A low-grade MALT lymphoma in the form of colonic lymphoid hyperplasia with an increased serum IgG2

Abstract

The concept of mucosa-associated lymphoid tissue (MALT) lymphoma has been verified and accepted since its original description in 1983.1-5 MALT lymphomas have favorable courses compared with nodal lymphomas.3-5 In particular, the low-grade MALT lymphomas tend to remain localized to their site of origin for long periods and seldom disseminate to the bone marrow.5 MALT lymphoma accounts for more than half of the cases of malignant lymphoma in any site of the gastrointestinal tract.2-5 MALT lymphoma appears most frequently in the stomach (66% of primary B-cell lymphoma3) where lymphoid tissue is not a normal constituent of the mucosa; that is, it is acquired.5 Malignant lymphoma of the large bowel is the least common lymphoma of the gastrointestinal tract, accounting for less than 1% of all cases of malignancy.2 Most of MALT lymphomas are unifocal, although a small proportion are multifocal.5 Here we report a case of low-grade, B-cell MALT lymphoma in the form of colonic lymphoid hyperplasia. This case showed another unique feature—an increased serum concentration of IgG2.