Special techniques in diagnostic myopathology.

While muscle biopsy has been standardized since the introduction of electron microscopy, histochemistry, and morphometry into diagnostic myopathology, additional diagnostic techniques have recently been added. Immunomorphologic methods-firmly established in oncology long ago-are beginning to be applied in diagnostic myopathology. These methods concern the evidence of intermediate filaments in regenerating and denervated fibers as well as in certain myopathies marked by intermediate filament-related inclusions such as cytoplasmic bodies, spheroid bodies, or Mallory body-like inclusions. The connotation of the immunomorphologic approach is further emphasized by the discovery of dystrophin, a normal protein within muscle fibers which is deficient in Duchenne's and Becker's muscular dystrophies resulting in the now-standard examination of dystrophin in muscle biopsy specimens. It is to be expected that immunomorphologic techniques will rapidly develop further, depending on the isolation of muscle-and disease-specific proteins or defective proteins and the availability of antibodies against these proteins. It is conceivable that immunohistological diagnostic methods in myopathology may, one day, render currently established techniques obsolete.