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Table 4 Histological changes in the 32 Hungarian Vizslas with biopsy-confirmed polymyopathy

From: Clinical features of idiopathic inflammatory polymyopathy in the Hungarian Vizsla

Histopathological changes (Total 32) Group 1 Group 2
25 total dogs (biopsies) (confirmed VIP diagnosis) 7 dogs (3 biopsies, 1 biopsy and post-mortem/3 post-mortem) (myopathy diagnosis)
Inflammatory change e.g. Lymphohistiocytic inflammation Variability in myofibres size with multifocal endomysial, interstitial and perivascular mononuclear cell infiltrations (lymphocytes & macrophages +/− plasma cells, eosinophils) of non-necrotic fibres. Underlying inflammatory process masked by corticosteroid treatment in one case.  
25 dogs 0 dogs
Myopathic change   Variation in the myofibre size without inflammatory infiltration.
0 dogs 7 dogs
Adipose tissue Small amount of adipose tissue associated with fibrosis. Adipocytes present in some fascicles (endomysium and perimysium).
2 dogs 1 dogs
Fibrosis None OR perimisial/endomysial fibrosis OR occasionally area of fibrosis with lack of myofibres with any significant inflammation (primary or secondary?)  
3 dogs 0 dogs
Degenerative changes Either any appreciable myofibre degeneration or active degenerative changes within the muscle fibres (variation in myofibre diameter, atrophy with round to polygonal/angular shape, hyalinisation, nuclear internalisation, sarcolemmal fragmentation). Variation in muscle fibres, atrophy (occasionally smaller fibres grouped together, some angular but most round to polygonal profile), nuclear internalisation.
19 dogs 4 dogs
Regenerative changes Nuclear rowing, centralisation/hyperthrophy of the nuclei increased cytoplasmic basophilia, type 2 fibres. Occasional enlarged and round myofibres (compensatory hypertrophy), and nuclear rowing.
13 dogs 3 dogs
Necrotic fibres Scattered to severe necrotic myofibres with some undergoing phagocytosis.  
7 dogs 0 dogs
Fibrosis Mild to moderate endomysial and perimysial fibrosis secondary to myofibre loss. Increased endomysial and perimysial connective tissue secondary to myofibre loss.
7 dogs 2 dogs
Intramuscular nerve branches Normal (25 dogs) Normal (7 dogs)
Immunoreagent SPA-HRPO Present in two cases  
(Antibodies against endplate proteins)
Dystrophin protein   Decreased staining for carboxy terminus of the dystrophin protein was found in one case; however, the dog improved on immunosuppressive treatment and the suspicion for muscle dystrophy was abandoned.