Retroperitoneal Lymphadenopathy

Axial and coronal reformatted CT images show bulky retroperitoneal lymph nodes (arrows) and mesenteric lymph nodes (arrowheads). The lymph nodes are homogeneously enhanced and appear to surround the vessels.

Facts: Retroperitoneal Lymphadenopathy

• Diagnosed on CT or MRI by nodal enlargement that may be accompanied by displacement of adjacent structures
• Upper limit of normal at this location = 10 mm
• 8-10 "multiple" lymph nodes should be viewed with suspicion
• Large differential possibilities, including infection/inflammation and neoplasm.
• Generally, benign conditions do not exhibit massive conglomeration of lymph nodes

Differential Diagnosis:

• Infection: TB, MAI
• Inflammation: sarcoidosis, Castleman disease, bulky form of retroperitoneal fibrosis
• Neoplasm: lymphoma, metastasis
• Imaging features can significantly overlapped and it can be difficult to tell one way of the other. Biopsy is usually required for definitive diagnosis.

Potential Clues:

• Immunocompromised patients -- think of mycobacterial infection, lymphoma, Kaposi's sarcoma (esp. if there is cutaneous tumor), progressive generalized lymphadenopathy syndrome (lymphadenopathy in other locations)
• Multiple lymph node stations, homogeneous nodes, hepatosplenomegaly -- think of lymphoma
• Hyperenhancing -- think of hypervascular metastasis or Castleman disease

Our case: Retroperitoneal lymphadenopathy due to squamous cell carcinoma metastasis from head and neck cancer.

References:

1. Warshauer DM, Lee JKT, Patel H. Retroperitoneum. In: Lee JKT et al (eds), computed body tomography with MRI correlation, 4th edition, 2006.

2. Chapman S, Nakielny R. Aids to radiological differential diagnosis, 4th ed, 2003.