[A case of HTLV-1 associated myelopathy and adult T-cell leukemia, presenting unique muscle pathology including rimmed vacuole].

A 63-year-old man developed muscular atrophy and weakness in his four extremities since 1983, and was pointed out to have smoldering ATL by elevated HTLV-1 antibody titers in the serum (x 2,500) and CSF (x 32) in 1985. Neurological examinations revealed proximal muscular weakness and atrophy of four extremities, and mild spasticity of both legs. Deep tendon reflexes were hypoactive in both arms and hyperactive in both lower extremities with ankle clonus and bilateral positive Babinski and Chaddock reflexes. These findings were compatible with HAM. His gait, however, was markedly waddling, requiring support. Muscle biopsy at left biceps muscle revealed inflammatory change with rimmed vacuoles, small group atrophy, and marked type 1 fiber predominance. These findings on muscle biopsy are different from those of previously reported cases with HAM, showing some similarities to inclusion body myositis or distal myopathy with rimmed vacuole.