Diagnostic screening of systemic amyloidosis by abdominal fat aspiration: an analysis of 100 cases

Congo red staining of abdominal fat aspirates was used as a screening procedure for systemic amyloidosis in 100 consecutive patients with symptoms suggestive of systemic amyloidosis. Nine samples were positive for amyloid. To assess the reliability of the method, we reviewed the patients' clinical records and their other biopsy data. All nine patients with positive fat specimens had a clinical course suggestive of amyloidosis. Fat aspirates were positive in nine of 11 patients with documented systemic amyloidosis. The sensitivity of the abdominal fat aspiration-amyloid technique was 82%, its specificity was 100%, and the predictive value of a positive result was 100%. Sixteen patients underwent both cutaneous biopsy and abdominal fat aspiration, and the results of Congo red staining were concordant in all cases. Although this method requires training to avoid sampling difficulties, abdominal fat aspiration is a highly reliable screening procedure for the diagnosis of AL amyloidosis, AA amyloidosis, and familial amyloidotic neuropathy (FAP).