Delaporte C, Drouin F, Ract A R, Varet B, Fardeau M
Rev Neurol (Paris). 1985;141(2):109-19.
Diffuse skeletal muscle enlargement appeared in a 62 years old male without any detectable endocrine disturbance. The patient's weakness contrasted with his athletic appearance. There was no myotonia nor fasciculations. The laboratory investigations were unrevealing until 18 months after the apparent beginning of the disease: free kappa light chains in serum and urine and plasmocytosis in the bone marrow established the diagnosis of multiple myeloma. No amyloid infiltration was observed on the biopsied tissues: skin, muscle and tongue. The diameters of the muscle fibers were at the upper limit of the normal range. There was no fiber type grouping. Kappa light chain deposits surrounding the muscle fibers and numerous coated vesicles beneath the sarcolemmal membrane were found by electron microscopy. The patient's serum was tested on human muscle cell cultures and displayed trophic properties for these cells. This effect was not due to an acceleration of the myoblast proliferation, but to an enhancement of their differentiation. The fusion was more rapid than in presence of control serum and lead to larger and highly branched myotubes. Protein synthesis was increased as demonstrated by the significantly higher 3H-leucine incorporation into the trichloroacetic-acid precipitable material. An identical trophic effect was also found with the kappa light chains purified from the patient's serum but only in the presence of normal human serum.
一名62岁男性出现弥漫性骨骼肌增大，未检测到任何内分泌紊乱。患者的虚弱与其健壮的外表形成反差。无肌强直和肌束震颤。直到疾病明显开始18个月后，实验室检查才有所发现：血清和尿液中的游离κ轻链以及骨髓中的浆细胞增多确诊为多发性骨髓瘤。在活检组织（皮肤、肌肉和舌头）中未观察到淀粉样蛋白浸润。肌纤维直径处于正常范围上限。无纤维类型分组。通过电子显微镜发现肌纤维周围有κ轻链沉积，肌膜下有大量被膜小泡。对患者血清在人肌肉细胞培养物上进行检测，显示对这些细胞具有营养特性。这种作用并非由于成肌细胞增殖加速，而是由于其分化增强。融合比在对照血清存在时更快，导致形成更大且高度分支的肌管。如显著更高的3H-亮氨酸掺入三氯乙酸可沉淀物质所示，蛋白质合成增加。从患者血清中纯化的κ轻链也发现了相同的营养作用，但仅在正常人血清存在的情况下。
