Further studies on the glomerular tip lesion: early and late stages and life table analysis

The glomerular tip lesion is a distinctive abnormality of the kidney associated with steroid-responsive proteinuria. It was first recognized at the stage at which there is a group of intracapillary foam cells adherent to Bowman's capsule next to the tubular origin. Late stages were investigated by studying changes to the lesion with time in seven patients known to have the foam cell stage in their first renal biopsy, and by identifying 13 patients whose biopsies had similar changes. Early stages were investigated by the study of biopsies from three patients who at some time had evidence of the tip lesion. The lesion appears to begin with leak of protein through glomeruli that are normal on light microscopy, with damage to proximal tubular epithelium. Adhesion of the glomerular tuft to Bowman's capsule and the development of foam cells then follows. The lesion is permanent but evolves either into a thin tip adhesion or into a larger area of hyalinosis and sclerosis, at first segmental and then global. The lesion can be specifically identified at all stages except the earliest. Actuarial analysis of 37 patients with the tip lesion indicated a 10-year survival of 55 per cent. The only factor identified that appeared to have an influence on survival was satisfactory control of proteinuria.