Ultrastructural Aspects of Apoptosis in Systemic Sclerosis Inflammatory Myopathy

Muscle biopsies from two female patients with systemic sclerosis (SS) and an inflammatory myopathy were studied ultrastructurally in relation to the possible presence of apoptosis in skeletal muscle fibers. Undergoing apoptosis showed characteristic morphological features of this process, including chromatin aggregation as well as nuclear and sarcoplasmic partition into membrane bound-vacuoles (apoptotic bodies) which contained autophagosomes, mitochondria, isolated myofilaments and nuclear material. Vacuoles exhibited different diameters and were covered by single membranes, appearing beneath basement membrane. Apoptosis occurred in some fiber segments as in necrosis or included whole atrophied fibers. These results indicate that apoptosis coexists with necrosis in the inflammatory myopathy of SS.