[Morphology of metabolic myopathies].

While muscular lesions in endocrine or metabolic diseases are fairly common primary metabolic myopathies are rare. In these, the metabolic fault is in the muscle fibre itself, which takes on a vacuolated appearance. In the majority of these myopathies there is an abnormality of the glycogen or fat metabolism due to the absence of a specific enzyme in most cases. By contrast, the pathogenesis of the so called mitochondrial myopathies is not yet well understood.