Retroperitoneal tumors

1. Retro-peritoneal Tumors
By: ASM Minds Team
ASM Minds Team

2. ‫ده‬ ‫باللون‬ ‫الزيادات‬
‫الزيادات‬
‫معرفة‬ ‫هدفها‬ ‫بالنهاية‬ ‫اسئلة‬ ‫لوجود‬ ‫التركيز‬ ‫يرجى‬
‫تركيزك‬ ‫مدى‬

3. Retroperitoneum
• The retroperitoneum represents a complex potential space with
multiple vital structures

4. Retroperitoneum
• Boundaries
1- Anterior
2- Posterior
3- Medial
4- Lateral
5- Superior
6- Inferior

5. Anterior Boundaries
• Peritoneum
• ipsilateral colon
• Mesocolon
• Pancreas
• Liver
• stomach

6. RetroperitoneumDefinition
• Boundaries
1- Anterior
2- Posterior
3- Medial
4- Lateral
5- Superior
6- Inferior

7. Posterior Boundaries
• Psoas
• quadratus lumborum
• transverse abdominal
• iliacus muscles
depending on the tumor location and size, may be formed by the
• Diaphragm
• ipsilateral kidney
• Ureter
• gonadal vessels.

8. RetroperitoneumDefinition
• Boundaries
1- Anterior
2- Posterior
3- Medial
4- Lateral
5- Superior
6- Inferior

9. Medial Boundaries
• Spine
• paraspinous muscles
• The inferior vena cava (for right-sided tumors)
• The aorta (for left sided tumors).

10. Retroperitoneum
• Boundaries
1- Anterior
2- Posterior
3- Medial
4- Lateral
5- Superior
6- Inferior

11. Lateral Boundaries
• lateral abdominal musculature
depending on tumor location,
may include
• Kidney
• colon

12. Retroperitoneum
• Boundaries
1- Anterior
2- Posterior
3- Medial
4- Lateral
5- Superior
6- Inferior

13. Superior Boundaries
• Diaphragm
• right lobe of the liver
• Duodenum
• Pancreas
• spleen.

14. Retroperitoneum
• Boundaries
1- Anterior
2- Posterior
3- Medial
4- Lateral
5- Superior
6- Inferior

15. Inferior Boundaries
• iliopsoas muscle
• femoral nerve
• iliac vessels
• pelvic sidewall

16. Tumors of Retro-peritoneum
• The retroperitoneum can host a wide spectrum of pathologies,
including a variety of rare benign tumors and malignant neoplasms
that can be either primary or metastatic lesions.
• Malignant tumors of the retroperitoneum occur four times more
frequently than benign lesions. Sarcomas comprise a third of
retroperitoneal tumors.

17. Classification and Examples
• Cystic: teratoma, remnant of wollfian duct, dermoid, parasitic,
lymphogenous
• Solid Benign (20%): lipoma, leiomyoma, neurofibroma
• Malignant (80%): lymphoma, liposarcoma, fibrosarcoma,
neurofibrosarcoma

18. Teratoma

19. parasitic

20. lymphogenous

21. Remnant of wollfian duct

22. RETRO-PERITONEAL SARCOMA
Sarcomas constitute a heterogeneous group of rare solid tumors of
mesenchymal cell origin with distinct clinical and pathological features.
They are divided into two broad categories:
• Soft tissue sarcomas
• Bone sarcomas
Sarcomas collectively account for approximately 1% of all adult
malignancies and 15% of pediatric malignancies

24. Information about Sarcoma
• The true incidence of STS is underestimated, especially because a
large proportion of patients with gastrointestinal stromal tumors
(GISTs) may not have been included in tumor registry database before
2001.
• The most common subtypes of STS are undifferentiated pleomorphic
sarcoma, GISTs, liposarcoma, leiomyosarcoma, synovial sarcoma and
malignant peripheral nerve sheath tumors.

25. Information about Sarcoma
• The anatomic site of the primary disease represents an important
variable that influences treatment and outcome. Extremities (43%),
trunk (10%), visceral(19%), retroperitoneal (15%) and head and neck
(9%) are the most common primary sites.
• Approximately 80 percent of the neoplasms that arise within the
retroperitoneal space are malignant
• Furthermore, the majority of patients who present with a primary
retroperitoneal, extravisceral, unifocal soft tissue mass will be found
to have a sarcoma.
• Retroperitoneal sarcoma represents only a third of retroperitoneal
tumors

26. Information about Sarcoma
• . In adults, the most common histologic types of retroperitoneal STS
are liposarcomas (70%) and leiomyosarcomas (15%), followed by
pleomorphic undifferentiated sarcoma/malignant fibrous
histiocytoma
• A variety of other histologic types may be observed, but they are
much less common in the retroperitoneum than in other primary
sites.

27. Liposarcoma
(Most common)
(Like extremities well-differentiated liposarcomas in
everything except that in extremities it is well-
circumscribed and can be excised safely)
Types
1. Well differentiated liposarcoma
2. Dedifferentiated liposarcoma (lipomatous
component as type 1 but with a high-grade fibrous
element)
3. Pleomorphic liposarcoma (very poorly differentiated,
very high rate of recurrence, high sussiptibility for
distant metastasis to lung and liver, difficult to resect)

28. Soft tissue lesion
with a lipomatous
lesion
Leiomyoma of the
IVC

29. LEIOMYOSARCOMA
• Leiomyosarcoma (LMS) is sarcoma showing smooth muscle
differentiation; this is based on a combination of histomorphology
and immunophenotypic expression.
• In contrast to other sarcomas, the use of core‐needle biopsy
specimens in the primary diagnosis of LMS is increasingly recognized
to correlate poorly with final tumor grade in resection specimens and
this may have important implications in treatment (if we dx a patient
with leiomyosarcoma, we go directly for excision without core
needle biopsy)

30. OTHER TYPES OF SARCOMA
• Malignant peripheral nerve sheath tumors (sporadic or NF-1 ; poor
prognosis = larger size, NF-1, site and nerve involved)
• Synovial sarcoma (very aggressive, high rate of recurrence and
invasion)
• Solitary fibrous tumor (formerly known as a hemangiopericytoma)
(high rate of recurrence if not excised well with safety margin)
• Ewing and Ewing-like sarcoma (most common in young adult and
children)
• Desmoplastic small round cell tumor
• Undifferentiated/Unclassified sarcoma

31. Information about Sarcoma
• Among children, the most common histologic types of retroperitoneal
STS are extraskeletal: Ewing sarcoma/primitive neuroectodermal
tumors [PNET], alveolar rhabdomyosarcoma, and fibrosarcoma
• Approximately one-half of all retroperitoneal sarcomas are high-
grade tumors, although this varies according to histology.
• The majority of retroperitoneal liposarcomas are low- to
intermediate-grade lesions.
(low-grade = well-differentiated)

32. Information about Sarcoma
• STS most commonly metastasize to the lungs ; tumors arising in the
abdominal cavity more commonly metastasize to the liver and
peritoneum.
• Management of STS in adult patients is addressed from the
perspective of the following disease subtypes:
Retroperitoneal or intra-abdominal STS.
GISTs
Desmoid tumors
Rabdomyosarcoma

33. Genetic cancer syndromes with predisposition
to STS
Li-Faumeni syndrome (TP53 germline mutation)
• RMS
• Fibrosarcoma
• undifferentiated pleomorphic sarcoma.
(There may be breast, bone, stomach, pancreatic or prostatic
Breast, soft tissue and uterine body are the MC)

34. Genetic cancer syndromes with predisposition
to STS
Gardner syndrome
• desmoid tumors (and FAP, any patient with multiple desmoid, we
should do colonoscopy or CT colonogram to exclude FAP)
Carney-Stratakis syndrome
• gastric stromal sarcoma and paragangliomas
Carney’s triad
• gastric stromal sarcoma, paraganglioma and pulmonary chondroma

35. Diagnosis
• History: vague symptoms: abdominal discomfort, abdominal
distension, back pain, anorexia, fatigue & weight loss.
• Examination: abdominal mass: in most cases a mass could be
palpated. In some huge tumors, obstruction of IVC leads to
edematous legs, dilated abdominal veins and ascites or obstruction of
blood supply leading to LL ischemia

36. • Investigations:
1- CT with contrast abdomen and pelvis is the investigation of choice: To
assess site, relation to surrounding structure, pathological criteria esp. in
liposarcoma, resectability.
3- Biopsy
❖Pre-resection biopsy is not necessarily required ; consider biopsy if there is
suspicion of malignancy other than sarcoma. (as rhabdomyosarcoma,
lymphoma)
❖Image-guided (U/s or CT) core needle biopsy is preferred (not to take the
biopsy from a necrotic area, and not to injure surrounding vessels and
structures)
-Sometimes, if you diagnose a differentiated tumor with a biopsy, you may
miss an undifferentiated part
4- Patients with personal/family history suggestive of Li-Fraumeni syndrome
should be considered for further genetic assessment.

37. Leiomyoma

38. WORKUP
Prior to the initiation of therapy, all patients should be evaluated and
managed by multidisciplinary team.
• History and physical examination.
• Chest, abdomen and pelvis CT with contrast (metastasis)
• MRI may add some data (sarcoma extending to anterior abdominal
wall muscle to assess the magnitude of the problem)

39. Criteria for unresectability
• Radiographic findings that indicate
unresectability include
• Extensive vascular involvement (aorta, vena
cava and/or iliac vessels), although
involvement of the vena cava and iliac veins is
a relative rather than absolute
contraindication, as these vessels can often be
replaced with interposition grafts
• Peritoneal implants (end-stage)
• Distant metastases
• Involvement of the root of the mesentery
(specifically, the superior mesenteric vessels)
(necrotic intestine within few minutes)
• Spinal cord involvement (extension to spinal
foramina)

40. Staging
• Retroperitoneal sarcomas are staged using the same TNM system as
is used for extremity STS.
• However, the ability of the TNM staging system to discriminate
outcomes is limited.
• Several studies have found no prognostic role for tumor size in
retroperitoneal sarcoma.
• Given the importance of histologic grade and resection margins in the
prognosis of retroperitoneal STS, an alternative staging system has
been proposed that incorporates these features as well as the
presence or absence of metastatic disease. However, this staging
system is not in widespread use.

41. • Staging Tables

42. TREATMENT
• Surgical resection: has traditionally been the only potentially curative
treatment for a localized retroperitoneal STS (Gold Standard). However,
only 25% can be completely resected
• In unresectable cases: excision “debulking” combined with
radiochemotherapy is better than either alone.
• The ability to perform a complete surgical resection at the time of initial
presentation is the most important prognostic factor for survival.
• The primary oncologic goal is complete resection with microscopically
negative margins (R0 resection).
• However, the large size of most retroperitoneal tumors, coupled with the
inability to obtain wide margins due to anatomic constraints make this goal
difficult to achieve.
• In clinical practice, many resections are grossly complete but with
microscopically positive margins (R1 resection), so you have to go for
surgery again with re-resection, if not possible, give radiotherapy

43. TREATMENT
• Resection of adjacent organs such as the small bowel, colon or kidney
is often required to achieve a complete resection and bowel
preparation and evaluation of kidney function should be performed
prior to exploration.
• Liberal en-bloc resection of adjacent viscera may allow a subset of
patients to achieve wide, macroscopically negative surgical margins
who might otherwise have been considered unresectable.
• There is no survival benefit for incompleteresection (a "debulking"
procedure) in patients with unresectable retroperitoneal STS. (all or
non)

44. Adjunctive RT
• In contrast to extremity STS in which the most common site of first
recurrence is a distantsite, the primary pattern of treatment failure
after resection of a retroperitoneal STS is local.
• Adjunctive radiation therapy (RT) can be administered following
resection (adjuvant RT). However, increasingly, preoperativeRT is
being chosen for large high-grade or intermediate-grade STS.

45. Adjuvant RT
• It is often difficult to deliver postoperative radiation therapy because
the bowel and other organs fall into the resection cavity; however,
newer techniques such as
1- intensity-modulated RT (IMRT)
2- proton beam irradiation
make it more feasible but the therapeutic ratio is probably still more
favorable with preoperative RT. Nevertheless, it is reasonable to
consider the use of postoperative RT if it can be delivered safely

46. • In the postoperative setting, radiation doses to the tumor bed are
often limited by the large field size and the proximity and tolerance of
surrounding radiosensitive normal structures, such as the liver and
bowel.
• In fact, many multidisciplinary sarcoma groups do not routinely offer
postoperative RT to patients with resected retroperitoneal sarcomas
because of significant concerns about the narrow therapeutic ratio.

47. Preoperative RT
• The delivery of RT prior to surgery, with or without intraoperative RT
(IORT) at the time of resection, may permit the safe delivery of higher
RT doses than are possible in the postoperative setting
• There are several theoretical advantages for pre-operative as
compared to post operative RT for retroperitoneal STS
• The main advantage of preoperative RT is that the gross tumor
volume can be precisely defined for radiation treatment planning,
allowing accurate targeting of the radiation volume around the tumor.
• The tumor itself can displace small bowel-from high-dose radiation
field, resulting in safer and less toxic treatment.

48. • Higher radiotherapy doses can be delivered to the actual tumor field,
since bowel adhesion to tumor are less likely compared to the post-
operative setting
• The risk of intra-peritoneal tumor dissemination at the time of the
operation may be reduced by post-operative RT (if the tumor is fragile
and retroperitoneal malignancies are not encapsulated, opening the
tumor intra-operatively carries a higher risk for recurrence and
peritoneal sarcomatosis, so irradiation makes a fibrous capsule
around the tumor, decreases dissemination and turning an
unresectable tumor into a resectable one)

49. • Radiation is considered to be biologically more active in the pre-
operative setting.
• It is possible that an initially unresectable tumor can turn potentially
resectable for cure
These advantages may result in improvement in the therapeuticratio
when RT is administered preoperatively

50. Outcomes and prognostic factors
• Retroperitoneal sarcomas have a substantially less satisfactory
outcome than soft tissue sarcomas (STS) at other sites, such as the
extremities or trunk.
• Several factors contribute to poor outcome and a high rate of
recurrence (large size at diagnosis and unfavorable situation
anatomically)
• The surrounding normal tissues (liver, kidney, gastrointestinal tract,
spinal cord) have relatively low tolerance for radiation therapy (RT).
As a result, radiation dose levels must be kept below those typically
employed for extremity sarcomas.

51. • In contrast to extremity sarcomas, 90 percent of first recurrences are
local.
• Eventually, distant metastases develop in 20 to 30 percent . The main
sites of distant metastases are liver and lungs. Local recurrence rates
are higher with high-grade (poorly differentiated) tumors,
liposarcoma histology, and in patients with positive resection margins

52. Notes
• Which is more common retroperitoneal tumor, benign or malignant?
• Sarcomas
• Sarcomas are more common in adults or children?
• most common histologic types of retroperitoneal STS are
• most common in young adult and children:
• most common site of sarcoma is
• Better prognosis; retroperitoneal or STS elsewhere?
• if we dx a patient with leiomyosarcoma,

53. • Retroperitoneal tumors are mostly: high/low grade? Except?
• Most common site of retroperitoneal tumor metastasis is? If
abdominal cavity?
• If desmoid tumor = look for?
• Role of: TNM, Tumor size in prognosis?
• Invx of choice?
• When MRI in retroperitoneal tumors?
• Role of biopsy?

54. • Gold standard treatment?
• If unresectable? Debulking?
• which the most common site of first recurrence of extremity STS?
Retroperitoneal STS?
• PrePost operative radiotherapy?

55. Notes
• Which is more common retroperitoneal tumor, benign or malignant?
• Sarcomas 13
• Sarcomas are more common in adults or children? children
• most common histologic types of retroperitoneal STS are liposarcomas
• most common in young adult and children: Ewig and Ewig-like
• most common site of sarcoma is Extremities
• Better prognosis; retroperitoneal or STS elsewhere? Elsewhere
• if we dx a patient with leiomyosarcoma, we go directly for excision
without core needle biopsy

56. • Retroperitoneal tumors are mostly: high/low grade? Except? High-
grade except liposarcoma, low to intermediate-grade
• Most common site of retroperitoneal tumor metastasis is? If
abdominal cavity? Lung,, Liver&Peritoneum
• If desmoid tumor = look for? FAP; CT colonogram Colonoscopy
• Role of: TNM, Tumor size in prognosis? No role
• Invx of choice? CT abdomen and pelvis with contrast
• When MRI in retroperitoneal tumors? Extension to AAW
• Role of biopsy?

57. • Gold standard treatment? Surgical complete excision with safety
margins
• If unresectable? Debulking? Preoperativeradio, all or non-role
• which the most common site of first recurrence of extremity STS?
Retroperitoneal STS? distant site, local
• PrePost operative radiotherapy? Pre-operative