Localised nodular myositis: a clinical and pathological variant of polymyositis.

Three cases of a painful, inflammatory, nodular myopathy in young and middle-aged adult males are described. In two of the cases the nodular process gradually evolved into a diffuse proximal myopathy accompanied by dysphagia, and manifesting the so-called "facioscapulohumeral syndrome". The electromyogram (EMG) in all three cases was "myopathic" in type and in two cases abnormalities consistent with an inflammatory muscle disorder were seen. Muscle biopsy revealed a consistent pattern of intense, predominantly interstitial, pleomorphic infiltration of muscle with scattered foci of muscle fibre destruction and regeneration, which resembled muscle infarcts. It is suggested that this syndrome, whilst readily recognizable from both the clinical and pathological standpoints, is not a nosological entity in its own right but rather an unusual presentation of polymyositis.