DIAGNOSING AL AMYLOIDOSIS:
Kidney or Liver Biopsy: ~90% sensitive
Abdominal Fat Pad Aspirate: ~60-80% sensitive
Rectal Biopsy: ~50-70% sensitive
Bone Marrow Biopsy: ~50-55% sensitive
Skin Biopsy: ~50% sensitive
For ease, convenience and yield, if AL amyloidosis is still suspected in the setting of a negative fat bad and bone marrow biopsy, then the affected organ should be biopsied (gold standard).