Use of different histomorphometric parameters in the routine assessment of human skeletal muscle biopsies

In the diagnosis of muscle biopsies it has become traditional to identify any changes in fibre size by measuring minimum fibre diameter (dmin), as past technical constraints prevented the routine measurement of other parameters. The advent of user-friendly computerised image analysis, however, has facilitated such measurements. We examined a total of 39 skeletal muscle biopsies, including normal, myopathic, myositic and neuropathic cases, to determine whether improved discrimination between normal and abnormal histology was now possible on the basis of fibre cross-sectional areas (CSA). Using a semi-automated image analysis system, measurements of dmin, CSA and fibre perimeter were made. In all case groups, the skew of the frequency distribution of area was greater than that of dmin, moreover the difference was more marked in the abnormal cases. As expected, the mean values of dmin and area were reduced in all abnormal cases. As expected, the mean values of dmin and area were reduced in all abnormal cases. The range of their values, however, was reduced in the myopathic and neuropathic cases and increased in the myositic cases. In conclusion, fibre area is a more valuable discriminator between normal and abnormal skeletal muscle than is dmin.