I have a very challenging case to share and am looking for some guidance.
A 32 M, previously well whose only past history is significant for regular cocaine use.
He presents with a 4 month history of peripheral edema but no other specific symptoms or signs. Initial creatinine was 140 umol/L with 20 grams of urinary protein per day. He underwent renal biopsy (shown below) which was read as:
MEMBRANOPROLIFERATIVE GLOMERULONEPHRITIS WITH FOCAL ACTIVE CRESCENTS AND LINEAR GLOMERULAR CAPILLARY LOOP STAINING FOR IgG
a) 1 of 23 glomeruli globally sclerosed.
b) 5 glomeruli with active crescents.
c) No significant interstitial fibrosis and tubular atrophy.
d) Minimal arterial sclerosis and no arteriolar hyalinosis.
The biopsy shows MPGN type nephritis with focal cellular crescents. Immunofluorescence shows linear IgG staining along glomerular capillary loops. This type of glomerular injury has been reported in the literature as ATYPICAL ANTI-GBM NEPHRITIS (Nasr et al. The clinicopathologic characteristics and outcome of atypical anti-glomerular basement membrane nephritis. Kidney International (2016) 89, 897-908).
His work up was otherwise fairly unremarkable. Other than anemia, he had no serum anti-GBM by IF nor ELISA; atypical anti-GBM was not detected in blood; ANA was negative; C3 was transiently low but then normalized; viral serologies were negative.
Over the last month, he was treated by me as crescentic anti-GBM using PLEX, IV solumedrol and oral cyclophosphamide. He proteinuria fell from 20 g to 10 g per day but creatinine rose from 140 t o 180 umol and continued use of cyclophosphamide is now limited by HGB of 80.
Can anyone suggest an alternative treatment here? We have considered rituximab and eculizumab as salvage therapy.
Thank-you for your help,
Dr. Jordan Weinstein