Radiology Teaching Files > Case 52338070

Last visited 06-01-2011 RETROPERITONEAL MASS
Contributed by: Aaron Wickley, Resident, SAMMC, Texas, USA.
Patient: male
History: Middle-aged male; History withheld

Fig. 1

Fig. 2

Multiple rounded, mildy enhancing homogenous soft tissue masses located in the retroperitoneum and in the mesentery. The aorta, IVC, and renal arteries are encased and displaced anteriorly. The superior mesenteric artery is encased. The vessels maintain patency. Enlarged, rounded axillary lymph nodes are also present.

Diagnosis: Chronic Lymphocytic Leukemia (CLL); Pathology proven.

Retroperitoneal Mass:

Location is key to diagnosis when a retroperitoneal mass is encountered. If arising from a retroperitoneal organ, a claw(or beak)signmay be evident in the organ of origin. Other signs that help identify organ of origin are the "embedded organ" sign, or the"phantom" (invisible)organsign. If no organ is identified, the mass is considered primary retroperitoneal. Retroperitoneal masses are almost always malignant.

Clues to aid in diagnosis:


  • In a lymphatic distribution, often in multiple nodal chains
  • large, homogenous and mildly enhancing
  • Encases but does not invade vessels
  • Nodes tend to coalesce


  • Mimicks lymphoma
  • Less common

Retroperitoneal fibrosis:

  • Confined to retroperitoneum
  • Tends not to displace the Aorta anteriorly like lymphoma
  • May obliterate fat planes (with the psoas, etc.)
  • Less bulky than neoplastic lesions
  • Can cause urinary obstruction


  • Liposarcoma is the most common
  • Fat is usually a significant component in liposarcoma

Infectious/Inflammatory nodes (Atypical mycobacterium, TB)

  • Mimicks lymphoma
  • Nodes will usually remain discrete and will not coalesce
  • Nodes are often rim-enhancing
  • Intraperitoneal/mesenteric >> retroperitoneal

Metastatic disease:

  • Mimicks lymphoma
  • Colon, ovarian, breast, lung, carcinoid, melanoma
  • Degree of nodal involvement is much less pronounced



- Nishino et al. "Primary Retroperitoneal neoplasms: CT and MR imaging findongs with anatomic and pathologic diagnostic clues" Radiographics 2003 vol. 23 no. 1 45-57

- Sheth. et Al. "Mesenteric Neoplasms: CT Appearances of Primary and Secondary Tumors and Differential Diagnosis" Radiographics 2003 vol. 23 no. 2 457-473


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Additional Details:

Case Number: 52338070Last Updated: 06-01-2011
Anatomy: Other   Pathology: Other
Modality: CTAccess Level: Readable by all users

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