Focal segmental lupus nephritis.

Nineteen renal biopsies and one autopsy from fifteen patients with focal segmental lupus nephritis were examined by light and electron microscopy, and seven biopsies also by immunofluorescence microscopy. Histopathologic data were correlated with clinical course. Patients were selected on the basis of strict histologic criteria, and had to have a minimum of 2 years clinical follow-up after biopsy. All patients were treated with steroids. It could be demonstrated by light and electron microscopy that segmental lesions go through several stages of evolution, starting with mesangial proliferation, followed by necrosis and terminating as a nodule composed mainly of collagen. The necrotic lobule sometimes contains electron dense deposits, but no wire loop lesions. Prognosis was generally good with an average of 6.3 year survival of 86%. Factors contributing to outcome include number of involved glomeruli, amount of mesangial deposits outside the segmental lesions, and the presence of vasculitis. The pathogenesis of segmental lesions probably differs from that of diffuse lupus nephritis, constituting a localized reaction, independent of immune deposits in the remainder of the glomerulus, and with a considerable tendency to heal, particularly when treated with steroids.