What causes retroperitoneal lymphadenopathy?

Causes of Retroperitoneal Lymphadenopathy

Retroperitoneal lymphadenopathy has multiple etiologies including malignancies, infections, inflammatory disorders, and rarely, mechanical causes such as prosthetic joint wear debris. The most appropriate diagnostic approach depends on patient risk factors, associated symptoms, and imaging characteristics.

Common Causes

Malignant Causes

• Lymphoma: Most common hematologic malignancy presenting with retroperitoneal lymphadenopathy
  • Diffuse large B-cell lymphoma is the most frequent subtype presenting primarily in the retroperitoneum 1
  • Other lymphoma subtypes include follicular lymphoma, small lymphocytic lymphoma, and Hodgkin lymphoma
• Metastatic cancer:
  • Testicular cancer commonly metastasizes to retroperitoneal lymph nodes 2
  • Renal cell carcinoma with retroperitoneal lymph node involvement indicates poorer prognosis 3, 4
  • Gynecologic malignancies
• Rosai-Dorfman-Destombes Disease (RDD):
  • Rare histiocytic disorder that can present with retroperitoneal lymphadenopathy 2
  • Typically presents with massive, painless bilateral cervical lymphadenopathy but can affect retroperitoneal nodes 5

Infectious Causes

• HIV and opportunistic infections:
  • HIV infection itself can cause lymphadenopathy
  • Opportunistic infections in immunocompromised patients 2
• Mycobacterial infections:
  • Tuberculosis (M. tuberculosis)
  • Nontuberculous mycobacterial infections
• Fungal infections:
  • Histoplasmosis
  • Cryptococcosis

Inflammatory/Autoimmune Causes

• IgG4-related disease:
  • Can mimic renal RDD 2
• Sarcoidosis:
  • Granulomatous disorder affecting multiple organ systems
• Castleman's disease:
  • Rare lymphoproliferative disorder that can present with retroperitoneal lymphadenopathy 6

Other Causes

• Retroperitoneal bleeding/hematoma:
  • Can mimic lymphadenopathy on imaging 2
• Prosthetic joint wear debris:
  • Rare cause of retroperitoneal lymphadenopathy from migration of prosthetic material 7

Diagnostic Approach

Initial Imaging

• CT abdomen and pelvis with contrast:
  • Gold standard for evaluating retroperitoneal lymphadenopathy
  • Helps assess size, number, and distribution of lymph nodes 2
  • IV and oral contrast aid in detection of retroperitoneal lymph nodes 2

Advanced Imaging

• PET/CT:

  • Useful for assessing metabolic activity of lymph nodes
  • Can help differentiate between benign and malignant causes
  • Not routinely recommended for initial staging of all conditions 2

• MRI abdomen and pelvis:

  • Alternative to CT with comparable efficacy for detection of retroperitoneal lymphadenopathy
  • Particularly useful when IV contrast is contraindicated 2
  • Diffusion-weighted imaging can improve lymph node identification 2

Tissue Diagnosis

• Needle biopsy with immunophenotyping:

  • More than half of hematologic malignancies can be diagnosed this way 1
  • Should include flow cytometry and immunohistochemistry

• Excisional biopsy:

  • May be necessary for definitive diagnosis when needle biopsy is inconclusive
  • Preferred method for lymphoma diagnosis when feasible

Clinical Pearls and Pitfalls

Pearls

• Lymph nodes >2 cm in size are more concerning for malignancy 6
• In patients with metastatic renal cell carcinoma, the absence of retroperitoneal lymphadenopathy is associated with better survival 4
• Consider prosthetic joint wear debris in patients with joint replacements and otherwise unexplained retroperitoneal lymphadenopathy 7

Pitfalls

• Non-malignant causes of lymphadenopathy are more common in patients with higher HIV viral loads and lower CD4+ T-cell counts 2
• Imaging findings in immunocompromised patients may be due to opportunistic infections rather than cancer recurrence or spread 2
• Renal involvement in RDD has a poor prognosis with a 40% mortality rate 2

Special Considerations

• In patients with HIV, always consider both malignant and non-malignant causes of lymphadenopathy 2
• Patients with renal cell carcinoma and retroperitoneal lymphadenopathy have worse response to immunotherapy and poorer survival compared to those without lymphadenopathy 3
• In testicular cancer, the presence and extent of retroperitoneal lymphadenopathy significantly impacts staging and treatment decisions 2