骨外骨肉瘤是一种罕见形式,它发生于与骨骼结构无任何联系的组织。本文报道一例71岁男性肝原发性骨肉瘤。病人因食欲减退、体重减轻、上腹包块、肠梗阻入院。血清硷性磷酸酶294单位/升。手术见肿瘤与十二指肠粘连,分离后连同肝左叶一并切除。病理:肿瘤位于肝叶内,是被大网膜包绕的圆形肿块,体积25×20×12cm,重3.4公斤。切面呈淡灰红色,易碎,有条索状出血及坏死。镜检:肿瘤主质由梭形细胞构成,呈编织,状排列,局部可见瘤巨细胞。核中度多形性含有粗颗粒染色质及核仁,核分裂常见,多为非典型核分裂。在细胞较丰富的区域,间质呈网状纤维网,局部有致密胶原,包绕瘤细胞的类骨组织及早期花边样矿质化散在于肿瘤各 Extra-osseous osteosarcoma is a rare form that occurs in tissues that are not associated with skeletal structures. This article reports a 71-year-old man with primary liver osteosarcoma. The patient was admitted to hospital because of loss of appetite, weight loss, upper abdominal mass, and intestinal obstruction. Serum alkaline phosphatase 294 units/L. The operation saw tumor and duodenal adhesions, and was removed together with the left hepatic lobe. Pathology: The tumor is located in the liver lobe and is a round mass surrounded by a large omentum, measuring 25 x 20 x 12 cm and weighing 3.4 kilograms. The cut surface is pale gray-red, brittle, with cord-like haemorrhage and necrosis. Microscopic examination: The main tumor is composed of spindle cells, which are braided and arranged in the shape of a giant tumor cell. The nuclear moderate polymorphism contains coarse-grained chromatin and nucleoli. Nuclear fission is common and mostly atypical nuclear division. In areas with rich cells, the interstitium is a reticular fiber network with dense collagen locally, and the bone-like tissue surrounding the tumor cells and the early lace-like mineralization scattered in the tumors.