Modificazioni ultrastrutturali dei miocardiociti in un caso di rabdomioma cardiaco in un cinghiale (Sus scrofa)

In humans, cardiac rhabdomyoma – characterized by glycogen-filed muscle cells with an occasional spiderwebappearance – represents the most common primary cardiac neoplasm in children, while it has beenrarely reported in veterinary medicine, except in pigs . The etiology and pathogenesis are still unknown andit is thought to be a hamartoma of myocardiocytes or, less likely, Purkinje fiber cells. The present casereport provides a wide ultrastructural description of a grossly and histologically diagnosed cardiacrhabdomyoma observed in a 2-years-old female wild boar. Trasmission electron microscopy revealed asevere cytoplasmic vacuolization associated with myofibrillar degeneration and occasional faint A and Hbands. Vacuoles contained amorphous granular material, glycogen, filaments and remnants of myofibrils.Moreover, the aberrant formation of sarcomeres, with accumulation of disorganized myofibrils, especiallythick filaments, and irregular deposits of Z band-like material, strongly supporting a variable degree ofmyofibrillar differentiation, were noted. Other features were leptofibrils, Z band streaming and hypertrophy,nemaline rods-like thickening of Z band, thick filaments whorling. Mitochondria displayed woollydensities, rods, cristae disorganization, vacuolization, vesicular cristae. As a conclusion, the ultrastructuralexamination confirmed the congenital dysplasia and severe degeneration of cardiac tissue and themyocardiocytes as cell of origin, as revealed by intercalated disks and tubular structures similar to Tsystem.[...]