Cystic fibrosis and myocardial fibrosis [letter].

We were interested in the case reported by Mukherji et al., which 
suggested that cystic fibrosis might be an acid mucopolysaccharidosis. We have 
seen a similar child. Aged 5 years he was admitted to 
hospital with pneumonia. In spite of conventional treatment with cloxacillin and 
colistin he collapsed and died 48 hours after admission. The heart 
was not enlarged, but the myocardium showed a grossly abnormal appearance 
with variations in thickness and extensive areas of firm pale tissue. 
Histology of the heart muscle showed very dramatic changes with severe 
replacement fibrosis distributed patchily through the myocardium. This similar mixture of 
neutral and acid mucopolysaccharides was shown in both the pancreas and 
the salivary glands. There have now been a number of reports 
of myocardial fibrosis complicating cystic fibrosis. The case reported by Mukherji 
et al. and this case are the first in which mucopolysaccharide 
deposits have been found in the myocardium. The mixture of neutral 
and acid mucopolysaccharides in our case does not support the hypothesis 
that cystic fibrosis is simply a genetic acid mucopolysaccharidosis. 