Mesangial electron-dense deposits in membranous nephropathy.

In the absence of lupus, mesangial electron-dense deposits in membranous nephropathy are thought to be uncommon. In this study 18 renal biopsies of 16 cases seen over a 2-year period were evaluated by light and electron microscopy and immunofluorescence, directing particular attention to the mesangium. Lupus had been excluded in every instance by the usual serologic tests. In seven of the 18 biopsies, mesangial electron-dense deposits were found. Clinically, almost all of these patients were characterized by atypical features: five patients had underlying diseases which have been associated with membranous nephropathy (renal vein thrombosis, epidermoid carcinoma of the lung, SH-antigenemia, rheumatic heart disease and penicillamine therapy); there was one instance of spontaneous remission and another patient who progressed to terminal renal failure in less than 2 years. The results suggest that the presence of mesangial deposits in membranous nephropathy may be more common than has previously been suspected. This finding is not necessarily associated with systemic lupus erythematosus and may indicate an unusual or atypical form of membranous nephropathy.