Diaphragm muscle pathology in Fukuyama type congenital muscular dystrophy

The diaphragm muscle pathology in four patients with Fukuyama type congenital progressive muscular dystrophy (FCMD) was reported. In the diaphragm muscle fibers of three patients aged more than 14 years exhibiting chronic respiratory failure, a lot of electron dense lesions, which varied in size but did not extend over the whole length of the muscle fibers, and a marked increase in mitochondria were observed as well as the dystrophic changes. The dense lesions, consisting of electron dense fibrillary material comparable to Z-band materials in electron density, seemed to be due to Z-band disruption leading to streaming and/or large aggregations of Z-band materials. No mitochondria or other microorganelles were found in these dense lesions. These findings are thought not to be specific to FCMD, but seem to reflect diaphragm muscle fatigue, because, there were no such lesions in the diaphragm muscle of a 2-year-old infant not exhibiting chronic respiratory failure or in muscle at other sites in all patients.