[名词解释] 正中囊肿

圆柱瘤 引起低磷血症的常见病因是() ["A．磷向细胞外转移","B．PTH过度分泌","C．肠道磷酸盐的吸收减少","D．细胞外磷酸盐丢失","E．肾磷酸盐阈值降低"] 牙骨质瘤 杨梅状样血管瘤 恶性黑色素瘤()浆细胞肉瘤()恶性淋巴瘤()骨源性肉瘤()软组织肉瘤() ["A．起源间叶组织的恶性肿瘤","B．起源骨间质的恶性肿瘤","C．以颈部淋巴结最好发","D．局部剧烈疼痛为主要症状","E．周围可有卫星灶"] 正中囊肿