[The clinical pathological characteristics and follow-up of 4 cases of immune-mediated necrotizing myopathy].

Objective: To characterize the clinical, electrophysiology and neuropathological features of 4 cases with immune-mediated necrotizing myopathy (IMNM).

Methods: We retrospectively analyzed the clinical, electrophysiology, neuropathological characteristics of 4 IMNM patients with muscular and skin biopsy in our department during 4 years (from January 2011 to January 2014).

Results: Among these 4 patients, 2 were men and 2 were women (aged 37 to 58 years) with disease duration ranging from 1 month to 60 months. Two patients were with acute onset and 2 with chronic onset. All 4 patients had proximal muscle weakness with three patients with cervical flexor muscle weakness and one with respiratory muscles weakness and noninvasive ventilator assisted respiration. One patient had interstitial lung disease. The anti-signal recognition particle antibodies were strong positive in all 4 patients. Muscle biopsy showed group necrotizing and regenerating fibers in one patient and few scattered necrotizing and regenerating fibers in the other 3 patients. Both muscle fiber hypertrophy and muscle fiber atrophy together with proliferation of connective tissue on endomysium could be viewed in all 4 patients. However, very few inflammatory cells were detectable in patients. One patient was treated with corticosteroids and the other three were treated with combination of corticosteroids and immunosuppressant drugs.

Conclusions: IMNM is characterized by heterogeneity at disease onset, severity and iInvolvement of muscles with, however, similary pathological changes including the presence of numerous necrotic and regenerating fibers with little or none inflammation. Corticosteroid and/or immunosuppressant is effective for patients.