Abstract
Two siblings with congenital myopathy without specific cytoarchitectural features such as nemaline myopathy, central core disease, myotubular myopathy, etc. were subjected to clinical and histopathologic examinations. Their clinical symptoms included early onset of proximally dominant mucle wasting and weakness, noticeable contractures of joints since infancy, myopathic electromyogram and slightly elevated serum creatine phosphokinase, but without central nervous system manifestation and facial muscle involvement. Although a number of cases of congenital muscular dystrophy (CMD) associated with mental retardation and facial muscle involvement (Fukuyama type CMD) have been reported, patients of congenital myopathy lacking such peculiar symptoms seem to be rare in Japan.
Case 1 (8 year-old boy): He was born at full term pregnancy with an uneventful delivery. His developmental milestones were slightly delayed; he sat with assist of his arms at 7 months, and learned to walk using brace at 15 months of age when he was already noted to have remarkable waddling gait and lumbar lordosis. He developed acute encephalopathy of unknown etiology at the age of 5 years, then he failed to walk and stand without support. On physical examination, he had severe generalized muscle wasting and weakness, and contractures of joints involving spine, hip, hands, fingers and ankle joints.
The muscle biopsy was performed from the rectus femoris at 3 years of age. The formalin-fixed and paraffin-embedded specimen demonstrated mild variation in muscle fiber size in association with scattered several “opaque” fibers and focal phagocytosis.
Case 2 (6 year-old girl, sister of Case 1): Her muscle weakness and hypotonia were much more remarkable in comparison with those of her brother. She was hypotonic since birth with a marked delay in developmental milestones. She started to crawl or shuffle at the age of 11 months, but she did not obtain standing or walking ability at all.
The biopsied muscle from the rectus femoris was stained with H & E, modified Gomori's trichrome, and a battery of histochemical methods including PAS, oil red 0, menadione-linked alphaglycerophosphatase, NADH-TR, ATPase with preincubation at pH 9.4, 4.6 and 4.2, phosphorylase and nonspecific esterase. There was marked variation in fiber size with severe fibrous as well as adipose tissue replacement, representing advanced myopathic changes. No evidence of metabolic muscle disorders was recognized on histochemical examination. However, type 2 fiber predominance (95%) and areas of type 2 fiber grouping suggested the possibly coexisted neural influence on the basic myopathic process.
