Anti-myelin-associated glycoprotein (anti-MAG) neuropathy is a chronic demy elinating neuropathy with predominant involvement of large sensory fibers and de posits of IgM and complement on sural nerve myelinated fiber...Anti-myelin-associated glycoprotein (anti-MAG) neuropathy is a chronic demy elinating neuropathy with predominant involvement of large sensory fibers and de posits of IgM and complement on sural nerve myelinated fibers. We assessed the p resence of IgM deposits on skin myelinated nerve fibers and the involvement of u nmyelinated axons in anti-MAG neuropathy. Skin biopsies were performed in 14 pa tients with anti-MAG neuropathy, in 8 patients with chronic inflammatory demyel inating polyradiculoneuropathy (CIDP), and in 2 patients with IgM paraproteinemi c neuropathy. Biopsies were taken at the proximal thigh in 20 patients, at the d istal leg in 21 patients, at the proximal arm in 13 patients, and at the hand or fingertip in 10 patients. We found IgM deposits on dermal myelinated fibers in all anti-MAG neuropathy patients, with a greater prevalence at the distal site of the extremities. Deposits were located throughout the length of the fibers an d at the paranodal loops. CIDP and IgM paraproteinemic neuropathies did not show any deposit of IgM. Anti-MAG neuropathy and CIPD patients showed a decrease in epidermal nerve fiber density reflecting an associated axonal loss. In anti-MA G neuropathy,both large-and small-diameter nerve fibers are affected, and spec ific deposits of IgM are found on skin myelinated nerve fibers.展开更多
文摘Anti-myelin-associated glycoprotein (anti-MAG) neuropathy is a chronic demy elinating neuropathy with predominant involvement of large sensory fibers and de posits of IgM and complement on sural nerve myelinated fibers. We assessed the p resence of IgM deposits on skin myelinated nerve fibers and the involvement of u nmyelinated axons in anti-MAG neuropathy. Skin biopsies were performed in 14 pa tients with anti-MAG neuropathy, in 8 patients with chronic inflammatory demyel inating polyradiculoneuropathy (CIDP), and in 2 patients with IgM paraproteinemi c neuropathy. Biopsies were taken at the proximal thigh in 20 patients, at the d istal leg in 21 patients, at the proximal arm in 13 patients, and at the hand or fingertip in 10 patients. We found IgM deposits on dermal myelinated fibers in all anti-MAG neuropathy patients, with a greater prevalence at the distal site of the extremities. Deposits were located throughout the length of the fibers an d at the paranodal loops. CIDP and IgM paraproteinemic neuropathies did not show any deposit of IgM. Anti-MAG neuropathy and CIPD patients showed a decrease in epidermal nerve fiber density reflecting an associated axonal loss. In anti-MA G neuropathy,both large-and small-diameter nerve fibers are affected, and spec ific deposits of IgM are found on skin myelinated nerve fibers.
