Cardiac rhabdomyoma in a slaughtered pig / Rabdomioma cardíaco em um suíno de abate

Rhabdomyoma is a rare neoplasm of striated muscle that occurs predominantly in the myocardium. In animals, cardiac rhabdomyoma are observed as incidental lesions in slaughter pigs and have been rarely described in other species, such as cattle, dogs, and deer. This report describes a case of cardiac rhabdomyoma in a male pig at slaughter age that died suddenly in the pre-slaughter period. At necropsy, multiple nodules were observed in the right and left ventricular walls and the interventricular septum. Histopathological examination showed neoplastic proliferation composed of polyhedral cells, with vacuolated cytoplasm that sometimes presented a spider cell appearance. Histochemical staining with Schiffs periodic acid revealed glycogen granules in the cytoplasm of neoplastic cells. The neoplastic cells were positive for desmin, neuron-specific enolase, atrial natriuretic peptide, and vimentin by immunohistochemistry, to varying degrees. The anatomopathological and immunohistochemical findings observed in this case confirmed the diagnosis of cardiac rhabdomyoma, possibly originating from the Purkinje fibers.(AU)

Rabdomioma é um neoplasma raro de músculo estriado que ocorre predominantemente no miocárdio. Em animais rabdomiomas cardíacos são observados como lesões incidentais em suínos de abate, raramente descrito em outras espécies como bovinos, cães e cervos. Neste relato descreve-se um caso de rabdomioma cardíaco em um suíno, macho, em idade de abate que morreu subitamente no período pré-abate. Na necropsia visualizou-se múltiplos nódulos nas paredes ventriculares direita e esquerda, e septo interventricular. O exame histopatológico mostrou proliferação neoplásica composta por células poliédricas, com citoplasma vacuolizado que por vezes apresentavam aspecto de célula de aranha. Na coloração histoquímica de ácido periódico de Schiff evidenciaram-se grânulos de glicogênio no citoplasma das células neoplásicas. As células neoplásicas foram imunorreativas na imuno-histoquímica para desmina, enolase neurônio específica, peptídeo natriurético atrial e vimentina em diferentes graus. Os achados anatomopatológicos e imuno-histoquímicos observados neste caso confirmam o diagnóstico de rabdomioma cardíaco, possivelmente com origem das fibras de Purkinje.(AU)

Cardiac rhabdomyoma in a slaughtered heifer

During routine inspection of a slaughtered heifer from a feedlot, the veterinarian in charge condemned the heartdue to a lesion on the endocardium. Histopathology and immunohistochemistry showed that the lesion was composed bycardiac tissues at different degree of differentiation, disordered and out of proportion. The most conspicuous was adispersed population of large, vacuolated and PAS positive cells, enmeshed in excessive fibrous connective tissue. Thesecells, identified as spider cells, resulted markedly positive for desmin, and negative for vimentin, smooth muscle α-actin andmyogenin factor 4. An extensive infiltration by fibro-fatty tissue was other abnormal component of the lesion. Furthermore,abnormal cardiomyoblasts forming tortuous bundles were also recognized. Nonetheless, these cells showed distinctivestriations and even intercalated discs. Some of this abnormal cardiac myoblasts resulted markedly positive for desmin andisolated strands also were positive for smooth muscle α-actin, but negative for myogenin factor 4 and vimentin. Based onthe pathognomonic spider cells and immunoreactivity, the lesion was classified as a cardiac rhabdomyoma. For some, thecardiac rhabdomyomas are not true neoplasms but congenital hamartomas in heart. However, principal component incardiac hamartomas in animals is an abnormal vascular pattern completely different from the lesion herein presented. Basedon the diverse tissue components, their immature and distorted image and, positive results for immunomarkers of earlymyoblast differentiation as well as terminal cardiomyocyte characteristics, dysplasia must be considered as the commondenominator in development of cardiac rhabdomyomas with tissue heterogeneity.(AU)

Cardiac rhabdomyoma in a slaughtered heifer

During routine inspection of a slaughtered heifer from a feedlot, the veterinarian in charge condemned the heartdue to a lesion on the endocardium. Histopathology and immunohistochemistry showed that the lesion was composed bycardiac tissues at different degree of differentiation, disordered and out of proportion. The most conspicuous was adispersed population of large, vacuolated and PAS positive cells, enmeshed in excessive fibrous connective tissue. Thesecells, identified as spider cells, resulted markedly positive for desmin, and negative for vimentin, smooth muscle α-actin andmyogenin factor 4. An extensive infiltration by fibro-fatty tissue was other abnormal component of the lesion. Furthermore,abnormal cardiomyoblasts forming tortuous bundles were also recognized. Nonetheless, these cells showed distinctivestriations and even intercalated discs. Some of this abnormal cardiac myoblasts resulted markedly positive for desmin andisolated strands also were positive for smooth muscle α-actin, but negative for myogenin factor 4 and vimentin. Based onthe pathognomonic spider cells and immunoreactivity, the lesion was classified as a cardiac rhabdomyoma. For some, thecardiac rhabdomyomas are not true neoplasms but congenital hamartomas in heart. However, principal component incardiac hamartomas in animals is an abnormal vascular pattern completely different from the lesion herein presented. Basedon the diverse tissue components, their immature and distorted image and, positive results for immunomarkers of earlymyoblast differentiation as well as terminal cardiomyocyte characteristics, dysplasia must be considered as the commondenominator in development of cardiac rhabdomyomas with tissue heterogeneity.