DETERMINATION OF A COMMON CLONAL ORIGIN OF GASTRIC AND PULMONARY MUCOSA-ASSOCIATED LYMPHOID-TISSUE LYMPHOMAS PRESENTING 5 YEARS APART

Mucosa-associated lymphoid tissue (MALT) lymphoma is often mis-diagnos ed as a benign tumor. Dissemination to other sites occurs in MALT lymp homa. We report a 60-year-old man with gastric and pulmonary tumors of MALT lymphoma which occurred 5 years apart. Initially, the gastric tu mor had been diagnosed as reactive lymphoreticular hyperplasia. To det ermine whether the two tumors arose from the same malignant clone, we amplified and sequenced the complementarity-determining region 3 of th e immunoglobulin heavy chain gene using the polymerase chain reaction (PCR). The sequences were identical except for 11-nucleotide differenc e, suggesting identical clonality.