Focal segmental glomerular tip lesions with IgM. A case report.

In a 59-year-old man with nephrotic syndrome, immunohistochemical examination of a renal biopsy revealed exudations of IgM localized to peripheral segments of the tufts in some glomeruli. This pattern is known so far to occur only in some cases of focal segmental glomerulosclerosis (FSGS). In this patient, however, no histological criteria of FSGS were present, nor was the clinical course typical of this disease, being characterized by changing reactions to steroid therapy. The patient was therefore considered to suffer from a disease different from FSGS. The histological lesion may possibly be identical with what has recently been described as the glomerular "tip lesion".