Gastric "pseudolymphoma": a retrospective morphologic and immunophenotypic study of 97 cases

The term "pseudolymphoma" has been used to describe lymphoid 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 locations, with the stomach being one of the more common sites. In spite of the frequent use of this term, neither the histologic criteria nor the clinical significance of this lesion have ever been clearly defined. Since the description of mucosa-associated lymphoid tissue (MALT) and its corresponding MALT-type lymphomas, the value of the term gastric pseudolymphoma has come into question.

The authors reviewed all cases diagnosed as gastric pseudolymphomas at the Armed Forces Institute of Pathology from 1970 to 1985. This period predated the description of low grade B-cell lymphoma of MALT-type. The cases were reclassified in light of current criteria and correlated with immunohistochemical findings and follow-up information. No patients were treated with chemotherapy or radiation therapy.

Seventy-seven of 97 cases formerly diagnosed as pseudolymphoma were determined to be malignant lymphomas; the majority (51 cases) were extranodal marginal zone B-cell lymphomas (MALT-type). The remaining cases included reactive lymphoid hyperplasia associated with chronic follicular gastritis (15 cases) and atypical lymphoid infiltrates (5 cases).

Most cases previously considered to be gastric pseudolymphomas are, by current criteria, malignant lymphomas. A small proportion are benign reactive lymphoid hyperplasias. Those cases of borderline or inconclusive nature are best diagnosed as atypical lymphoid infiltrates. The term gastric pseudolymphoma should be abandoned.