“A GUT FEELING”: DETERMINING THE CAUSE OF A CASE OF AA AMYLOIDOSIS
Dr Felicity Sartain1, Dr SHAUN CHANDLER2, Dr DHARMENAAN PALAMUTHUSINGAM2, Dr SAW YU MON2
1Cairns Hospital, Cairns, Australia, 2Royal Brisbane and Women’s Hospital , Herston, Australia, 3Princess Alexandra Hospital, Woolloongabba, Australia
Background: AA Amyloidosis is caused by states of chronic inflammation. These can be chronic inflammatory conditions, infections or malignancy. Rarely unilateral Castleman disease can be a cause of AA Amyloidosis.
Case Report: A 46-year-old female was referred to renal clinic with hypoalbuminaemia (24g/L), proteinuria (3.1g/24hrs) and preserved kidney function (Creatinine 70umol/L, eGFR >90ml/min/1.73m2). Her background only included obesity.
Ultrasound and serological testing, including serum protein electrophoresis and free light chains, were unremarkable. The kidney biopsy demonstrated segmental expansion of glomeruli with homogenous eosinophil acellular material, positive for congo red stain and green-yellow birefringence under polarised light. Immunohistochemistry was positive for amyloid A protein.
A bone marrow aspirate and trephine demonstrated amyloid deposits in the vessels outside of the marrow, with clonal population. Her serum amyloid A level was 39mg/L.
Extensive screening for a secondary cause of AA Amyloidosis was negative, and it was thought to be secondary to obesity. She was trialled on oral colchicine with no effect.
Two months later, the patient noted a palpable lump in her upper abdomen. A positron emission tomography scan was performed due to concerns for a malignant process, and this demonstrated an intensely FDG avid abdominal mesenteric lymph node. Excisional biopsy demonstrated histology consistent with unicentric Castleman disease, plasma cell variant. She underwent a complete resection later that year. Her CRP, the amount of proteinuria and serum Amyloid A levels have improved since surgical resection.
Conclusion: In patients with AA Amyloidosis due to unicentric Castleman disease systemic symptoms may resolve with resection of the lymph node. This case highlights the importance of identifying the cause of AA Amyloidosis to direct management.