Resumo

TAVARES, Isabel et al. Renal amyloidosis: classification of 102 consecutive cases. Port J Nephrol Hypert [online]. 2014, vol.28, n.3, pp.201-209. ISSN 0872-0169.

Amyloidoses are a group of heterogeneous diseases classified according to the nature of their causative amyloid proteins. Commonly, paraffin-embedded tissue is used for the typing of amyloid by immunohistochemistry. DNA analysis should always be considered if hereditary amyloidosis is suspected. Since the kidneys are one of the organs that are most commonly involved in amyloid deposition in systemic amyloidoses, we screened 102 consecutive cases with biopsy-proven amyloid disease by immunohistochemistry. DNA analysis was performed to confirm a diagnosis of hereditary amyloidosis. Demographic characteristics, underlying disease and clinical data at the time of renal biopsy were obtained by retrospective review of medical records. The amyloidosis type according to immunohistochemical amyloid protein identification was AA in 60 (58.8%) patients, AL in 21 (20.6%), AFib in four (3.9%), ATTR in two (2.0%), AApoAI in one (1.0%), ALys in one (1.0%) and combined AL and AA in one (1.0%). The type of protein could not be classified in 12 (11.7%) patients: eight (7.8%) because of negative immunohistochemistry and four (3.9%) due to the lack of adequate tissue. DNA analysis confirmed AFib and ATTR cases by the identification of the point mutations FGA p.Glu545Val and TTR p.Met51Val, respectively. Mean age at diagnosis was 53.3 years (49.4 for AA, 63.0 for AL and 53.9 for AFib). Chronic infections were the most frequent disorder associated with AA amyloidosis, mainly tuberculosis, and only one patient had familial AA associated with Muckle-Wells syndrome. Nephrotic syndrome was the most frequent clinical manifestation, independently of the amyloid type. In our series, AA amyloidosis is still the most frequent type of systemic amyloidoses. Six patients had unequivocal hereditary amyloidosis. Immunohistochemistry did not establish the precursor protein in almost 8% of patients; however, an improvement could be obtained using a wider panel of amyloid antibodies.

Palavras-chave : Amyloidosis; diagnosis; hereditary; immunohistochemistry; kidney.

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