The presence of esterase-positive lipofuscines and mitochondrial
dysfunction and accumulation inside muscle fibres were other
prominent histological findings. Lipofuscin formation is a manifestation
of reactive oxygen species (ROS)-induced damage, and their
relationship with the lysosomal compartment is also confirmed by
the presence of esterase-positive vacuoles in several autophagic vacuolarmyopathies,
such as Danon disease and X-linkedmyopathy with
excessive autophagy