8例外周性原始神经外胚层肿瘤的病理、CT、MRI表现并文献复习

CT,MRI and Pathologic Features of Peripheral Perimitive Neuroectodermal Tumors:A Report of Eight Cases with Literature Review

背景与目的:外周性原始神经外胚层肿瘤(primitive neuroectodermal tumor,pPNET)罕见。本研究目的是分析外周性PNET的影像学及病理学表现,以提高对本病的认识。方法:回顾性分析有完整影像学资料及经病理证实的8例PNET。结果:1例病灶位于上颌窦,1例位于鼻旁,1例位于肩颈部,2例位于胸腔,2例位于纵隔,1例位于骶尾部臀大肌。本组病例均表现为软组织肿块,CT显示病灶范围大、边界不清,密度不均匀且伴坏死囊变,部分病灶内有沙砾样钙化,增强后呈不均匀强化。软组织肿块侵蚀临近骨质时表现为溶骨性骨质破坏。在MRI SE T1WI上表现为等或低信号,T2WI上表现为不均匀高信号,部分病例可见假包膜或分隔样改变。病理形态上Homer-Wright菊形团为其特异性表现,免疫组织化学结果,肿瘤均表达CD99,3例检测NSE和VIM者结果均呈阳性,5例检测CK者结果均呈阴性,并且不表达白细胞共同抗原(LCA)等。结论:pPNETs的病理及免疫组化可提供诊断依据。pPNETs的CT与MRI缺乏特征性表现,但能较好的显示肿瘤的内部结构、明确肿瘤的范围,有助于指导制定治疗方案和评价治疗效果。

BACKGROUD ＆ OBJECTIVE： Peripheral primitive neuroectodermal tumor （pPNET） is very scarce. This study was to analyze the imaging and pathologic features of pPNET. METHODS： Computed tomogram （CT） and magnetic resonance image （MRI）, and pathologic reports of 8 pPNET patients were analyzed. RESULTS： Of the 8 cases, 1 lesion located at the maxillary sinus, 1 near to the nose, 1 at the shoulder and neck, 2 in the chest, 2 in the mediastinum, and 1 in the sacrococcygeal gluteus maximus. All lesions were soft tissue masses. CT images revealed that all lesions were huge and inhomogeneous, with unclear border and were accompanied with cystis degeneration. Gravel-like calcifications were detected in some lesions that showed heterogeneous enhancement after contrast. Osteolytic bone destruction was observed when the soft tissue mass invaded the adjacent bones. T1-weighted image showed low or equal signal, and T2-weighted image showed uneven high signal. Some lesions showed false capsule and separating changes. Homer-Wright daisy-group was a specific pathologic feature of pPNETs. According to Immunohistochemical results, CD99 was positive in all lesions, neurone specific enolase （NSE） and vimentin （VIM） were positive in all the 3 detected lesions, cytokeratin （CK） and leucocyte common antigen （LCA） were negative in all the 5 detected lesions. CONCLUSIONS： The pathologic and immunohistochemical determinations can provide diagnostic references for pPNETs. Although the manifestations of pPNETs on CT and MR images are not specific, these two methods can show the internal structure of tumors and help to define their scope, which are helpful in determining treatment strategy and evaluating therapeutic effects.