[Autophagic vacuolar myopathies: what we have learned from the differential diagnosis of vacuoles in muscle biopsy].

Establishing the correct etiological diagnosis of autophagic vacuolar myopathies (AVM) is an imperative since the recent availability of the enzyme replacement therapy for the treatment of Pompe disease. Recent recognition of the complex functional pathology of these disorders dramatically changed the view on their pathogenesis and it may lead to identification of new approaches in the therapy. Muscle biopsy is a useful tool for the differential diagnosis of the AVM; however, in some cases it may fail. Through a series of five short case studies we aim at demonstrating the histopathological findings and differential diagnosis of some AVM (Pompe disease, Danon disease and chloroquine myopathy) in muscle biopsy. We also want to address the fact that the way to the correct diagnosis of these disorders can be quite complicated. Awareness of these diseases and the availability of a dry blood spot test for the non-invasive diagnosis of Pompe disease represent a good basis for detecting patients who are still kept under other diagnoses and thus escaping treatment.