Impact of hematologic complete response in the treatment of sporadic late‐onset nemaline myopathy associated with monoclonal gammopathy

Abstract

Monoclonal gammopathy of undetermined significance (MGUS) may be associated with pathologies with severe neuromuscular manifestations, namely POEMS syndrome and AL amyloidosis. [1][2][3][4] Another less-known association is with a rare disorder named sporadic late-onset nemaline myopathy (SLONM). [5][6][7][8][9][10] More than half of these patients have a simultaneous MGUS diagnosis. 11,12 Diagnosis is confirmed by muscle biopsy with detection of intracytoplasmic nemaline rod bodies, representing Z-disc disorganization products that immunoreact with alfa-actinin and myotilin, accompanied by progressive atrophy of the muscle fiber. 5,11 Necrotic or regenerating fibers and inflammatory infiltration are usually absent. 13 Clinically, SLONM appears mostly after the fourth decade of life as a rapidly progressing tetraparesis,