Learning Objectives s11

CME Activity

Learning objectives: 1. Describe the imaging features of primary neoplastic and non-neoplastic retroperitoneal lesions. 2. Recognize specific imaging findings related to the different types of retroperitoneal tumors. 3. Discuss the differential diagnosis of primary retroperitoneal neoplasms.

Multiple-choice questions 1. Which of the following is true about primary retroperitoneal neoplasms? a- Primary retroperitoneal neoplasms are common tumors.

b- Metastasis is common in high-grade sarcomas.

c- Metastasis spread occurs through the lymphatic system.

d- Recurrence rates are low.

e- Retroperitoneal sarcomas are often very small at the time of diagnosis.

Neville A, Herts BR. CT characteristics of primary retroperitoneal neoplasms. Crit Rev Comput Tomogr 2004; 45(4):247–270.

2. What is the most frequent primary retroperitoneal tumor?

a- Liposarcoma

b- Leiomyosarcoma

c- Malignant fibrous histiocytoma

d- Rhabdomyosarcoma

e- Neuroblastoma

Rajiah P, Sinha R, Cuevas C, Dubinsky TJ, Bush WH, Kolokythas O. Imaging of Uncommon Retroperitoneal Masses. RadioGraphics 2011; 31:949–976.

3. Which of the following entities has the most FDG uptake? a. Well-differentiated liposarcoma

b. Dedifferentiated liposarcoma

c. Myxoid liposarcoma

d. Pleomorphic liposarcoma

e. Lipoma

Kitajima K, Kono A, Konishi J, Suenaga Y, Takahashi S, Sugimura K. 18F-FDG-PET/CT findings of retroperitoneal tumors: a pictorial essay. Jpn J Radiol 2013; 31:301–309.

4. Which of the following conditions manifests as a large retroperitoneal mass with necrosis and contiguous involvement of a vessel?

a- Liposarcoma

b- Leiomyosarcoma

c- Malignant fibrous histiocytoma

d- Rhabdomyosarcoma

e- Gastrointestinal stromal tumors

Rajiah P, Sinha R, Cuevas C, Dubinsky TJ, Bush WH, Kolokythas O. Imaging of Uncommon Retroperitoneal Masses. RadioGraphics 2011; 31:949–976.

5. Which of the following is true about retroperitoneal lipomas? a- Lipomas are rare in the retroperitoneum.

b- On images, lipomas can be confused with well differentiated liposacomas.

c- A fat-containing mass without enhancement or soft tissue component is seen on imaging.

d- Malignant change of lipoma to liposarcoma is virtually unknown

e- All the above. Craig WD, Fanburg-Smith JC, Henry LR, Guerrero R, Barton JH. From the Archives of the AFIP. Fat- containing Lesions of the Retroperitoneum: Radiologic-Pathologic Correlation. RadioGraphics 2009; 29:261–290.