RETROPERITONEAL TUMORS -Dr. Ashith Shetty

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

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

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

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

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

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

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

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

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

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

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

Liposarcoma

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

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

Leiomyosarcoma

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

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

Malignant fibrous histiocytoma

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

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

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

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

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

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

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

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

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%

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

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

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

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

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- 36-58%

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

Thank you