婴儿恶性横纹肌样瘤病理特征及临床预后探讨

目的 探讨婴儿恶性横纹肌样瘤(MRT)临床病理特征、诊断及治疗预后.方法 收集我院2009年1月至2014年12月间病理诊断为MRT 5例患儿的临床资料、常规组织切片及免疫组化切片,显微镜下观察及追踪随访.结果 5例患儿就诊年龄1～330 d,平均70 d;男∶女为3∶2;肿瘤发生于肾1例、皮肤软组织4例;临床肿瘤分期Ⅰ期1例,Ⅳ期4例.5例患儿均接受了局部扩大切除及周围淋巴结清扫术,其中发生于颈部和大腿的3例手术时肿瘤细胞已侵及周围组织,脉管内查见转移瘤栓,临床肿瘤分期均处于Ⅳ期,放弃治疗术后5～7 d复发,存活14～28 d,平均21 d;发生于肾的1例手术时肾皮质静脉内见瘤栓,CT提示双肺多发转移结节,临床肿瘤分期为Ⅳ期,化疗5个疗程后CT提示肺转移灶扩大,术后存活180 d;发生于会阴皮肤的患儿1例手术时肿瘤细胞未侵及周围扩大切除的组织,淋巴结内未见转移,脉管内未见瘤栓,临床肿瘤分期为Ⅰ期,术后未化疗,随访3年无复发和转移,生存良好.4例Ⅳ期MRT患儿术后半年内病死率为75％(3/4),1年内病死率为100％.免疫组化肿瘤细胞胞浆强表达Vimentin,灶状表达CK、EMA,不表达INI1.结论 MRT具有进展快、侵袭性强、易复发和转移、预后差的临床特点,具有独特的病理组织学特征,患儿病死率与肿瘤分期直接相关,肿瘤分期越高,术后1年内病死率越高.肿瘤处于Ⅰ期的患儿完整切除有较长的生存期,处于Ⅳ期的患儿即使完整切除后辅以强力的化疗生存期仍很短.

Pathological characteristics and prognosis of malignant rhabdoid tumor in infants

Objective To explore the clinicopathological characteristics,diagnosis,treatment and prognosis of malignant rhabdoid tumor (MRT) in infants.Methods The clinical data,histopathological and immunohistochemical examinations were analyzed for 5 MRT patients from January 2009 to December 2014.Results There were 3 boys and 2 girls with an average age of 70 days.And the diagnostic time was 1 day to 330 days.Tumors were detected in kidney (n =1) and skin soft tissue (n =4).The neoplastic stages were Ⅰ (n =1) and Ⅳ (n =4).All of them underwent local wide resection with regional lymph node dissection.Tumors had infiltrated the surrounding tissue with intravascular tumor emboli in 3 patients.Classified as stage Ⅳ,they abandoned treatment,recurred at Day 5-7 and died at Day 14-28 post-operation.And the average age was 21 days.In one patient with renal MRT,intravascular tumor emboli were detected intraoperatively in renal cortex and multiple pulmonary tumor nodules visualized on computed tomography (CT).Tumor was classified as stage Ⅳ.After 5 cycles of chemotherapy,metastatic lung tumor expanded.This patient survived for 6 months postoperatively.In another patient with perineal MRT,tumor showed no invasion into the surrounding tissue and no intravascular emboli and it was classified as stage Ⅰ.Without chemotherapy,this patient survived without recurrence or metastasis up to 3 years postoperatively.Among 4 cases of stage Ⅳ MRT,75％ (3/4) died within 6 months and 100％ within 1 year postoperatively.The mortality rate rose with the stage of tumor.The histological characteristics of MRT were rhabdoid cells with eosinophilic cytoplasm often containing hyaline inclusions,eccentric oval nuclei and prominent nucleoli.Immunohistochemically,vimentin,CK and EMA were positive while INI1 was negative.Conclusions As a rare highly aggressive malignancy in young children with early metastasis and recurrence,MRT is usually in advanced stage at the time of diagnosis and its outcomes are poor.Early total resection often yields a longer survival.