Inflammatory myopathy associated with myasthenia gravis with and without thymic pathology: Report of four cases and literature review

Abstract

Introduction: The association of myasthenia gravis (MG) and inflammatory myopathy is rare and often only one of the diseases is diagnosed. Thymus pathology may be in the origin of such disease association.

Methods: We described four patients with both MG and inflammatory myopathy.

Results: These cases correspond to 2.3% of our MG cohort. Case 1: MG, polymyositis and thymolipoma; case 2: MG and necrotizing myopathy without thymic pathology on a background of scleroderma, Raynaud's phenomenon, esophageal dysmotility, sclerodactyly, telangiectasia (CREST); case 3: MG and dermatomyositis without thymic pathology; case 4: MG and dermatomyositis with type C thymoma.

Discussion: The recognition of these neuromuscular co-morbidities contributes to (i) understanding their pathogenic mechanisms, (ii) developing better management approaches and (iii) further improving disease outcomes.

Keywords: Muscle biopsy; Myasthenia gravis; Myositis; Thymoma.