Histiocytoid cardiomyopathy of infancy: an unexplained myofibre degeneration.

An unusual multifocal degeneration of the myofibres of all chambers and the conducting system of the heart was found in a 4-month-old female in whom ventricular pre-excitation (Wolff-Parkinson-White syndrome) had been demonstrated. There was a complex malformation of the brain with hydrocephalus and bilateral corneal opacities and microphthalmos. The affected myofibres had a swollen vacuolated or granular cytoplasm and rounded nuclei giving a histiocytoid appearance. Disruption of myofibrils and gross dilation and disorganization of mitochondria were the major fine structural features. Reports of similar lesions in 8 other young female children are reviewed. 'Histiocytoid cardiomyopathy' is the term preferred over others which refer to an increased lipid content. The aetiology is unknown.