Tip Lesion Variant of Focal Segmental Glomerulosclerosis in Familial Relapsing Polychondritis.

Relapsing polychondritis (RP) is a rare autoimmune disorder with minimal reported renal involvement. We describe the first case of tip lesion variant of focal segmental glomerulosclerosis (FSGS) in a 60-year-old male with familial RP. The patient initially presented with nephrotic syndrome concomitant with RP, which was diagnosed 17 years ago; renal biopsy revealed minimal change disease at that time. Over the subsequent 17 years, he experienced four RP flares without nephrotic syndrome recurrence until his recent presentation with severe nephrotic syndrome. Repeated renal biopsy confirmed tip lesion variant of FSGS, demonstrating excellent response to corticosteroid therapy with prednisolone 1 mg/kg/day; proteinuria declined from 7g/24h to 0.98g/24h and serum albumin increased from 0.9g/dL to 2.2g/dL within three months. This case underscores the importance of considering FSGS in RP-associated nephrotic syndrome and suggests potential shared immune/genetic mechanisms. To our knowledge, this represents both the first report of tip lesion FSGS in RP and the first documented familial RP case with FSGS development.