Nemaline myopathy with intranuclear rods--intranuclear rod myopathy

Among the different nosological forms of nemaline/rod myopathy, one morphological variant is marked by intranuclear rods in addition to sarcoplasmic rods. Such patients fall into two categories: firstly, adults and secondly, young infants suffering from the severe form. Intranuclear rods indicate unfavourable prognosis. Recently, intranuclear rods without sarcoplasmic rods have also been encountered. Intranuclear rods, largely solitary, are often found large in size with the ultrastructural lattice pattern of sarcoplasmic rods and Z-disks. They contain alpha-actinin and actin. The origin of intranuclear rods is still enigmatic. Their presence within nuclei without sarcoplasmic rods points to a de novo formation within the respective muscle fiber nuclei.