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  • • Mesenchymal-derived soft-tissue neoplasms

    • Metastasize via the hematogenous route with the majority of metastases to the liver or lung

    • Behavior tends to be dictated by tumor grade rather than cell type of origin

    • Rarely cause symptoms until they grow to a large size

    • Vague abdominal symptoms are the most common presenting complaint


  • • Account for 15% of all sarcomas and 55% of all retroperitoneal tumors

    • Most common variant is a liposarcoma

Symptoms and Signs

  • • Nonspecific vague abdominal symptoms most common complaint

    • Abdominal discomfort

    • Early satiety

    • Nausea and vomiting

    • Weight loss

    • Palpable abdominal mass

Laboratory Findings

  • • A small percentage of patients present with hypoglycemia simulating an insulinoma

Imaging Findings

  • Chest film or thoracic CT scan: May demonstrate pulmonary metastases

    Abdominal CT scan or MRI

    • -Demonstrates the soft-tissue neoplasm and its relationship to adjacent retroperitoneal structures

      -MRI is typically more accurate than CT scan in defining the extent of tumor and invasion of surrounding structures

  • • Retroperitoneal sarcoma

    • Retroperitoneal teratoma

    • Retroperitoneal cyst

    • Retroperitoneal abscess

    • Retroperitoneal hematoma

    • Mesenteric cyst

    • Mesenteric lipodystrophy

    • Pseudomyxoma peritonei

    • Malignant peritoneal mesothelioma

    • Adrenal mass

    • Renal cell carcinoma

    • Intra-abdominal process with retroperitoneal extension

Rule Out

  • • Retroperitoneal abscess

    • Retroperitoneal hematoma

    • Adrenal mass

    • Renal cell carcinoma

    • Intra-abdominal process with retroperitoneal extension

  • • Thorough history and physical exam

    • Abdominal pelvic CT scan or MRI (preferred) to evaluate extent of lesion

    • Chest film or thoracic CT scan to evaluate for metastatic disease

    • Image-guided core needle biopsy vs open/laparoscopic incisional biopsy to establish diagnosis

When to Admit

  • • Work-up of these lesions can usually be performed as an outpatient

    • Admission for bowel obstruction or other tumor-related complications

When to Refer

  • • Multidisciplinary management of retroperitoneal tumors essential to ensure accurate diagnosis and appropriate treatment:

    • -Surgeon

      -Medical oncologist

      -Radiation oncologist



  • • Neoadjuvant chemoradiation


  • • Complete surgical extirpation with in-bloc resection of involved structures


  • • Operative excision in all patients without evidence of metastases and where all gross tumor can be removed (approximately 50% of cases)

    • Resection of pulmonary metastases should be considered in patients who have achieved local control and who have less than 4 pulmonary lesions


  • • Widespread metastatic disease

    • Inability to resect all grossly evident tumor

    • Tumor involvement of adjacent retroperitoneal structures is not a contraindication as long as they can be resected in continuity with the primary lesion

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