Core／targetoid fiberとlobulated fiberを合併したnemaline myopathyの1例

A CASE OF NEMALINE MYOPATHY WITH CORE/TARGETOID FIBERS AND LOBULATED FIBERS

I．はじめに

　1963年，Shyら^22）は4歳のfloppy infantの筋生検で筋線維中央部に糸くず様の桿状物質（以下rod）を見い出し，"nemaline myopathy"として報告した。その後このようなrodを有し，臨床的にも特有な筋萎縮，筋力低下を呈する症例がnemaline myopathyとして多数報告され，また最近ではこのrodの本態についても種々の角度から検討が加えられつつある^23,24）。

　しかし，一方ではnemaline myopathyという名称そのものが主に筋組織の形態変化に基づいてつけられた疾患名であるため，それぞれの報告例では発症年齢や経過，遺伝形式も多様であり，その疾患特異性も問題となつてきている。

A case of nemaline myopathy is reported.

The patient was a 23-year-old man, born of consanguineous parents. His early milestones were reported to be normal. At the age of 10, bilateral pseudohypertrophies of gastrocnemius were indi-cated. He noticed abnormalities of walking at about the age of 14, followed by weakness of arms and legs. His disorder was slowly progressive. At the age of 15, he was diagnosed as limb-girdle type of muscular dystrophy.

He has a thin figure, high arched palate and scoliosis. Neurological examination revealed muscle weakness and atrophy, mainly involving the prox-imal and axial muscles. The deep tendon reflexeswere abscent. There were pes cavus bilaterally.

Serum creatine phosphokinase (CPK) activity was mildly raised at 330 units. In the electro-myogram, short duration potentials and sometimes high amplitude spikes were observed in the vastus lateralis muscle and biceps brachii muscle.

The vastus lateral muscle was biopsied. The muscle fibers ranged from 10 ,am to 90 μm in diameter. In trichromatically stained sections, collections of rods were seen in the subsarcolemmal and central regions of the muscle fibers and they were seen in mostly in type 1 fibers. In ATPase reacted sections, muscle showed type 1 fiber predominance. There were varieties of architectural changes of muscle fibers, namely core/targetoid fibers, lobulated fibers, moth-eaten or "increase-decrease" pattern by oxidative enzyme staining.

On EM most of the rods originated from the Z-band and were continuous to the thin filaments. Rod achieved a size up to 2.0 μm and showed a periodicity of parallel striation of about 100 Åand perpendicular striation of 120 Å, arranged in rec-tangular lattice. The targetoid regions revealed closely packed myofibrils and a marked reduction or abscence of mitochondria, glycogen particles and sarcotubules.

There are many reports suggesting neurogenic possibilities of nemaline myopathy. But some myogenic factors as well as neurogenic, in this case were indicated clinically and histologically.