[Amyloidosis AA]

Amyloidosis remains one of the three major types of multisystemic amyloidosis, with immunoglobulinic (AL) and hereditary varieties. Recently, however, its incidence has been decreasing in Western countries. Inflammatory disorders are currently the major causes of amyloid-associated (AA) amyloidosis; first of all it is rheumatoid arthritis, then ankylosing spondylarthropathy and auto-inflammatory syndromes. Some tumours may lead to amyloidosis, including Castleman's disease. Complete surgery can result in regression of amyloid. It is not exactly known why some patients develop a progressive amyloidosis, whereas others do not. A permanent acute phase response, ideally evaluated with serial measurement of serum protein SAA, the precursor of the AA protein deposited in tissues, seems to be a prerequisite to the development of inflammatory (AA) amyloidosis. Genetic factors have however been recently emphasized. Nephropathy is the main clinical manifestation of amyloidosis. Serial search for proteinuria and serum creatinine measurement remain quite useful for detecting the first sign of renal impairment during chronic inflammatory disorders. A thorough diagnosis of AA amyloidosis deserves to gather whole clinical and pathological data, including immunohistochemistry. Some pitfalls exist and another type of amyloidosis should not be misdiagnosed as the AA variety. Ultimate renal failure and gut involvement with denutrition account for the persistent poor prognosis of AA amyloidosis. Current treatment aim at decreasing the inflammatory response; drugs targeting other steps of amyloid deposition are currently developed.