Peripheral and autonomic nerve lesions in systemic amyloidosis. Three pathological types of amyloid polyneuropathy

Twenty autopsy cases of systemic amyloidosis, consisting of 10 cases of primary systemic amyloidosis, 6 cases of myeloma-associated amyloidosis, 2 cases of secondary amyloidosis, and 2 cases of hereditary amyloidosis, were studied clinically and pathologically with special reference to peripheral and autonomic neuropathy. The peripheral nerves of 8 cases with clinical manifestations of polyneuropathy showed deposition of amyloid in the endoneurium, capillaries within the nerve fascicles, perineurium, and epineurium with a loss and degeneration of the nerve fibers. In the peripheral nerve lesions of these cases, there appeared to be three types: I. Endoneurial deposition of amyloid--loss of unmyelinated and small myelinated fibers, II. vessel wall deposition of amyloid in the vasa nervorum--loss of large myelinated fibers; and III. a mixed type of I and II. While the peripheral nerves of 12 cases without neuropathy mainly showed deposition of amyloid in the epineurium and perineurium with well preserved nerve fibers. The possibility was considered that the pathogenesis and variety of peripheral and autonomic nerve lesions might be related to the various molecular features of amyloid proteins or their precursors in systemic amyloidosis.