Transient cytoplasmic bodies in muscle of three infants with Werdnig-Hoffmann disease.

We present three instances in which cytoplasmic bodies in muscle fibers were associated with Werdnig-Hoffmann disease. The children presented within the first 6 weeks of life with clinical symptoms and laboratory studies indicative of infantile spinomuscular atrophy (ISMA). Initial muscle biopsies in each case revealed signs of muscle immaturity and cytoplasmic bodies but lacked features of denervation. Follow-up biopsies in 2 cases revealed changes typical of ISMA, but cytoplasmic bodies were no longer present. A follow-up biopsy was not available in the third child who also had a clinical course consistent with ISMA. We discuss the pathogenesis of cytoplasmic bodies and their significance in association with Werdnig-Hoffmann disease.