GASTRIC PSEUDOLYMPHOMA - A RETROSPECTIVE MORPHOLOGIC AND IMMUNOPHENOTYPIC STUDY OF 97 CASES

BACKGROUND. The term ''pseudolymphoma'' has been used to describe lymp hoid lesions that show: 1) borderline features between hyperplasia and neoplasia or 2) benign tumor-like enlargement of lymphoid tissue. The term pseudolymphoma has been applied to lesions in many anatomic loca tions, with the stomach being one of the more common sites. In spite o f the frequent use of this term, neither the histologic criteria nor t he clinical significance of this lesion have ever been clearly defined . Since the description of mucosa-associated lymphoid tissue (MALT) an d its corresponding MALT-type lymphomas, the value of the term gastric pseudolymphoma has come into question. METHODS, The authors reviewed all cases diagnosed as gastric pseudolymphomas at the Armed Forces Ins titute of Pathology from 1970 to 1985. This period predated the descri ption of low grade B-cell lymphoma of MALT-type. The cases were reclas sified in light of current criteria and correlated with immunohistoche mical findings and follow-up information. No patients were treated wit h chemotherapy or radiation therapy. RESULTS, Seventy-seven of 97 case s formerly diagnosed as pseudolymphoma were determined to be malignant lymphomas; the majority (51 cases) were extranodal marginal zone B-ce ll lymphomas (MALT-type). The remaining cases included reactive lympho id hyperplasia associated with chronic follicular gastritis (15 cases) and atypical lymphoid infiltrates (5 cases). CONCLUSIONS. Most cases previously considered to be gastric pseudolymphomas are, by current cr iteria, malignant lymphomas. A small proportion are benign reactive ly mphoid hyperplasias. Those cases of borderline or inconclusive nature are best diagnosed as atypical lymphoid infiltrates. The term gastric pseudolymphoma should be abandoned. (C) 1997 American Cancer Society.