1. RETROPERITONEAL TUMORS
-Dr. Ashith Shetty

2. Anatomy
Retroperitoneal space lies between the posterior envelopment of the peritoneum and the posterior abdominal wall
Bounded
Anteriorly - posterior parietal peritoneum
Posteriorly-spine and back muscles
Superiorly- diaphragm
Inferiorly- levator ani muscles

4. Embryonic mesoderm predominates in the developing retroperitoneal space
The anterior border is quite convoluted, extending into the spaces between the mesentries of the small and large intestine.
Because of the rigidity of the superior, posterior, inferior boundaries, and the compliance of anterior margin, the retroperitoneal tumors tend to expand anteriorly towards peritoneal cavity

5. Incidence Retroperitoneal sarcomas are rare
Representing only about 0.1 to 0.2% of all malignancies in adults
Soft tissue sarcomas represent 7% of the cancers in children
15% of all soft tissue sarcomas

6. Etiology
Radiation
Chemical exposure like herbicides, thorium oxide, vinyl chloride
Familial- von Recklinghausen’s disease , Li- Fraumeni syndrome, Gardner syndrome
Genetic- mutations of p53 and RB1 genes

7. Presentation
Both benign and malignant tumors can arise from different tissues
Adipose- lipoma, liposarcoma
Smooth muscle- leiomyoma, leiomyosarcoma
Connective tissue- fibroma, fibrosarcoma
Striated muscle-rhabdomyoma, rhabdomyosarcoma
Lymph vessels- lymphangioma, lymphangiosarcoma

8. The most common primary malignancy is sarcoma Histological types
Liposarcoma
Leiomyosarcoma
Fibrosarcoma
Rhabdomyosarcoma
Neurofibrosarcoma
Malignant fibrous histiocytoma
Spindle cell carcinoma
Hemangiopericytoma
Synovial sarcoma

9. The most common sarcoma- liposarcoma 40%, leiomyosarcoma 25%
Malignant fibrous histiocytoma is being diagnosed with increased frequency
Rhabdomyosarcoma is the most common soft tissue sarcoma in children
In addition to sarcomas, other malignant lesions such as primary or metastatic carcinoma, lymphomas must be considered

10. Specific sarcomas tend to appear in certain age group:
Rhabdomyosarcoma in children
Synovial sarcoma in young adults
Liposarcoma and malignant fibrous histiocytoma in mid to late adult life

11. Malignancies in the retroperitoneum may result from the following:
Extracapsular growth of a primary neoplasm of retroperitoneal organs such as kidney, adrenal, colon, pancreas
Development of primary malignancy of retroperitoneal lymphatic system. Ex- lymphoma
Metastasis from primary malignancy into retroperitoneal lymph node. Ex- Ca. testis
Development of malignancy of soft tissue of retroperitoneum. Ex- sarcomas

13. Liposarcoma Most common sarcoma of adulthood
Appear in 4th -6th decade of life
Notorious for developing into large tumors
Morphology- histologically divided into
Well differentiated
Myxoid
Round cell
Pleomorphic variant

14. The well differentiated variant is relatively indolent
Myxoid type is intermediate in malignant behaviour
Round cell and pleomorphic variant are aggressive and frequently metastasize
All types of liposarcomas recur locally, unless adequately excised

15. Liposarcoma

16. Leiomyosarcoma Account for 25% of the retroperitoneal sarcomas
Occur in adults
Affects women more frequently than men
Present as painless firm masses
Maybe large and bulky and case abdominal symptoms

17. Histologically characterised by malignant spindle cells that have cigar shaped nuclei
Morphological variant
Prominent myxoid stroma
Epitheloid cells
Immunohistochemically they stain with antibodies to actin, desmin

18. Leiomyosarcoma

19. Malignant fibrous histiocytoma
It is being with diagnosed with increased frequency probably because of better understanding of the histopathology of the tumor
Characterised by considerable cytologic pleomorphism, bizarre multinucleate cells and storiform architecture

20. Morphology – these tumors are usually large (5-20 cm), gray- white unencapsulated masses but often appear circumscribed
Categorised into-
Storiform – pleomorphic
Myxoid
Inflammatory
Giant cell
Angiomatoid

21. Malignant fibrous histiocytoma

22. Clinical presentation
Mean age of presentation- above 50yrs
Slight male predominance (1.4: 1)
Most patients present with asymptomatic abdominal mass
Usually large in size
Not moving with respiration
Non mobile
Does not fall forward
Resonant on percussion

24. Abdominal pain present in half of the patients
Less common symptoms include
GI haemorrhage
early satiety
nausea
vomiting
weight loss
Back pain

25. Symptoms related to nerve compression by tumor (lumbar and pelvic nerves), lower extremity paraesthesia and paresis
Evidence of vena caval compression with lower limb oedema, varicocele, ascites and dilated abdominal wall veins

26. TNM Staging Primary tumor (T) T1: tumor less than or equal to 5cm
T2: tumor >5cm
a- superficial tumor
b- deep tumor
Regional lymph node(N)
N0: no regional node metastasis
N1: regional lymph node metastasis

27. Distant metastasis (M)
M0: no distant metastasis
M1: distant metastasis

28. Diagnostic evaluation
Accurate history
Complete physical examination with attention to all nodal areas and testicular examination in men
CT scan of the abdomen and pelvis with contrast enhancement
MRI
Angiography

29. Venography
CT guided core needle biopsy
Chest X-ray/ CT chest
LDH level
Beta hCG/ AFP level

30. Treatment Surgery is the main modality of treatment
Complete surgical resection is most effective
en bloc resection of the involved organs most commonly kidney, tail of pancreas, colon, small bowel

31. Vascular resection is considered when major blood vessels are involved
Palliative surgical procedures like debulking maybe considered
The mortality rate should be less than 5%

32. Radiotherapy – external beam radiation therapy, combined external beam irradiation and intraoperative brachytherapy used for local control of these malignancies.
Multiple drug chemotherapy including Adriamycin is found to be beneficial.
Chemotherapy applied to patients with locally advanced, high grade tumors

33. Prognosis Several features of sarcomas influence the prognosis:
Accurate histological classification
Grade of soft tissue sarcoma (G1 – G3) based on the degree of differentiation, average number of mitosis/hpf, cellularity, pleomorphism, extent of necrosis

34. Staging helps determine the prognosis and chance of successful excision of the tumor
Tumors arising in superficial locations have better prognosis than deep seated lesions

35. Summary Retroperitoneal tumors rare Most common are sarcomas
Usually presents as large abdominal or pelvic mass
Abdominal CT scan is most useful in evaluation
Abdominal approach is advised to allow en bloc resection

36. Total surgical resection is the mainstay treatment
Prognostic factor depends on size of tumor and histological grade
Local recurrence seen in 2/3rd of the patients
5-yr survival rate %

37. References
Schwartz textbook of surgery, 9th edition
Sabiston surgery, 18th edition vol. 2
Oxford textbook of surgery, 2nd edition vol.2
Essential surgical practice, Cushieri, Steele, Moosa, 4th edition
Bailey and Love, 24th edition
Robbins and Cotran, pathologic basis of disease, 7th edition

38. Thank you