软组织透明细胞肉瘤的研究进展

Advances in research of clear cell sarcoma of soft tissue

透明细胞肉瘤(clear cell sarcoma of soft tissue,CCS)是一种较少见的软组织肿瘤,多发于青少年及中年,以四肢远端的深部软组织多见,常与肌腱和腱膜相毗邻,易复发和转移。组织来源尚未明确。起病隐匿,肿瘤较大时可引起疼痛和压痛。大体为无明显包膜,呈分叶状或多结节状切面灰白色的肿块。组织学特点为细胞多角形或梭形,成巢状排列其间有纤维组织分隔。超微结构显示,胞质内可见黑色素颗粒;免疫组化S-100、HMB-45、Vi mentin及MITF阳性。CCS中特异表达的EWS/ATF1融合基因在血管瘤样纤维组织肉瘤(angio-matoid fibrous histiocytom,AFH)中也表达。RT-PCR检测MITF可鉴别CCS和AFH两种软组织肉瘤。BREF基因是否发生突变对CCS与原发部位不明确的恶性黑色素瘤的鉴别诊断有很大意义。治疗仍以手术切除为主,预后较差。

Clear cell sarcoma （CCS） is a rare malignant tumor of soft tissue. It occurs preferentially in adolescents and young adults. CCS shows a predilection for the deep soft tissues of the lower extremities close to the tendon and aponeuroses and is associated with a high propensity of local recurrence and distant metastases. The histogeneous source is uncertain. CCS occurs without any significant clinical symptom and the larger tumor can result in pain and tenderness. Naked eye of the tumor shows obsolete envelope and lobulated or multinodular gray ＂tumor. Histopathologically, nests for polygonal or fusi form cells and the cellular aggregates are encased by delicate fibrous septa. Ultrastructural examination reveals that the majority of CCS contains melanosomes. The immunochemistry is positive or partially positive for markers of S-100, HMB-45, Vimentin and MITF. The fusion gene EWS/ATF 1 is characteristic but not entirely unique for CCS （similar fusion genes are aiso seen in angiomatoid fibrous histiocytoma）. The detection of microphthalmia-associtated transcription factor （MITF） by RT PCR in CCS is valuable for differential diagnosis with AFH. BREF gene mutations or not can clearly distinguish CCS from metastatic malignant melanoma with an unknown primary site. Complete surgical removal is the best treatment and the prognosis is relatively poor.