Myositis mimics

Proximal muscle weakness in children, as well as adults, can be the presenting feature of a wide range of diseases including but not limited to the idiopathic inflammatory myopathies, muscle dystrophies, metabolic, endocrine, and drug-induced myopathies. Certain diagnostic clues such as selective muscle involvement in inherited dystrophies, cramping on exertion in metabolic myopathies, diffuse muscular pain in endocrinal myopathies, and relevant drug history along with a lack of appropriate treatment response to steroids should be considered. Awareness of other possibilities and a keen eye to identify the mimics may avoid diagnostic delays and allow timely treatment. In this review, we cover some of the salient features of the various myositis mimics and the pertinent investigation findings as well as gray areas which may confound recognition of the underlying etiology. Later, we discuss key features of certain mimics while providing an overview of the differential diagnosis and clinical management for treating clinicians.