[Secondary (AA) renal/bone amyloidosis complicating rheumatoid arthritis]

Amyloidosis is a clinical entity that results from deposition of an extracellular protein material that causes disruption in normal architecture and impairs function of multiple organs and tissues. Secondary amyloidosis (AA) is a rare but serious complication that appears in the context of cancer, chronic inflammation, and chronic infectious disease, including rheumatoid arthritis. Renal failure is the most common clinical presentation of AA, ranging from nephrotic syndrome and impaired renal function to renal failure, with a potential for high morbidity. We present a case of a 52-year-old female patient diagnosed with rheumatoid arthritis at age 27. She was hospitalized due to worsening clinical condition. Physical examination revealed marked peripheral edema in both lower extremities. Laboratory tests showed an increase of inflammatory reactants, anemia, electrolyte disbalance, and severe hypoalbuminemia and hypoproteinemia. She had proteinuria 15.4 g/24 h and renal function estimated by creatinine clearance was 78 mL/min, within the second degree of chronic kidney disease. Renal biopsy was performed for evaluation of renal insufficiency with nephrotic range proteinuria. Congo red staining showed the presence of characteristic amyloid deposits that immunoreacted with the antibody against amyloid A protein, thus confirming the diagnosis of secondary amyloidosis.