Reactive lymphoid hyperplasia of the stomach. An immunohistochemical study.

The surgically excised stomachs were re-examined histopathologically, and eighteen cases were placed in the category of reactive lymphoid hyperplasia (RLH). The distribution and the classes of infiltrating immunoglobulin (Ig) bearing cells were examined on lesions of RLH cases together with ten histopathologically determined malignant lymphomas (ML) of the stomach and the control stomachs. It was found that in eleven cases of RLH and one case of ML, many lymphoid cells bearing different classes of Ig were present in those lesions in an intermingled way (polyspecific group). Meanwhile, lymphoid cells in three RLH cases and two ML cases bore only a single monospecific Ig (monospecific group). In other cases, the number of Ig bearing cells were not sufficient to reach any clear conclusions (undetermined group). It was speculated that regardless of the histopathological diagnosis, the monospecific group might belong to the category of neoplasm of B cell type and the polyspecific group in the category of true reactive process. The possible histopathological criteria for differentiation of the reactive process and lymphoid neoplasm of the stomach were re-checked, and the importance of immunohistochemical study on these cases were stressed.