Alaggio Rita, Ninfo Vito, Rosolen Angelo, Coffin Cheryl M
Department of Oncology and Surgery, Section of Pathology, University of Padova, Padova, Italy.
Am J Surg Pathol. 2006 Mar;30(3):388-94. doi: 10.1097/01.pas.0000190784.18198.d8.
Soft tissue sarcomas in the first year of life are rare, and the most common sarcomas in infancy are embryonal rhabdomyosarcoma, Ewing sarcoma/primitive neuroectodermal tumor, congenital infantile fibrosarcoma, and primitive sarcomas such as undifferentiated sarcoma. In this study, we report 6 cases of a primitive myxoid mesenchymal tumor of infancy (PMMTI), which previously may have been included under the diagnostic categories of congenital-infantile fibrosarcoma or infantile fibromatosis. PMMTI occurred in 6 infants, 3 of whom had a congenital presentation of a soft tissue mass. All patients were otherwise healthy. The tumors occurred on the trunk, extremities, and head and neck. Grossly, the tumors were nonencapsulated and had a multinodular appearance with focal infiltrative growth, a white fleshy cut surface, and a tumor diameter ranging from 2 to 15 cm. Histologically, a diffuse growth of primitive spindle, polygonal, and round cells occurred in a myxoid background. The tumor cells were arranged in a vaguely nodular pattern with peripheral collagenized stroma, higher cellularity at the periphery, and a delicate vascular network in the background. Immunohistochemically, the tumors displayed diffuse reactivity for vimentin and no reactivity for smooth muscle actin, muscle specific actin, desmin, S-100 protein, or myogenin. Electron microscopy documented a poorly differentiated fibroblastic proliferation. Four cases tested negative for the ETV6-NTRK3 gene fusion by RT-PCR. One tumor had a complex karyotypic abnormality with rearrangements involving chromosomes Y, 9, and 3. Three patients had recurrences or metastasis treated with a combination of surgery and chemotherapy. One patient is alive with persistent locally aggressive disease, 2 are alive with no evidence of recurrence, 1 had a recurrence treated surgically without further follow-up information, 1 patient died with persistent tumor and sepsis 6 weeks after diagnosis, and 1 patient was lost to follow-up. The morphologic appearance combined with the ultrastructural features and absence of the typical gene rearrangement of congenital-infantile fibrosarcoma are unique, and we propose that PMMTI represents a new category of pediatric fibroblastic-myofibroblastic tumor.
一岁以内的软组织肉瘤较为罕见，婴儿期最常见的肉瘤是胚胎性横纹肌肉瘤、尤因肉瘤/原始神经外胚层肿瘤、先天性婴儿纤维肉瘤以及未分化肉瘤等原始肉瘤。在本研究中，我们报告了6例婴儿期原始黏液样间叶性肿瘤（PMMTI），该肿瘤此前可能被归入先天性婴儿纤维肉瘤或婴儿纤维瘤病的诊断类别中。PMMTI发生于6名婴儿，其中3名婴儿先天性表现为软组织肿块。所有患者其他方面均健康。肿瘤发生于躯干、四肢以及头颈部。大体上，肿瘤无包膜，呈多结节状外观，有局灶性浸润性生长，切面为白色肉质，肿瘤直径为2至15厘米。组织学上，原始梭形、多边形和圆形细胞在黏液样背景中呈弥漫性生长。肿瘤细胞呈模糊的结节状排列，周边有胶原化的间质，周边细胞密度较高，背景中有纤细的血管网络。免疫组化显示，肿瘤对波形蛋白呈弥漫性反应，对平滑肌肌动蛋白、肌肉特异性肌动蛋白、结蛋白、S - 100蛋白或肌细胞生成素无反应。电子显微镜检查证实为低分化的成纤维细胞增殖。4例经逆转录聚合酶链反应检测ETV6 - NTRK3基因融合为阴性。1例肿瘤有复杂的核型异常，涉及染色体Y、9和3的重排。3例患者复发或转移，接受了手术和化疗联合治疗。1例患者存活，患有持续性局部侵袭性疾病；2例患者存活，无复发迹象；1例患者复发后接受手术治疗，无进一步随访信息；1例患者在诊断后6周因持续性肿瘤和败血症死亡；1例患者失访。其形态学表现、超微结构特征以及缺乏先天性婴儿纤维肉瘤典型的基因重排是独特的，我们提出PMMTI代表了一种新的儿童成纤维细胞 - 肌成纤维细胞肿瘤类别。
