Immunohistochemistry of primary gastrointestinal lymphomas: a study of 76 cases.

A retrospective study of 76 primary gastrointestinal lymphomas utilizing an avidin: biotinylated horseradish peroxidase complex (ABC) technique demonstrated 22 B-cell lymphomas, including two associated with alpha-heavy chain disease. Seven cases were classified as true histiocytic lymphomas based on a positive reaction for one or more of three histiocytic enzyme markers utilized, predominantly alpha-1-antitrypsin and alpha-1-antichymotrypsin. However, in 20 cases, an intense admixture of reactive histiocytes was noted and these cells stained preferentially for the enzyme, lysozyme. Twenty cases, which stained for both kappa and lambda light chains and positively or negatively for albumin, could not be classified and 27 cases failed to stain with any of the antisera utilized.