[Value of aspiration biopsy of subcutaneous fat in amyloidosis]

Fine-needle aspiration of subcutaneous fat (FNAF) was performed in 24 patients, 12 with previously diagnosed amyloidosis presenting with proteinuria or nephrotic syndrome, and 12 presenting a nephrotic syndrome without amyloidosis on renal biopsy. FNAF was positive in 10 of 12 patients with amyloidosis (sensitivity: 83%) and negative in 12 of 12 patients with non-amyloid nephrotic syndrome (specificity: 100%). Considering a 2.5 to 10% prevalence of amyloidosis in adult patients with proteinuria or nephrotic syndrome, a positive FNAF is diagnostic of amyloidosis, and a negative FNAF rules out the diagnosis with a probability of 98 to 99%. FNAF is a simple and safe method which can be useful in patients who cannot undergo a renal biopsy.