Lymph node reactions to cancer.

Histological, histomorphometrical and histochemical data on the response of regional lymph nodes to tumor development, as recorded in experimental and clinical studies, were coordinated and supplemented by recent findings in experimentally induced autochthonous carcinomas in the rat gastrointestinal tract. The attempted correlation led to the definition of several prognostic parameters: 1) The development of germinal centers and the plasmocytic reaction in tumor draining nodes are morphological expressions of active humoral immune responses that may be specifically directed against the tumor. These reactions attain their maximum usually during late stages of tumor development. Their incidence and prognostic significance may vary depending upon the stage and the type of tumor. 2) Sinus histiocytosis is an immunologically nonspecific lymph node response with debatable prognostic significance. 3) Granulomatous sarcoid-like lesions may be understood as signs of an immunologically mediated antitumor response of macrophages activated by T lymphocytes. They are indicative of a favorable prognosis. 4) Paracortical hyperplasia, characterized by an increased population of lymphocytes and eventually immunoblasts, is an expression of an active T-cell reaction. This reaction occurs typically during early stages of experimental tumors. Correspondingly, it is of favorable prognostic significance in human tumors. 5) Lymphocytic depletion and nodular alteration of T-cell areas, with increased histiocytic infiltration, are reactions most often seen in the draining nodes of an advanced tumor. Both seem to coincide with depression of the cell-mediated immune reactivity. The present assessment of the reactive behavior of diverse lymph node compartments may serve as a first pointer to the proposed histologic immunostaging of malignant tumors.