Lymphomatoid granulomatosis of the lung. An immunohistochemical study

11 cases of lymphomatoid granulomatosis, selected because of available immunological data, are presented. The evolution of these cases has been studied by repeated biopsies and/or eventual autopsy using immunohistochemical methods. The follow-up period ranged between 1 and 144 months. All cases but 2 died of a direct or indirect consequence of their disease; 1 of the 2 patients still alive presented a recurrence after 3 years. The histological changes which occurred in the infiltrates argue in favor of a neoplastic transformation of the disease after a variable lapse in time, in spite of treatment. The death is due either directly to the neoplasia or to an infectious complication enhanced by the treatment. The malignancy which follows is generally an immunoblastic lymphoma. Immunohistochemical studies show that the infiltrates are polyclonal in the early phases of the disease and become monoclonal in the late stages. In many cases the transformation into a 'B' immunoblastic lymphoma is marked by the appearance of a monoclonal gammopathy. These immunohistochemical studies support the opinion that the lymphomatoid granulomatosis is a peculiar situation between a reactive and neoplastic state but which evolves eventually into the latter.