GLOMERULAR DISEASE DIAGNOSIS
A Potpourri of Cases from the Collection of Dr. Bijol
In this session of Nephropathology Essentials, Dr. Bijol utilized a case-based approach to review a variety of important nephropathology topics. Our Moderator’s Notes are derived from her live presentation.
By Dr. Pravir Baxi
Key points:
- Rarely, patients can have chronic, indolent glomerulonephritis that may be undiagnosed due to the absence of overt nephrotic/nephritic findings (e.g., asymptomatic, non-nephrotic proteinuria). These patients can potentially progress to have clinically significant renal disease.
- Histologically active lesions on a renal biopsy can be missed or appear absent due to the focal nature of the disease and/or a result of a sampling error (e.g., medulla versus cortex). This can lead to delay in diagnosis or inadequate treatment, leading to an increased risk of CKD/ESKD.
- Drug-induced vasculitis
- In patients with pauci-immune (+ANCA) crescentic glomerulonephritis (GN), a complete search for secondary causes, including medications and infections, is recommended.
- Common medications: hydralazine, allopurinol, anti-thyroid drugs (propylthiouracil>>methimazole), minocycline, penicillamine, levamisole
- Typically, these patients will have very high MPO or PR3 levels, elevated ANA, low C3/C4, or atypical features on histopathology, such as low-level Ig deposition.
- Vascular endothelial grow factor (VEGF) inhibition
- VEGF inhibitors act through various mechanisms (via numerous downstream signaling pathways) and can lead to nephrotoxicity.
- Most common renal presentations related to these agents are hypertension, proteinuria (which can progress to full nephrotic syndrome), and thrombotic microangiopathy (TMA). ATN has also been described.
- On renal biopsy, common histologic findings include endotheliosis, podocytopathy, TMA, and MPGN-pattern of injury.
Selected References:
- Estrada CC, Maldonado A, Mallipattu S. Therapeutic Inhibition of VEGF Signaling and Associated Nephrotoxicities. J Am Soc Nephrol. 2019.
https://www.ncbi.nlm.nih.gov/pubmed/?term=30642877 - Hacking S, Uppal NN, Khan N, Ionescu M, and Bijol V. Systemic p-ANCA vasculitis with fatal outcome, arising in the setting of methimazole use. Clin Nephrol Case Stud. 2019.
https://www.ncbi.nlm.nih.gov/pubmed/31008018 - Radhakrishnan J, Perazella MA. Drug-induced glomerular disease: attention required! Clin J Am Soc Nephrol. 2015.
https://www.ncbi.nlm.nih.gov/pubmed/25876771
