P0423CLINICOPATHOLOGICAL STUDY OF RENAL AMYLOIDOSIS
Authors: Kaul Anupma 
Published: June 2020

Background and Aims

Amyloidosis constitute a heterogenous group of disorders characterized by extracellular deposition of abnormally folded proteins in different tissues and organs leading to organ dysfunction. An emphasis has been made to classify, grade and score the amyloid deposits in different renal compartments and correlate them with the clinical features, type of amyloid and outcome.

Method

The study included all renal biopsies done in department of nephrology diagnosed as amyloidosis in association with Department of Pathology, SGPGIMS from January 2009 to December 2018 and retrospectively analysed. Besides biochemical parameters ,serum and urine electrophoresis ,immunofixation ,bone biopsy ,FNAC and kidney biopsy was done for the diagnosis.

Results

One hundred forty seven (147) renal biopsies diagnosed as Amyloidosis at the Department of Pathology, SGPGIMS, Lucknow from January 2009 and December 2018 .The mean age was 51.33 ± 14.50 years (Median: 52 year), most common age group affected with Renal Amyloidosis was 50-60 years(6 th decade) in males, while it was one decade younger in females (40-50years). Multiple myeloma as the primary disease was present in 18/147 (12.2%). History of chronic inflammatory disease was found in 65 patients (44%). Tuberculosis was the most common infection while rheumatoid arthritis (18.5%) was found to be the second most commonly associated chronic inflammatory condition. Mean serum creatinine was 2.04 ±1.72 mg/dl. Peripheral neuropathy and bleeding episodes were rarely seen (&lt;5%). Nephrotic range proteinuria was found in 78% Only eight out of eighteen patients with Multiple myeloma showed reversal of A:G ratio. M-band was present in 34 patients . Lambda light chain was found more commonly associated with renal amyloidosis. Out of 71, 27 aspiration cytology smears revealed congophilic deposits which showed apple green birefringence on polarizing microscopy. Bone marrow biopsy was performed in 76, among them 17 patients showed &gt; 10% plasma cells. Histology commonly seen was diffuse mesangio capillary in 77%, followed by advanced amyloidosis (20%). Most of the renal biopsies (84%) showed amyloid deposition in &gt;50% area of glomeruli. Most of the renal biopsies (41.5%) showed mild tubular atrophy. Renal amyloid prognostic score (RAPS) was calculated combining all scores in different renal compartments revealed 74% patients belonged to Grade III. Immuno histochemistry for typing of renal amyloid revealed SAA in 61, two cases were placed in a different group, termed as dual AL+AA positive. one case with positive ALect2 deposits in renal biopsy. Survival analysis showed showed that AL had poor overall survival as compared to AA typePatients with high serum creatinine value (&gt;2.0 mg/dl) had poor survival as compared to the patients with serum creatinine &lt;2.0mg/dl. significant poor survival in patients withcardiomyopathy (p value=0.004) and hypotension (p value=0.026). High burden of plasma cells (&gt; 10%) in bone marrow aspirate also showed significant poor survival.

Conclusion

Final typing of amyloid deposits in kidney biopsy with clinicopathological evaluation revealed AA was the predominant subtype comprising of 50% (n=73) of renal amyloidosis. AL was 33% (n=48) of all cases. The different class of pattern of amyloid deposition correlated well with the grade of amyloid deposition in renal biopsy. Poor survival outcomes are evident with patients with hypotension ,cardiomyopathy, higher grades of amyloid on histology, serum creatinine &gt; 2 mg% and high burden of plasma cells (&gt;10%) in bone marrow aspirate. Thus the number of patients with cardiomyopathy, hypotension and &gt; 10% plasma cells in bone marrow aspirate performed poorly however the study is smalland needs to be validated on a larger cohort.