Congenital Multifocal Increase of Purkinje Fibres in a Calf with Cardiac Conduction Delay

SummaryA female 4-month-old Holstein–Friesian calf was presented in heart failure. Microscopical examination of samples of the cardiac wall taken at necropsy examination revealed numerous aggregates of Purkinje fibres, particularly in the perivascular areas. Some Purkinje fibres were stained strongly with phosphotungstic acid haematoxylin and immunohistochemically were shown to express alpha smooth muscle actin, indicating an embryonic-like Purkinje fibre phenotype. A diagnosis of congenital multifocal increase of Purkinje fibres was made. The histological features of this case resemble multifocal cardiac Purkinje cell tumour of the heart in man.