A Case of Minicore Myopathy

ABSTRACT

Minicore myopathy, an uncommon condition, is one of congenital myopathies. It is characterized by multifocal areas of degeneration in muscle fibers. The minicores consist of numerous small areas of decreased oxidative enzyme activity. The axis of the lesion is perpendicular or parallel to the long axis of the muscle fiber. The phenotype has been described as predominantly proximal, static or only slowly progressive muscle weakness. We report a 4 year-old-girl with respiratory failure, thoracic scoliosis, hypotonia and facial weakness, who was diagnosed as minicore myopathy by muscle biopsy. The laboratory investigations, such as creatine phosphokinase and lactic dehydrogenase levels, and the nerve conduction velocity were normal. The muscle biopsy showed marked size variations of myofibers, marked endomyseal and perimyseal fibrosis, and moderate fatty changes in myofibers. The histochemical studies showed multiple focal losses of mitochondria. These findings are consistent with minicore type congenital myopathy.