Case 1 History ---- A 79-year-old man with seronegative rheumatoid arthritis on methotrexate and adulimumab-ryvk experienced a few years of bilateral lower extremity sensory symptoms and asymmetric leg weakness on exam. Electrodiagnostic testing showed a sensorimotor axonal polyneuropathy. Neuromuscular ultrasound showed no abnormalities in nerves of the left leg. Neuropathy autoantibodies were negative. ANA was positive at 1:1280 in a speckled pattern. Biopsies of quadriceps and sural nerve were performed. The significant muscle pathologic findings are markedly atrophic muscle fibers with cytoplasmic accumulation of numerous autophagosomes and vacuoles. The membrane delimited vacuoles contained cytoplasmic debris including concentric membranes. The other pathology noted is the marked accumulation of mitochondria, most are subsarcolemmal or within the center of fibers.
