Use of abdominal fat tissue aspirate in the diagnosis of systemic amyloidosis.

The needle aspirate of abdominal fat was investigated for its sensitivity in giving a tissue diagnosis in 32 consecutive patients with systemic amyloidosis. The fat tissue aspirate was stained with Congo red and examined with a polarizing microscope. Positive results were obtained in 95% (18/19) of patients with primary (AL) amyloidosis, 66% (4/6) of patients with secondary (AA) amyloidosis, and 86% (6/7) of patients with the heredofamilial (AF) form. The overall positive yield was 88% (28/32). Abdominal fat tissue aspiration is proposed as a simple, rapid, and effective technique for the diagnosis of amyloidosis. The prevalence of positive results in known amyloid disease are comparable with the rectal biopsy specimen and are more frequent than gingival or skin biopsy specimens.