Lymph node necrosis in systemic lupus erythematosus - A histopathological and immunohistochemical study of four cases

The lymph node lesions of lupus lymphadenitis are characterized by necrosis sometimes accompanied by hematoxylin bodies, but only a few immunohistolog ical analyses of this unique lesion have been reported. In this study we in vestigated the immunopathogenesis of these lesions. Lymph node specimens fr om four patients were analyzed immunohistochemically by applying recently d eveloped monoclonal antibodies to immunocompetent cells. Necrosis occupied almost the entire lymph node in two cases (extensive type), whereas small f oci of necrosis were found in the paracortex in the remaining two (localize d type). No hematoxylin body formation was detected in any of the samples. Necrosis of the small muscular arteries, arterioles and venules was seen in the necrotic areas in all four cases. In one case of the localized type, n ecrotizing angitis was seen in a few arterioles and venules in the non-necr otic area. By immunohistology, amorphous depositions of immunoglobulins and C3 were demonstrated in the walls of the arterioles and venules in two cas es. Our findings indicate that vasculitis due to local deposition of immune complexes in the blood vessels may play an important role in the pathogene sis of necrosis in lupus lymphadenitis.