Utility of subcutaneous fat aspiration for diagnosing amyloidosis in patients with isolated peripheral neuropathy

Objective: To determine the value of subcutaneous fat aspiration in patients with sensorimotor peripheral neuropathy. Patients and Methods: We retrospectively reviewed the medical records of all patients undergoing subcutaneous fat aspiration for suspected amyloidosis from January 1, 1994, through December 31, 1999. We classified patients undergoing subcutaneous fat aspiration due to peripheral neuropathy into 2 groups: (A) those with isolated peripheral neuropathy and (B) those with any family history and laboratory or clinical findings typically associated with systemic amyloidosis. Results: The study population consisted of 450 patients with peripheral neuropathy in whom fat aspiration was performed for suspected amyloidosis. This constituted 56% of all fat aspirations performed during the study period. Group A had 143 patients, and group B had 307 patients. None of the patients in group A had a positive subcutaneous fat aspirate, whereas 17 patients (6%) in group B had a positive subcutaneous fat aspirate (P=.002, Fisher exact test). The subcutaneous fat aspirate was most commonly positive in patients with a monoclonal protein or other clinical findings associated with amyloidosis. Conclusions: The yield of a subcutaneous fat aspirate in patients with isolated peripheral neuropathy and no other associated family history, signs, or symptoms of amyloidosis is low. Subcutaneous fat aspiration should be reserved for evaluating patients with peripheral neuropathy who also have findings associated with systemic amyloidosis.