Adult-onset nemaline myopathy and monoclonal gammopathy: a case report

A 47-year-old female developed proximal limb weakness after hysterectomy fo r uterine fibromatosis. Muscle strength slowly improved, but relapse occurr ed at age 52. She presented with progressive gait difficulty: proximal limb weakness, and painful calves. Family history was not contributory Cranial nerves, deep tendon reflexes, and sensation were normal. Serum creatine kin ase was normal. An IgG kappa monoclonal protein was found Nerve conduction studies were normal, bur EMG showed brief small polyphasic motor unit actio n potentials with early recruitment in proximal muscles. Muscle biopsy show ed abundant rods, atroptric muscle fibres, and type 1 fibre predominance. T he sarcolemma was immunoreactive for IgG kappa. Plasmapheresis was unsucces sful, but methylprednisolone and azathioprine led To moderate improvement o f muscle strength, associated with reduced monoclonal protein levels. This is rite third case report, describing the association of monoclonal gammopa thy and late-onset nemaline myopathy presence of a monoclonal protein at th e sarcolemma and responsiveness to immunosuppressive treatment ore suggesti ve of a dysimmune origin.