Congenital myopathies with inclusion bodies: a brief review

Based on morphological abnormalities, congenital myopathies can be classified into several categories: (1) enzyme histochemically abnormal appearance without structural pathology, e.g., congenital fibre type disproportion or congenital fibre type uniformity; (2) abnormally placed nuclei, e.g. myotubular and centronuclear myopathies; (3) disruption of normal intrinsic structures, largely sarcomeres, e.g. central cores and minicores; (4) abnormal inclusions within muscle fibres. Several such inclusions are derived from pre-existing structures, most notably rods or nemaline bodies. Other derivatives of Z-band material are cytoplasmic bodies and possibly related inclusions as spheroid bodies, sarcoplasmic bodies or Mallory body-like inclusions. These inclusions share accumulation of desmin, the muscle fibre-specific intermediate filament, and of other proteins, some of them physiological, but others quite abnormal. Inclusions without identified precursors are fingerprint bodies, reducing bodies, cylindrical spirals, and Zebra bodies. Experimental models and tissue culture reproduction are necessary to further clarify significance of these inclusions in congenital myopathy pathology.