Primary B-cell gastric lymphoma.

A detailed clinicopathologic and immunocytochemical study was performed in 12 cases of primary gastric lymphoma in which fresh tissue was available for study. The patients ranged in age from 18 to 76 years; persistent epigastric symptoms had led to endoscopy (often on multiple occasions) and biopsy in each case. The endoscopic appearances rarely suggested malignancy. The histologic appearances of the gastrectomy specimens covered a spectrum, from changes normally considered characteristic of "pseudolymphoma" to those of florid malignant lymphoma, with evidence of extragastric spread in four cases. Formation of follicular centers characterized each case, and diffuse interfollicular infiltrates of centrocyte-like cells were also present. Plasma cells were also consistently present. Immunocytochemical studies showed the same light chain restriction of follicular center cells and centrocyte-like cells in all cases and of plasma cells in five cases. Follicular center cells and centrocyte-like cells were otherwise phenotypically distinct. This study yielded criteria for the objective diagnosis of gastric B-cell lymphoma in biopsy and resection specimens; the results suggest that the term pseudolymphoma should no longer be used.