Tre casi atipici di miopatia lipomatosa in bovine di razza piemontese:reperti anatomo-istopatologici

This study describes macroscopical and histological features of three cases of lipomatous myopathy (substitution of muscle tissue with adipose tissue) in Piedmontese cows. Several muscle samples, frozen in isopentane cooled using liquid nitrogen, were submitted to histological investigations. Slide sections (10 μm thick) were obtained using a cryostat and stained by the following histological and histochemical techniques: haematoxylin and eosin (H&E); modified Gomori trichrome; periodic acid–Schiff (PAS); red Oil stains, Sudan black, Sudan III, Cytochrome C oxidase (COX); succinate dehydrogenase (SDH), and reduced nicotinamide adenine dinucleotide–tetrazolium reductase (NADH-TR). Immunohistochemical stainings were also made employing specific antibodies to characterize the inflammatory cells. Gross pathology showed a different grade of infiltration of adipose tissue involving multiple or single muscles. Morphological staining revealed an infiltration of adipose tissue varying in distribution and severity, changes in muscle fiber size, and increased numbers of fibers with centrally located nuclei suggesting muscle degeneration-regeneration. Necrosis and non suppurative inflammatory cells were also seen. Furthermore, proliferation of connective tissue and non-specific myopathic changes, were present too. Histochemical stains confirmed this fat deposition but didn’t reveal metabolic changes in affected muscles. Sporadic focal immunopositivity for CD79, CD8, CD4 and MCHI were detected. Common usage of the world myopathy is restrict to describe a disorder of muscle generally characterized by different grade of degeneration of muscle fibers and high serum level of muscle enzymes. Myopathy are divided into several entities, such as diseases of the lower motor neuron, dystrophies, congenital myopathies, nutritional myopathies, metabolic and endocrine myopathies, inflammatory myopathies, and a miscellaneus group. Similarly to humans the classification of myopathies in animals is subject to modification based on findings of on-going genetic and pathogenetic studies as well as on changes in disease definitions. Vascular factors and neurogenic causes seem not involved in the pathogenesis of these cases of lipomatous myopathy. In next step the authors will delve into the role of genetic factors.