The glomerular tip lesion: a distinct entity or not?

Howie and Brewer recently described a novel glomerulopathy: the glomerular tip lesion (GTL). The characteristic feature of this entity is a collection of intracapillary foam cells and marked vacuolization of the epithelial cells of the glomerular segment adjacent to the origin of the proximal tubule. Although this lesion resembles focal segmental glomerulosclerosis (FSGS), Howie and Brewer suggested that it constitutes a distinct entity, differing also clinically from FSGS, in that it would have a better response to steroid treatment. We treated five patients fulfilling the criteria of Howie and Brewer. However, neither corticosteroids (1.5 mg/kg/day for 1 month in five patients) nor cyclosporin-A (5 mg/kg/day for three months in four patients) caused a decrease in proteinuria to below 4 g/day. In two patients, renal function deteriorated and in one of them, recurrence of classical FSGS was found in the renal transplant. A sixth patient was observed in whose biopsy a combination of GTL with membranous glomerulopathy was present. We conclude that GTL is not a distinct entity and that in the clinical course and response to treatment it does not differ from FSGS.