Immunoperoxidase study on paraffin sections of gastrointestinal lymphoreticular lesions.

Seventy-five cases of lymphoreticular lesions of the gastrointestinal tract were studied by the immunoperoxidase method on paraffin sections which demonstrated cytoplasmic markers, in particular immunoglobulin (Ig) in B-lymphocytes and alpha-1-antichymotrypsin in histiocytes. There were 4 cases of benign immunoproliferative disease (IPD), 1 in the stomach, 3 in the small intestine; their reactions were polyclonal. Large cell non-Hodgkin's lymphoma was subdivided into 21 cases with IPD ("Mediterranean Abdominal Lymphoma") and 29 cases without. Eight cases of lymphoma with IPD were gastric and 13 intestinal; 7 gastric and 12 intestinal lymphomas were of B-cell origin; 1 gastric tumour was histiocytic; 1 intestinal neoplasm had no detectable marker. Sixteen cases of lymphoma without IPD were gastric and 13 intestinal; 4 gastric and 4 intestinal lymphomas were of B-cell type; 3 gastric and 2 intestinal neoplasms were histiocytic; 1 intestinal tumour was a composite of B-cells and histiocytes, in separate but contiguous foci; 9 gastric and 4 intestinal lymphomas had no identifiable marker. One of 18 cases of mixed and small cell lymphoma was accompanied by IPD. In these types of lymphoma Ig was found only in 10-30% of cells, mainly with plasmacytoid differentiation.