[Muscle biopsy : Indications and techniques]

Various histological techniques were introduced for the analysis of muscle biopsy specimens in recent decades. During the 1960s, cryosections and enzyme histochemistry were established as the main techniques for evaluating muscle biopsies. Subsequently, immunohistochemistry was able to show normal components of muscle fibre, its damage, as well as accumulation or maldistribution in the presence of myopathies. In this way, structure myopathies, muscle dystrophies and inflammatory myopathies can be reliably diagnosed today. For the diagnosis of certain entities, semithin sections and electron microscopy of resin-embedded tissue, as well as molecular pathological techniques including immunoblotting and PCR are useful. To apply these and other methods optimally with the goal of achieving a diagnosis some prerequisites need to be met: a moderately affected muscle has to be chosen and a 3x1x1 cm biopsy should be taken by an experienced surgeon in an atraumatic way and transported immediately in a moist chamber to the nearest specialized laboratory. The muscle specimen is divided into four pieces, two of which are snap frozen in liquid nitrogen (one with OCT mounting medium on a cork plate, the other without mounting medium); the third piece is fixed in formalin and embedded in paraffin. The fourth is fixed in glutaraldehyde and embedded in resin. The logistical problems of a muscle biopsy need to be solved between clinicians and the analysis center prior to removal.