Role of Laparoscopy in Management of Retroperitoneal Masses

Abstract

The retroperitoneal space (in some respects a virtual space) is located between the posterior parietal peritoneum and the fascia that covers the muscles of the lumbar region. It extends upward to the diaphragm, downward to the base of the sacrum and iliac crests, and laterally to the external borders of the lumbar muscles and the ascending and descending colon. The retroperitoneum contains loose connective tissue surrounding lymph nodes, the aorta and inferior vena cava with their vascular branches, the adrenal glands, the kidneys and ureters, the pancreas, and portions of the duodenum.

The retroperitoneum can host a wide spectrum of pathologies, this includes, primitive retroperitoneal tumors (PRT) which are defined as masses that originate in the retroperitoneal space, independently of the organs present therein, and derive from tissues contained in the retroperitoneal space (adipose, muscular, vessel and nerve tissue), from embryonic remnants or heterotopies coming from one or more embryonic layers (ectoderm, mesoderm and endoderm) or from totipotent embryonic germs. Any growing lesions belonging to the retroperitoneal organs (kidneys, adrenal glands, excretory tract, pancreas and colon) or secondary invading them such as systemic masses (lymphomas) and metastases are not a part of this group.

According to the WHO classification, The PRTs are classified according to the tissue of origin into tumors arising from the connective tissue (fibrous, myofibroblastic and fibrohistiocytic tumors), those include fibroma, fibrosrcoma and malignant fibrohistiocytoma; from fat and they include lipoma and liposarcoma; from smooth muscle as leiomyoma and leiomyosarcoma; from skeletal muscles as rhabdomyosarcoma; from vascular origin as lymphangioma, lymphangiosarcoma, hemangioma, angiosarcoma and hemangiopericytoma; tumors from neurogenic origin include, neurofibroma, neurofibrosrcoma, shwannoma, ganglioneuroma, neuroblastoma and paragangliomas. And lastly, tumors of uncertain differentiation as peripheral primitive neuroectodermal tumor (PPNT), Ewing’s sarcoma and synovial sarcoma; and miscellaneous group which include castleman’s disease.

Late diagnosis of primary retroperitoneal tu¬mors is common because the retroperitoneum space is “adaptable” and the tumors remain asymptomatic for some time. The first, although late, symptom is usua¬lly the appearance of a visible and palpable mass. In other patients, the symptoms arise from compression or invasion of neighboring or¬gans and various types and sites of pain may be present in half the cases. Before a tumor can be described as primarily retroperitoneal, the possibility that the tumor originates from a retroperitoneal organ must be excluded. Many radiological signs have been described to assist in making a differential diagnosis, these include valid signs common to every imaging method used and other specific signs depending on the study technique.

In patients presenting with a retroperitoneal tumor, where the radiological appearance is uncertain or when the radiological appearance suggests a specific pathology where neoadjuvant treatment may be appropriate as induction therapy, a preoperative biopsy is mandatory. Additionally, if a tumor is deemed unresectable or the patient has distant metastases, a core needle biopsy may be indicated to confirm the diagnosis and to enable consideration of alternative therapy. In this respect, image-guided percutaneous biopsy can be used, but it suffers from a low diagnostic yield due to the small amount of tissue obtained and because an inflammatory infiltrate may have an appearance similar to a malignancy. Accordingly, surgical exploration with adequate tissue sampling is frequently necessary to establish a definitive diagnosis. Laparoscopic exploration potentially can provide a minimally invasive means to obtain adequate tissue for histologic diagnosis without the need for a major midline abdominal or flank incision.