MUCOSA-ASSOCIATED LYMPHOID-TISSUE (MALT) LYMPHOMA OF THE STOMACH PROGRESSING TO OVERT B-CELL MALIGNANCY

A 70 year old man, who underwent subtotal gastrectomy under the diagno sis of reactive lymphoid hyperplasia 6 years earlier, suffered from di ffuse large-cell-type B cell lymphoma in the remnant stomach. Retrospe ctively reviewed, the initial lesion was consistent with mucosa-associ ated lymphoid tissue (MALT) lymphoma, a low-grade B cell malignancy, b ased upon histologic, cytologic and immunohistochemical features. Both the initial and recurrent tumors revealed the phenotypes of mantle zo ne cells, DBA44-positive. It is noteworthy that the overt lymphoma cel ls retained the capacity for inducing germinal center-like nodules con sisting of LN1 and DNA7-positive cells even in the invading site. The diagnosis of reactive lymphoid hyperplasia of the stomach should be ma de after careful exclusion of the possibility of MALT lymphoma.