Glomerular tip lesions in renal biopsies with focal segmental IgM

Renal biopsies in which immunohistologic examination had shown the presence of glomerular focal segmental IgM were reviewed in order to investigate the histology and clinical course in these patients. Among 19 such biopsies, 12 had focal segmental glomerulosclerosis (FSGS), whereas seven had only so-called glomerular tip lesions (GTL). GTL also occurred moreover in four of the patients with FSGS. Clinical data suggest a somewhat milder course of disease in the seven patients with GTL as the sole lesion than in the patients of the FSGS group. The nature of GTL is at present unclear. We suggest that GTL may be an initial stage of FSGS, being a lesion that may or may not develop towards FSGS in its typical form. Regardless of its origin, attention is directed to the GTL as a characteristic histologic glomerular lesion, which may be the only significant histologic change in the renal biopsy from a patient with nephrotic syndrome or severe proteinuria.