Electron dense alteration of kidney basement membranes. A renal lesion specific of a systemic disease.

Described here are the findings of a clinical, anatomic and chemical study of 40 patients having an original lesion of the basement membranes of the kidney. This lesion is characterized by an ultrastructural modification of the basement membrane substance which appears very dark (black) and homogeneous in electron micrographs. It affects the basement membranes of the glomerulus, Bowman's capsule and the renal tubules. Patients with this lesion all manifest the clinical course of a chronic enphritis and is almost invariably accompanied by proteinuria and microscopic hematuria. The disease evolves generally with intermittent episodes towards irreversible renal failure. Eight patients received kidney transplants. Study of these transplants has shown that the lesion recurs in the transplanted kidneys during the year following transplantation. Moreover, it is never found in kidneys transplanted into patients who did not have it in their own kidneys. This ultrastructural lesion can therefore be placed in the framework of a systemic disease whose etiology is not yet known. The study of these transplants also shows that the lesion can exist despite the absence of any detectable clinical or biologic signs and be well tolerated for periods which now exceed 4 years for three patients.