Renal cell carcinoma presenting as AA amyloidosis: a case report and review of the literature

A 47-year-old Caucasian man developed mild diarrhoea associated with more than 10 kg weight loss, severe fatigue and anaemia. Endoscopy demonstrated deposits of AA amyloid within the gastrointestinal tract. He had heavy proteinuria with a serum albumin of 15 g/L consistent with systemic AA amyloidosis. He had no symptoms to suggest an underlying chronic inflammatory condition but had CRP 130 mg/L and SAA 474 mg/L. In an attempt to identify the source of his inflammatory response, he underwent a contrast-enhanced whole-body computed tomography scan, which revealed a necrotising mass lesion in the right kidney consistent with a renal cell carcinoma. It also showed non-mechanical obstruction of the small bowel and, immediately post-imaging, the patient developed intractable vomiting followed by oliguric renal failure requiring haemodialysis. Despite his renal and gut failure, he underwent right radical nephrectomy without further complications. Histology showed complete resection of a clear cell renal cell carcinoma and renal amyloid deposits. Post-surgery, his acute-phase response decreased to normal, consistent with the renal cell carcinoma acting as the inflammatory stimulus. Although he remains dialysis dependent, his gut function improved and he has regained both normal weight and serum albumin. Our case demonstrates partial resolution of AA amyloidosis with removal of the inflammatory source.