Bovine generalized lipofuscinosis and sarcoplasmic inclusions: histopathological and histochemical features in three cases

Abstract

Three adult Holstein-Friesian dairy cows (4 to 6 years old) which had been raised at three different farms were culled with a long history of locomotor dysfunction attributed to dislocation or subluxation of the hip joint (two cows) or foot rot (one cow). They revealed dark brown discoloration of multiple sites of the carcasses at postmortem examination. On histopathological and histochemical investigations, lipofuscin pigments showing autofluorescence, sudanophilia, argyrophilia, periodic acid-Schiff (PAS) positiveness, and acid fastness were stored within otherwise normal cells of various sites in the body, including many thoracic and abdominal viscera, skeletal muscle, diaphragm, and tongue. In the central nervous system, some neurons with massive lipofuscin deposition were prominently shrunken but associated with neither necrotic changes nor glial reaction. Such a generalized pigmentary condition was distinguished from neuronal ceroid lipofuscinosis and thus was diagnosed as generalized lipofuscinosis. Furthermore, distinct proteinaceous eosinophilic inclusions were simultaneously observed to a varying degree within myofibers of the diaphragm, heart, rumen, or small intestine. These inclusions stained weakly positive with PAS and negative with Nile blue, Sudan black B, periodic acid-methenamine silver (PAM), and acid-fast stains. Autofluorescence was not seen. Staining properties demonstrated by phosphotungstic acid-hematoxylin (purple blue) and Masson's trichrome (bright red) stains were compatible with those of myofibrils, presumably suggesting that the inclusions have chemical composition similar or identical to that of myofibrils. It remains to be elucidated whether the occurrence of such sarcoplasmic inclusions was related to lipofuscinogenesis or a nonspecific phenomenon indicating an incidental finding.