Primary mediastinal non-Hodgkin's lymphomas: a morphologic and immunologic study of 19 cases.

Nineteen, primary, non-lymphoblastic, non-Hodgkin's lymphomas were investigated by conventional morphologic studies as well as immunologic studies using the application of a battery of monoclonal antibodies to frozen tissue sections. Seventeen of the lymphomas were diffuse large cell; one was large cell immunoblastic and one was a follicular and diffuse lymphoma of intermediate differentiation. Thirty-seven percent of the lymphomas showed prominent sclerosis, sometimes associated with the superior vena cava syndrome. Six of the cases showed evidence of immunoglobulin production with light chain restriction. Twelve additional cases were shown to be of B-cell lineage by B1/T015 expression but did not show evidence of immunoglobulin production. One case was a T-cell lymphoma of helper phenotype. Ia expression was found in 14 of 18 cases studied.