The performance of telescoping fat pad biopsies for detecting systemic amyloidosis: a four and a half year retrospective analysis and brief review of the fine needle aspiration literature.

Systemic amyloidosis has historically been diagnosed by organ biopsy and Congo red staining, with reported sensitivities that exceed 90%. The abdominal fat pad fine needle aspiration (FNA), introduced in the 1970's, carries sensitivity estimates largely derived from studies with deficiencies. Patient follow-up is often unclear and proportionally low numbers of patients are verified as true negatives. Issues in other studies include only testing verified systemic amyloidosis cases. The telescoping fat pad biopsy (TFPB) is used as an alternative to FNA and is similarly carried out quickly with low morbidity. Although the two methods would seem to be comparable intuitively, this has not been established because sensitivity data for the TFPB method is scarce to non-existent. The charts of 58 consecutive patients who underwent TFPB screening for amyloidosis in a single hospital from August of 2010 to January 2015 were examined. All six TFPB positive patients were determined to be true positives. Eight TFPB negative patients were concurrently determined to have systemic amyloidosis by other methods - organ biopsy (7) and mass spectrometry (1) resulting in a 43% sensitivity. The remaining patients were categorized into 25 true negatives and 18 that were indeterminate based on clinical course and other biopsy results.