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Kidney Week

Abstract: TH-PO575

Mycobacterium simiae: A Rare Cause of Renal AA Amyloidosis

Session Information

Category: Glomerular Diseases

  • 1401 Glomerular Diseases: From Inflammation to Fibrosis

Authors

  • Abbasi, Momen, Hadassah University Medical Center, Jerusalem, Jerusalem, Israel
  • Potruch, Assaf, Hadassah University Medical Center, Jerusalem, Jerusalem, Israel
  • Eyal, Ophir, Hadassah University Medical Center, Jerusalem, Jerusalem, Israel
Introduction

Mycobacterium Simiae is a prevalent nontuberculous mycobacterium (NTM) that can become pathogenic to immunocompetent individuals with underlying lung disease. Rarely, untreated chronic NTM infections can result in AA amyloidosis.

Case Description

74-year-old male with COPD presented with weight loss, nocturnal fever, elevated ESR and anemia. Cultures, serology tests, and GeneXpert for tuberculosis were negative. Normal FLC ratio. Borderline paraprotein detected only in serum. PET-CT showed increased uptake in upper right lung, small mediastinal and hilar lymph nodes. He was treated pneumonia. M. simiae grew in two sputum cultures after 4 weeks, repeated cultures were advised but not done. 5 months later patient presented with severe nephrotic syndrome, albumin <20 g/L and protein/creatinine ratio 20.8 g/g. Borderline paraprotein reported only in urine. Normal FLC ratio. Kidney biopsy was consistent with renal AA amyloidosis by immunostaining and lack of light chain restriction. PET CT revealed consolidations in right lower lobe and cavitations in both lower lobes. BM biopsy exposed dysplastic changes. Diagnosis of systemic AA Amyloidosis due to untreated M. simiae infection was made. He was treated with azithromycin, ciprofloxacin, cotrimoxazole but succumbed to his disease.

Discussion

NTM rarely cause amyloidosis with 5-8 years interval between NTM diagnosis and amyloidosis development after which mean survival time is 10 months. We believe that M. simiae caused amyloidosis in this case because of longstanding inflammation and negative extensive workup for other causes. We found only one case of AA amyloidosis associated with M. simiae lung infection with renal involvement but no nephrotic syndrome described.
We present a rare case of nephrotic syndrome due to AA amyloidosis associated with M. simiae infection. Despite prolonged inflammation, M. simiae was diagnosed 5 months prior to AA amyloidosis diagnosis. Treatment was started late in the course of the disease and despite that he died within few weeks. This highlights the importance of early diagnosis and treatment of active M. simiae infection.

Congophilic amyloid deposits under polarized light showing apple-green birefringence