Lymphomas and pseudolymphomas of the alimentary tract. An immunohistochemical study with clinicopathologic correlations.

One hundred one lymphoproliferative lesions of the gastrointestinal tract (66 malignant lymphomas, 20 pseudolymphomas, and 5 borderline lesions) were reviewed. The pathologic features were compared to the clinical findings, with reference to differential diagnosis and prognosis. Special attention was paid to immunohistochemical features. The gross appearance was diagnostic in only a limited number of cases. Endoscopic biopsy alone was also of limited value because only a diagnosis of probability could be made in several cases. In most of them the definitive diagnosis had to be based on histologic examination of the resected specimen. Immunohistochemical examination was found to be very useful as an ancillary diagnostic technique. Malignant lymphomas displayed either cytoplasmic immunoglobulins with a monoclonal pattern (47.1 per cent) or a negative reaction, whereas the pseudolymphomas were generally characterized by polyclonal immunoglobulins. Ninety per cent of malignant lymphomas with cytoplasmic immunoglobulins contained lambda chains. The survival probability was found to be related to the size of the lesion, the depth of infiltration, and the immunohistochemical characteristics of the tumors. The histologic type of the lymphomas was of limited value as a predictor of prognosis in the present series.