Abstract: PUB383
Idiopathic Renal AA Amyloidosis with Bilateral Nephromegaly and Rapid Progression to ESRD: A Case Report and Literature Review
Session Information
Category: CKD (Non-Dialysis)
- 2302 CKD (Non-Dialysis): Clinical, Outcomes, and Trials
Authors
- Harrisson, Raphael Ronald, Universite de Sherbrooke, Sherbrooke, Quebec, Canada
- Chen, Anjellica, McGill University, Montreal, Quebec, Canada
Introduction
AA amyloidosis, a complication of chronic inflammation, is characterized by the extracellular deposition of the serum amyloid A (SAA) protein. This condition is often associated with infections, autoimmune diseases, and hereditary inflammatory disorders. However, cases without an identifiable trigger, referred to as idiopathic AA amyloidosis, are rare. Renal involvement is frequent, but bilateral nephromegaly and rapid progression to end-stage renal disease (ESRD) are unusual features. We present a case of idiopathic AA amyloidosis with these rare characteristics, highlighting the diagnostic challenges and discussing potential underlying mechanisms.
Case Description
A 30-year-old Afghan woman with a remote history of childhood pulmonary tuberculosis presented two months postpartum with nausea, vomiting, and lower extremity edema. She was found to have nephrotic-range proteinuria, creatinine of 1169 µmol/L (previously 60 µmol/L four months prior), and bilateral nephromegaly. Renal biopsy confirmed AA amyloidosis via Congo red staining, immunohistochemistry, and mass spectrometry. Extensive workup for inflammatory, infectious, autoimmune, and malignant causes was negative, including tests for active tuberculosis and malignancy screening via PET-CT. Genetic testing of over 400 relevant genes was unremarkable. A diagnosis of idiopathic AA amyloidosis was made. She required immediate hemodialysis and subsequently transitioned to peritoneal dialysis.
Discussion
This case highlights an aggressive form of idiopathic AA amyloidosis characterized by bilateral nephromegaly and rapid progression to end-stage renal disease, features more commonly associated with early-stage inflammatory diseases. Factors such as latent tuberculosis and obesity may have contributed through low-grade chronic inflammation, as suggested in some animal and human studies. SAA1 promoter screening could offer therapeutic insights, as a recently identified mutation may predict a favourable response to early IL-6 blockade therapy. Since no definitive treatment exists, management remains supportive, underscoring the need for further research to understand the condition and develop targeted therapies.