Retroperiton masses

Pathology of

Retroperitoneal Mass

The retroperitoneal space is a potential space extending posterior to the abdominopelvic cavity.

The tissue within this mixed potential and actual space is composed of:

Lymphatics and loose connective tissue.

Organs that are partially or completely

retroperitoneal include:

• Pancreas,

• kidney,

• Adrenal glands,

• Ureters.

Vascular structures:

• Aorta and inferior vena cava.

Significant lumbar nerves

traverse the space.

Differential diagnosis of retroperitoneal soft tissue mass

The term retroperitoneal tumour is at times confined to the lesions arising from tissues (muscles, fat, fibrous tissue, lymph nodes, nerves and developmental remnants) of this compartment but excluding origin from the retroperitoneal organs.

Malignant lesions: • Lymphoma (most common)

• Sarcoma (2nd most common)

• GIST

• Germ cell tumor

Desmoid tumors.

Benign lesions: • Lipoma

• Peripheral nerve sheath tumor

• Teratoma

• Paraganglioma

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

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.

Retroperitoneal sarcoma ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ


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%.


Macroscopically positive margin is one the

most important prognostic features in

determining local control and survival.

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.

The use of adjuvant and neoadjuvant

chemotherapy is not standard.


Patients with unresectable disease:

• May benefit from a course of preoperative radiotherapy or

chemotherapy in attempt to shrink the tumor.

• Palliative debulking surgery may be offered.

Patients with metastatic disease:

Solitary or limited metastases:

should be managed similarly to those with localized disease with

consideration for 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.)

GIST gastrointestinal stromal tumour

These tumors that derive from the precursors of the interstitial cells of Cajal may occur anywhere in the GI tract, but most often from the stomach and small intestine.

incidence is estimated to be approximately 1.5/100,000 per year.

Approximately 95% of GISTs are CD117 (c-KIT) positive.

GIST ـــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ

Surgery: • Remains the only potentially curative treatment for

patients with localized GIST.

• Optimal surgery requests complete excision of the

tumor without rupture in order to avoid seeding of

tumor cells.

• No role in advanced or metastatic disease.

Imatinib (targeted therapy):

• Tyrosine kinase inhibitor of c-KIT.

• Adjuvant: in tumors > 3 cm, for 1 year.

• Upfront therapy: in advanced and metastatic cases.

Desmoid tumors (aggressive fibromatosis)

Rare, benign neoplasms.

Arise from muscle fascia, aponeuroses, tendons, and scar tissue.

More commonly in females .

Associated with familial adenosis polyposis .

Tend to be locally aggressive and have a propensity 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.

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.

Health & Medicine

Retroperiton masses