Objective: To investigate the imaging appearance of CT and MRI in retroperitoneal dedifferentiated liposarcoma (DDL) based on pathological findings. Methods: Twelve patients with retroperitoneal DDL (13 lesions) who were surgically and pathologically confirmed were retrospectively collected in the Cancer Hospital of Chinese Academy of Medical Sciences. The correlation of CT and MRI features with histopathologic findings was analyzed. Results: The CT and MRI images of retroperitoneal DDLs were large, heterogeneous soft-tissue masses, mostly lobulated (30.8%, 4/13) or multinodular (46.2%, 6/13), invading adjacent anatomic structures (46.2%, 6/13). The lesions contained different proportions of fatty and non-fatty components, and usually with clear boundaries. The CT images of dedifferentiated components showed non-fatty masses of soft tissue density or mixed density, among which ground-glass nodules may be related to mucinous components. Occasionally calcification or ossification was seen (45.5%, 5/11). The contrast-enhanced CT and MRI images of non-fatty components commonly showed intense heterogeneous enhancement (84.6%, 11/13), central cystic changes and necrosis (61.5%, 8/13), pathologically corresponding to multiple types of soft tissue sarcomas without significant specificity. The well-differentiated components were fatty masses with irregular fibrous septa or soft tissue nodules, which is pathologically corresponding to well differentiated liposarcoma. Lymph node or distant metastasis was rare. Conclusions: The imaging manifestations of retroperitoneal DDLs are diverse and closely related to the proportion and distribution of different components. CT, MRI and contrast-enhanced imaging has a certain diagnostic value for retroperitoneal DDLs.
目的： 探讨腹膜后去分化脂肪肉瘤(DDL)的CT和磁共振成像(MRI)影像学表现，并与病理对照分析其诊断价值。 方法： 收集在中国医学科学院肿瘤医院就诊并经手术病理证实的12例腹膜后DDL患者(13个病灶)的临床资料，回顾性分析其CT和MRI影像学特点，并与病理结果对照判断其诊断价值。 结果： 腹膜后去分化脂肪肉瘤的影像学表现为体积较大的不均质肿块，多数呈分叶状(30.8%，4/13)或多结节状(46.2%，6/13)，侵犯邻近组织器官(46.2%，6/13)；病灶内部包含不同比例的脂肪成分和非脂肪成分，多数情况下其分界清楚。去分化成分CT表现为软组织密度或混合密度等，其中磨玻璃密度灶提示可能存在黏液性成分，部分可见钙化或骨化(45.5%，5/11)，CT和MR增强扫描去分化成分多表现为不均匀明显强化(84.6%，11/13)，中央伴囊变、坏死(61.5%，8/13)，病理上对应为多种类型软组织肉瘤，但无显著特异性。分化好的成分为脂肪为主肿块，其内伴纤维分隔或软组织结节，病理上对应为高分化脂肪肉瘤。淋巴结和远处转移少见。 结论： 腹膜后DDL的影像学表现多种多样，与不同分化成分比例和分布密切相关，其CT、MRI和增强扫描表现有一定的诊断价值。.
Keywords: Dedifferentiated liposarcoma; Magnetic resonance imaging; Retroperitoneal neoplasms; Tomography, X-ray Computed.