Although skeletal muscle mass decreases with aging, its decrease rate may differ among parts of the body. There have been few studies examining the differences in the muscle mass decrease rate between proximal and distal parts of the limbs or between the left and right legs in a large population. Bioelectrical impedance (BI) index, calculated as the ratio of the square of segment length to impedance, is linearly correlated with the muscle mass calculated by MRI (r=0.902-0.976, p<0.05, Miyatani et al., 2001) in the limb segments. The purpose of this study was to examine differences in the decrease rate of muscle mass between the proximal and distal parts of the limbs and between the upper and lower limbs in healthy Japanese. The BI index was measured in the bilateral thighs, lower legs, upper arms, and forearms of 1006 healthy Japanese men and women (aged 15-97 years). While the BI index decreased with aging in all examined parts of the body, the decrease rate was larger in the lower limb than in the upper limb, and in the thigh than in the lower leg. The percentage of people who showed a difference of more than 10 % in the BI index between the left and right lower limbs was significantly higher in the elderly than in young subjects. These differences in the decrease rate of muscle mass between limbs may be associated with decreases in physical functions in the elderly.

A 78-year-old woman who had a history of left deep venous thrombosis was referred to our hospital with a sudden hemoptysis. Thoracic computed tomography showed a solitary pulmonary nodule in the right lower lobe. Based on her medical history of deep venous thrombosis, she was tentatively diagnosed as having pulmonary embolism and successfully treated by inserting an inferior vena cava filter and anticoagulant therapy with warfarin [Please confirm whether previous sentence is correct]. However, the lung nodule on thoracic computed tomography was still depicted four months later. With suspicion of a malignant tumor, including possible lung cancer, a right segmentectomy was performed. Pathological assessment of the resected specimen showed the tumor was derived from the right bronchial wall, but was not ruptured into the intratracheal lumen, as well as coexistence with intraalveolar hemorrhage near the tumor. The lung nodule was diagnosed as bronchial schwannoma. Thus, the origin of the hemoptysis was found to be pulmonary embolism due to deep vein thrombosis, and not by bronchial schwannoma, which was also present in the lung.