Diagnostic value of abdominal fat tissue aspirate in familial amyloid polyneuropathy.

To confirm amyloid deposition we performed aspiration biopsy of abdominal fat tissue in 14 patients with type I familial amyloid polyneuropathy (FAP). All patients, about half of whom were at an early stage of disease and lacking severe neurological disabilities, showed positive amyloid deposition in preparations stained with Congo red. On light and electron microscopic examinations deposits of amyloid were observed around fat cells and small vascular walls, and among collagen bundles. All patients in the study were demonstrated to have a variant transthyretin in their sera by radioimmunoassay. Abdominal fat tissue aspiration can be easily performed with an ordinary syringe and is very sensitive for detecting amyloid deposition. The procedure is valuable in the diagnosis of type I FAP patients with actual deposition of amyloid substance, even at an early stage.