Symposium on Case Study

Symposium on Case Study,Department of Radiology, the second affiliated hospital of Sun yat-sen universityDuan Xiao-hui,Clinical features,Presentation： 36-year-old male with a lumbago for 1 months and have a history of NPC for about 5 years.PE：percussion pain of the low back.,T2WI,Balance-FFE,Coronal Balance-FFE,T1WI,T1WI-IP,T1WI+C,Coronal T1WI+C,MRA,43 s,1.05 m,21 s,?,Biopsy Pathology: seminoma with syneytiotrophoblast（精原细胞合并合体滋养细胞）,T1WI+C ,1 month after chemotherapy,seminoma,Primary extragonadal（性腺外的） seminoma of the retroperitoneum are rarely and without specific radiologic findings.,Diagnosis of these tumors is often challenging for radiologists,How to make an accurate radiologic diagnosis or narrow the differential diagnosis ?,1. Determining tumor locationcharacterizing the retroperitoneal spaceidentifying the organ of origin2. Recognizing specific features of various retroperitoneal tumors evaluating patterns of spreadtumor componentsvascularityspecific signs,First step-whether the tumor is located within the retroperitoneal space?,The displacement of normal anatomic structuresAnterior displacement of retroperitoneal organs (eg, kidneys, adrenal glands, ureters, ascending and descending colon,pancreas, portions of the duodenum) .Displacement of major vessels and some of their branches.,Second step-whether the tumor originates from a retroperitoneal organ？,Identification of the organ of originbeak sign鸟嘴征 phantom (invisible) organ sign器官无形征embedded organ sign器官包埋征 prominent feeding artery sign重要供血动脉征,1. beak sign鸟嘴征,when a mass deforms the edge of an adjacent organ into a “beak” shape, it is likely that the mass arises from that organ (beak sign),-,+,mucinous cystadenocarcinoma of the pancreas,2.phantom (invisible) organ sign 器官无形征,Large mass arises from a small organ, the organ sometimes becomes undetectable. （ phantom organ sign）. Howeer, false-positive - huge retroperitoneal sarcomas that involve other small organs such as the adrenal gland.,3.embedded organ sign器官包埋征,part of an organ appears to be embedded in the tumor .,gastrointestinalstromal tumor（GIST） of the duodenum,4.prominent feeding artery sign重要供血动脉征,Hyperascular masses are often supplied by feeding arteries.A finding that provides an important key to understanding the origin of the mass .,Third Step ：Imaging features that may narrow the differential diagnosis,Recognizing specific features of variousretroperitoneal tumors patterns of spreadtumor components vascularityspecific signs,1. patterns of spread,Extend between normal structures: Lymphangiomas(淋巴管瘤） and ganglioneuromas（神经节瘤）Extend along normal structures: Tumors of the sympathetic ganglia（交感神经节( paragangliomas（副神经节瘤）, ganglioneuromas（神经节瘤）Surround adjacent vessels（CT angiogram sign” or “floating aorta sign”）：Lymphoma,2.Characteristic tumor components,fat -脂肪myxoid stroma-粘液基质calcification-钙化 collagen fibers-胶原纤维necrosis portion -坏死cystic portion-囊变 small round cells-小圆细胞,tumor components- Fat,tumor components- Fat,Lipoma: homogeneous and well defined and consists almost entirely of fat.Liposarcoma: somewhat irregular and illdefined.Teratomas:fluid attenuation or signal intensity, fat-fluid levels, and calcifications.,tumor components-Myxoid Stroma （粘液基质）,Myxoid stroma appears hyperintense on T2WI and shows delayed enhancement. Including ：neurogenic tumors (schwannomas, neurofibromas, ganglioneuromas, ganglioneuroblastomas, malignant peripheral nerve sheath tumors), myxoid liposarcomas. （粘液型脂肪肉瘤）myxoid MFH（粘液型恶纤祖）,tumor components- Calcification,tumor components- Collagen Fibers,Typically have low SI on T1- and T2WI. With a delayed enhancement.,tumor components- Necrosis Portion,Usually seen in tumors of high-grade malignancy such as leiomyosarcomas.Leiomyosarcomas(平滑肌肉瘤） tend to develop massive cystic degeneration. They have central necrosis more commonly than other sarcomas.,tumor components- Cystic Portion,Some tumors are completely cystic in appearance， include lymphangiomas (淋巴管瘤） and mucinous cystic tumors（粘液蛋白囊肿）.Solid tumors with a partially cystic portion include neurogenic tumors.,tumor components- Small Round Cells,On T2WI, homogeneous masses with relatively hypointense areas representing densely packed cellular components .Lymphomas : homogeneous, with minimal contrast enhancement at CT and relatively low signal intensity at T2WI. An exception is PNET- often appears heterogeneous on MRI.,3.Vascularity,Extremely hypervascular tumors : paragangliomas and hemangiopericytomasModerately hypervascular tumors : myxoid MFH, leiomyosarcomas, and many other sarcomas. Hypovascular tumors : lowg-rade liposarcomas, lymphomas, and many other benign tumors.,Dynamic Enhancement Patterns,4.Specific Signs,Target sign-靶征Bowl of fruit sign-?Whorled appearance-漩涡征Flow void-血管留空征Speckled enhancement-斑点状强化Associated lymphadenopathy-伴随的淋巴结肿大,Target sign-靶征,Central area of low to intermediate SI surrounded by a ring of high SI on T2WIAt histopathologic，fibrous tissue centrally and myxoid tissue peripherally Commonly seen in neurofibroma and schwannoma,Neurofibroma,Bowl of Fruit Sign-?,A mosaic of mixed low,intermediate, and high SI on T2WI as a result of admixture of solid components, cystic degeneration, emorrhage, myxoid stroma, and fibrous tissue . Commonly seen in malignant fibrous histiocytoma, synovial sarcoma, and Ewing sarcoma.,Myxoid MFH,Whorled Appearance-漩涡征,consists of linear or curvilinear structures of low SI on T2WI. At histopathologic,it corresponds to bundles of Schwann cells and collagen monly seen in ganglioneuroma（神经节瘤） and neurofibroma（神经纤维瘤）,ganglioneuroma,Flow Void-血管留空征,A flow void is commonly seen in hemangiopericytoma(血管外皮细胞瘤）, AVM, and alveolar soft-part sarcoma（泡状软组织肉瘤）,hemangiopericytoma,Speckled Enhancement-斑点状强化,Corresponds to an intratumoral septum like structure at histopathologic analysis.Frequently seen in malignant lymphoma,leiomyosarcoma (平滑肌肉瘤), and rhabdomyosarcoma（横纹肌肉瘤）.,Leiomyosarcoma,Associated Lymphadenopathy伴随的淋巴结肿大,Malignant lymphoma 恶性淋巴瘤Neuroblastoma 神经母细胞瘤Malignant fibrous histiocyto