Abstract
A new clinical entity under the name of "juvenile muscular atrophy of unilateral upper extremity" was first described in 1959. Although about 150 cases in Japan, and several additional cases in other countries, have been clinically reported in the literature, the pathology has remained unknown because of the benign course of the disease. The first necropsy findings are reported, obtained from a patient with this disease, who died of lung cancer at the age of 38, 23 years after the onset of the disease. The lesions existed only in the anterior horns of the spinal cord at C5 approximately T1, particularly marked at C7 and C8, showing shrinkage and necrosis, degeneration of various degrees of large and small nerve cells, and mild gliosis. The pathological findings differ from those of reported cases of spinal vascular disorders, but some circulatory insufficiency in the territory of the spinal cord would seem to be suggested, although the underlying aetiology remains unknown.