骨良性间叶瘤亦称良性间充质瘤、间叶错构瘤 ,由分化好而成熟的多种间胚叶组织构成 ,发生于骨者极为罕见。今遇 1例 ,经手术及病理证实 ,报告如下。患者　女 ,2 2岁。 2年前偶然发现下腹部一约拳头大小肿块 ,近 1年肿块逐渐长大 ,伴有下腹部及骶臀部酸痛。体检 :下腹正中扪及一 Benign mesenchymal tumors, also known as benign mesenchymal tumors, mesenchymal hamartomas, consist of a variety of well-differentiated and mature mesodermal tissues, which are rare in bone. In this case, one case was confirmed by surgery and pathology. The report is as follows. Female patient, 2 2 years old. Two years ago, he found a small bump about the lower abdomen. He had a bump in his or her body in the last 1 year, accompanied by pain in his lower abdomen and her hips and hips. Physical examination: middle and middle of the lower abdomen