, followed by definitive histopathologic diagnosis via biopsies. Endoscopic biopsies for gastric MALT lymphoma are diagnostic in more than 75 % of the patients and should include evaluation for H. pylori infection [9]. Here, we report a case of metastatic gastric MALT lymphoma with a dramatic response to treatment.