Retroperitoneal Sarcomas - A pictorial review Poster No.: C-1409 Congress: ECR 2013 Type: Educational Exhibit Authors: D. Douraghi-Zadeh, K. L. Shahabuddin, R. H. Thomas, E. Moskovic; London/UK Keywords: DOI: Cancer, Diagnostic procedure, CT, Abdomen 10.1594/ecr2013/C-1409 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. www.myesr.org Page 1 of 12
Learning objectives A pictorial guide to various types of retroperitoneal sarcomas (RPS) highlighting important imaging features which can help the radiologist to differentiate histological subtypes. To identify key patterns of disease behaviour of some of the more common RPS. To demonstrate the radiologist's role in diagnosis, assessing resectibility and staging. Background Various pathologies may arise in the retroperitoneum including primary and secondary neoplasms. Primary retroperitoneal tumours (benign and malignant) are rare. These are tumours that originate within the retroperitoneum but separate to the retroperitoneal organs. Retroperitoneal sarcomas (RPS) are very uncommon, malignant tumours of mesenchymal origin that are responsible for approximately one third of retroperitoneal neoplasms. The radiologist can play a pivotal role in management by aiding diagnosis and assessing tumour resectibility. Key information includes the location of the tumour, its size and the adjacent structures (relationship to the nearby organs and neurovasculature). RPS generally have a wide range of appearances on imaging and often can be nonspecific. However the presence (or absence) of certain characteristics - fat content, tumour enhancement/vascularity, calcification and pattern of disease spread can help to either differentiate or negate certain histological subtypes. The imaging investigation of choice in RPS is contrast enhanced CT - which can aid in diagnosis, staging, management and treatment response. MRI has poorer spatial resolution but is useful in assessing relationship to vital structures and in particular vasculature. PET-CT is useful for staging. A retroperitoneal location can be difficult to distinguish from an intra- peritoneal location. Key distinguishing features are mass effect causing displacement of retroperitoneal structures (such as pancreas, adrenal glands and kidneys). Page 2 of 12
Liposarcomas are the most common type of RPS - accounting for 70%. Less common histologic subtypes include leiomyosarcomas (15%), malignant fibrous histiocytomas (MFH). Rarer pathologies include solitary fibrous tumour and Ewings sarcoma. Imaging findings OR Procedure details Liposarcomas Liposarcomas (LPS) are usually well-differentiated containing abnormal fat but with dedifferentiated components which appear more solid. Other types such as myxoid, pleomorphic and mixed type also occur but are less common. Well Differentiated Liposarcomas (WDL) - have imaging characteristics similar to fat. They tend to have nodular septations internal vascularity and a heterogenous texture. Page 3 of 12
Fig. 1: Well Differentiated Liposarcoma (WDL)- Large retroperitoneal mass predominantly of fatty attenutation with irregular nodular septations References: Radiology Department, The Royal Marsden Hospital - London/UK De-differentiated Liposarcomas (DDL) - usually have well defined solid components that are distinguishable from the fatty tissue. Page 4 of 12
Fig. 2: Large De-differentiated Liposarcoma (DDL)- Note the septated, nodular fat density mass with a heterogenous enhancing soft tissue component. References: Department of Radiology, Royal Marsden Hospital, London/UK Leiomyosarcoma Leiomyosarcoma's are the second most common primary RPS. It is an uncommon malignant neoplasm of smooth muscle origin with a slight female predilection. Imaging appearances are non-specific meaning that correct diagnosis requires immunohistochemistry. Due to their indolent nature they can present late and of a significant size with the tumour undergoing necrotic or cystic changes centrally. Calcification is a rare feature. Occasionally venous extension into the IVC or retroperitoneal veins is noted. These tumours demonstrate contrast enhancement peripherally if large. Page 5 of 12
Due to its superior soft tissue contrast resolution and multiplanar modality, MRI also provides added value in retroperitoneal leiomyosarcomas [1,2]. It is useful in delineating the tumour's site of origin, its margins and invasion of adjacent structures. The signal intensity of the tumour is non-specific and variable depending on the degree of haemorrhagic and cystic changes, but its imaging characteristics are as follows [2]: T1 - isointense to muscle T2 spin-echo - intermediate to hypointense to fat T2 spin-echo fat saturation - predominantly hyperintense Fig. 3: Leiomyosarcoma - Large enhancing soft tissue mass coming off the IVC and also invading into its medial wall. There is associated mass effect with displacement of adjacent structures. References: Department of Radiology, Royal Marsden Hospital, London/UK Malignant Fibrous Histiocytoma (MFH) Page 6 of 12
These generally appear as well circumscribed soft tissue density masses with some areas of lower attenuation. They can range from hypervascular to hypovascular masses. They have a tendency to arise from, or be in close proximity to, the kidneys and /or adrenal glands which may help in offering a differential with RPS [3]. Fig. 4: Malignant Fibrous Histiocytoma (MFH) - Soft tissue mass that appears to arise from the left kidney but closer inspection reveals a cleft fat plane between the left kidney and retroperitoneal mass lesion. References: Department of Radiology, Royal Marsden Hospital, London/UK Solitary Fibrous Tumour (SFT) Page 7 of 12
These are a rare group of spindle cell neoplasms that include fibrous to cellular solitary fibrous tumours (SFT)s and related lesions such as lipomatous haemangiopericytoma and giant cell angiofibroma. They are most commonly located within the thorax although extra-thoracic locations include the retroperitoneum, deep soft tissues of the proximal extremities, abdominal cavity and head and neck. SFT's tend to have a discrete lobulated contour, are well defined and usually cause displacement of adjacent structures as opposed to invasion of adjacent structures. Furthermore they are hypervascular demonstrating avid enhancement post contrast administration and often have large perilesion collateral feeding vessels [4]. Fig. 5: Solitary Fibrous Tumour (SFT) - Lobulated mass, with a well defined contour causing displacement of adjacent structures and demonstrating avid enhancement post contrast administration. References: Department of Radiology, Royal Marsden Hospital, London/UK Chondrosarcoma Page 8 of 12
Extraskeletal chondrosarcomas are far less frequent than intraosseus chondrosarcomas and represent 2% of all soft tissue sarcomas. Histological subtypes of extraskeletal chondrosarcoma include myxoid (most common type), mesenchymal and welldifferentiated. Classically they present as lobulated soft tissue masses with calcific foci. Extensive calcification is more typical of extraskeletal mesenchymal chondrosarcoma than its skeletal counterpart, whereas the myxoid variant has more amourphous and punctuate calcification. Fig. 6: Chondrosarcoma - Large lobulated soft tissue mass with calcific foci References: Department of Radiology, Royal Marsden Hospital, London/UK Ewing's Sarcoma Page 9 of 12
Although commonly regarded as an osseous sarcoma in paediatric patients, approximately 20% of Ewing's sarcoma family of tumours (ESFT) are seen in adults and are extra-skeletal in location. ESFT represent a group of high-grade small round cell tumors, including Ewing sarcoma of bone, extra skeletal Ewing sarcoma, peripheral primitive neuroectodermal tumor (PNET), and Askin tumor (thoracopulmonary PNET). These tumours can arise from solid organs and usually do not cross the midline. ESFT has a propensity for the kidney and retroperitoneum and can invade adjacent organs or structures such as the vasculature (renal vein, or inferior vena cava) similar to renal cell carcinoma [5]. In the retroperitoneum it can also invade the paraspinal regions with neuroforaminal and spinal invasion best assessed on MRI. Page 10 of 12
Fig. 7: Ewing Sarcoma Family of Tumours (ESFT) - Large retroperitoneal soft tissue mass originating from the kidney, not crossing the midline but demonstrating invasion of the adjacent vasculature. (NB the presence of liver metastases also). References: Department of Radiology, Royal Marsden Hospital, London/UK Conclusion RPS consist of a variety of sarcoma subtypes, with liposarcomas the most common. This pictorial review helps illustrate some pertinent imaging features that can help characterise the particular sarcoma, although tissue typing with a percutaneous biopsy remains the gold standard. In addition to this, imaging can provide the surgical team with valuable information with regards to tumour resectability and staging. References 1. Hartman et al. Leiomyosarcoma of the retroperitoneum and inferior vena cava: radiologic-pathologic correlation. Radiographics 1992; 12(6):1203-1220. PMID: 1439022 2. O'sullivan et al. Radiological imaging features of non-uterine leiomyosarcoma. Br J Radiol 2008; 81(961):73-81 3. Goldman et al. The varied radiographic manifestations of retroperitoneal malignant fibrous histiocytoma revealed through 27 cases. J Urol 1986 Jan; 135 (1): 33-8 4. Wignall et al. Solitary Fibrous Tumours of the Soft Tissues: Review of the Imaging and Clinical Features with Histopathologic correlation. AJR 2010; 195:W55-W62. 5. Nishino et al. Primary retroperitoneal neoplasms: CT and MRI findings with anatomic and pathologic diagnostic clues. Radiographics 2003; 23:45-57. Personal Information Dr Dariush Douraghi-Zadeh MBBS FRCR Radiology SpR Department of Radiology Royal Marsden Hospital, London, UK Page 11 of 12
email: dariushdouraghi@gmail.com Dr Khawaja Shahabuddin MRCP FRCR Radiology Fellow Department of Radiology Royal Marsden Hospital, London, UK email: khawaja@doctors.org.uk Dr Robert Thomas MRCP FRCR Radiology Fellow Department of Radiology Royal Marsden Hospital, London, UK Dr Eleanor Moskovic FRCP FRCR Consultant Radiologist Department of Radiology Royal Marsden Hospital, London, UK Page 12 of 12