CT or MRI can help classify retroperitoneal lesions, with CT-guided biopsy obtaining tissue for diagnosis. Retroperitoneal sarcoma is the second most common malignant tumor arising from extraskeletal tissues like fat or muscle. Common types are leiomyosarcoma, liposarcoma and fibrosarcoma. Primary treatment is attempting a gross total resection, though resectability ranges from 65-85% due to factors like vessel or spinal cord invasion. Even with complete resection, local recurrence and 5-year survival rates remain poor, though adjuvant radiation may help decrease local failure. For unresectable or metastatic disease, preoperative therapies and palliative options are considered.

2. Diagnostic work up
• Computed tomography (CT):
– Large lesions with fatty components causing mass effect
frequently represent liposarcomas.
– Teratomas often have fat, fluid, and calcified components.
– Paraspinal locations point to nerve sheath tumors or
neurogenic derivation .
• Magnetic resonance imaging (MRI) may demonstrate
additional imaging details to further classify the
lesion.
• CT-guided needle biopsy may be performed as the
initial means of obtaining tissue for histologic
diagnosis

3. RETROPERITONEAL SARCOMA
• Second most common malignant RPT.
• Arise from: nonepithelial, extraskeletal tissues:
(fat, muscle, nerve and nerve sheath, blood
vessels, other connective tissues).
• Incidence: 9,220 cases per year in the United
States.
• Common types:
– Leiomyosarcoma
– Liposarcoma
– Fibrosarcoma

5. • Primary treatment of retroperitoneal soft
tissue sarcoma (STS) is to attempt a gross total
resection.
• Criteria for unresectable tumors commonly
include major vessel invasion and spinal cord
or vertebral body involvement.
• Resectability has been reported in recent
series to range from 65% to 85%.

6. • Macroscopically positive margin is one the
most important prognostic features.
• Even after a complete excision of RPS, local
recurrence rates (33% to 77%) and overall
survival rates (35% to 63% 5-ys OS) are poor.
• retrospective data demonstrate a decrease in
local failure with adjuvant radiation therapy.

7. • Patients with unresectable disease:
– preoperative radiotherapy or chemotherapy in
attempt to shrink the tumor.
– Palliative debulking surgery may be offered.
• Patients with metastatic disease:
– Solitary or limited metastases:
• preoperative radiation therapy and/or chemotherapy,
metastasectomy, radiofrequency ablation. Chemotherapy
may be considered (most commonly, Doxorubicin-based
regimens).
– Disseminated metastatic disease:
• treated with palliative intent (chemotherapy, radiation
therapy, palliative surgery or best supportive care.)

8. Desmoid tumour
• Rare, benign neoplasms.
• Arise from muscle fascia, aponeuroses, tendons, and
scar tissue.
• More commonly in females .
• Associated with familial adenosis polyposis .
• locally aggressive and high chances to recur locally
after resection.
• Treatment is complete resection with a 2-3 cm margin.
• Postoperative radiation therapy is used in cases with an
unresectable primary, after multiple local recurrences.

9. Schwannomas
• Most common benign tumors in the retroperitoneum.
• Typically form large, well-circumscribed masses (may
display cystic degeneration, calcification, hemorrhage).
• MRI is the recommended imaging study.
• Not suggest CT-guided biopsy or fine-needle aspiration
for the diagnosis because of the risk of hemorrhage as
it is usually a highly vascular tumor.
• Complete surgical resection with negative margins is
the treatment of choice