Quiz Form

Question Date: 23/08/2023

Question: A 65 year old male presents with painful neuropathy since a year. He has significant weight loss. On examination, he has distal weakness with sensory loss in arms and legs. There is postural hypotension and leg edema with cachexia. He is non diabetic and work up for malignancy and HIV is negative. Which of these statements is true regarding diagnosis of primary amyloid neuropathy?

Options:

• Monoclonal IgM antibodies are seen in majority
• Long term prognosis is favorable
• Combined nerve and muscle biopsy is the most sensitive diagnostic test
• IVIg is effective first line treatment

Correct Answer: Combined nerve and muscle biopsy is the most sensitive diagnostic test

Explaination: Primary AL amyloidosis is the most common form of amyloid neuropathy. It is due to clonal plasma cell proliferation producing monoclonal protein or light chains. Serum light chain assay is the most sensitive test to detect monoclonal protein. Amyloid can be detected in abdominal fat, bone marrow and rectal biopsy. In the presence of neuropathy, combined nerve and muscle biopsy has a diagnostic yield of 90%. It presents with weight loss and cardiac, renal and hepatic dysfunction. Neuropathy is present in a third and typically is a painful neuropathy with autonomic dysfunction and median entrapment at wrist. Periorbital purpura (raccoon eyes) and macroglossia may be seen in 20%. The prognosis is poor with median survival of 18 months or less. High dose melphalan, stem cell transplantation and bortezomib have been used for treatment

Reference: Katirji B. Disorders of Peripheral Nerves. Bradley and Daroffs Neurology in Clinical Practice. 2022. Ch 1061853.