Laboratory Testing
The sine qua non for the diagnosis of amyloidosis is a tissue biopsy staining positive with Congo red and demonstrating green birefringence under polarized light microscopy. Electron microscopy will also show a classical fibrillar appearance in the extracellular matrix.
It is important to avoid over-staining the tissue with Congo red as this may give false results. The technique of subcutaneous fat pad aspiration offers a simple and relatively non-invasive approach to the diagnosis of systemic amyloidosis and is positive in 70-80 % of patients with systemic amyloidosis. If the fat is negative, but suspicion of disease is high, a biopsy of an involved organ system (e.g., heart, kidney, or liver) may need to be done to make the diagnosis. An involved organ is positive nearly 100% of the time.
Providers can send biopsy material for a second opinion, which should always be accompanied by an Amyloid Pathology Consultation Form, to:
Boston Medical Center
Department of Anatomic Pathology Accessioning Area
670 Albany Street, 3rd Floor Rm 328
Boston, MA 02118
Phone: 617-638-6994
Sending Tissue Samples for Amyloid Histopathology
Abdominal Fat Aspirate Procedure
Abdominal Fat Aspirate Staining Technique
Amyloid Pathology Consultation Form