Annals of Vascular Surgery
Volume 24, Issue 4 , Pages 551.e1-551.e4, May 2010

Laparoscopic Resection of Retroperitoneal Schwannoma Near the Inferior Vena

Clinic of General Surgery, Tepecik Training and Research Hospital, Izmir, Turkey

published online 08 February 2010.

Article Outline

Background

Schwannomas are usually benign tumors that arise from the schwann cells in the neural sheaths of peripheral nerves. Most schwannomas occur in the head, neck, or limbs and rarely in the retroperitoneal space. In the retroperitoneal space, schwannomas are most commonly located near the adrenal gland. We report a successfully resected retroperitoneal benign schwannoma near the inferior vena cava (IVC) using laparoscopic surgery.

Methods/Results

A 33-year-old woman presented with dull abdominal pain for several months. Magnetic resonance imaging confirmed the existence of a round, sharply demarcated retroperitoneal solid tumor, 42 × 52 mm in size, located between the anterior of the right kidney and the IVC, which was compressed but still patent. The lesion was laparoscopically resected, and pathologic examination revealed a degenerative schwannoma.

Conclusion

Laparoscopic surgery is very useful and feasible in the diagnosis and treatment of retroperitoneal schwannoma, with minimal invasiveness and early postoperative recovery.

 

Schwannomas are usually benign tumors that arise from the schwann cells in the neural sheaths of peripheral nerves.1, 2, 3, 4 Most schwannomas occur in the head, neck, or limbs and rarely in the retroperitoneal space.3, 4 In the retroperitoneal space, schwannomas are most commonly located near the adrenal gland.5 Schwannoma is known as neurilemoma or perineural fibroblastoma.4 The disease can occur at any age.2 Benign and malignant schwannomas are subclasses of soft-tissue neoplasms. The main locations are the cranial and peripheral nerves and the retroperitoneum. In the retroperitoneal space, benign schwannomas arise below the renal artery.6 The retroperitoneal form is very rare and generally asymptomatic, with an incidence of only 0.7-2.7%.1, 2, 3 The malignant form is much more uncommon.2 Diagnosis is very difficult preoperatively because both clinical and radiologic features are not specific to schwannoma.1, 7 Complete removal along with the capsule is the treatment of choice, and the recurrence rate is low.4

Since its introduction for cholecystectomy in 1987, the indications for laparoscopic surgery have expanded in abdominal diseases.1

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Case Report 

A 33-year-old female was referred to our institution with a right retroperitoneal mass thought to arise from the adrenal gland. The patient initially presented with vague abdominal pain. She was not on any medications. Her medical history was negative for other diseases or malignancy. On physical examination, her abdomen was soft and not tender, with no palpable mass. Laboratory tests were normal, including serum levels of electrolytes, aldosterone, cortisol, and urine catecholamines. Magnetic resonance imaging (MRI) of the region showed a hypointense lesion on T1-weighted images and hyperintense lesion on T2-weighted images. MRI confirmed the existence of a round, sharply demarcated retroperitoneal solid tumor, 42 × 52 mm in size, located between the anterior of the right kidney and the inferior vena cava (IVC), which was compressed but still patent. We performed laparoscopic surgery.

Surgical Technique 

Under general anesthesia, the patient was placed in the full left lateral decubitus position, both legs slightly flexed to avoid crural neuropathy, a cushion placed under left flank, and the table flexed to widen the space between the anterior iliac spine and inferior costal margin. We used four trocars for a transperitoneal approach, according to the body habitus; the first 12 mm optical trocar was inserted in the anterior axillary line, under the costal margin. A 30-degree laparoscope was introduced through this trocar. A second 12 mm trocar was introduced 5 cm away from the optical trocar and 2 cm in front of the anterior axillary line. Two other 10 mm trocars were introduced under the costal margin, 7 cm on either side of the optical trocar, as shown in Figure 1. Carbon dioxide was used for peritoneal insufflation, and abdominal pressure was maintained at 12-15 mm Hg. The patient was diagnosed as having a right adrenal mass. The right adrenal and right kidney were carefully visualized. The mass was situated anterior to the right kidney and IVC. The liver was retracted with an atraumatic liver retractor for good exposure. Mobilization of the liver allowed identification of the mass. The procedure started with an incision of the subhepatic peritoneum using a hook. The mass was detected in the retroperitoneal space between the anterior to the right kidney and the IVC (Fig. 2). After opening the peritoneal membrane over the tumor, a smooth mass 5 cm in size was visible (Fig. 3). The capsulated retroperitoneal mass was excised, using a bipolar Endoclip applier (Ligaclip; Ethicon, Somerville, NJ). We took out the resected tumor through the 12 mm trocar using a surgical bag (Endo catch, Ethicon). Hemostasis was checked. A closed suction drain was left in the surgical bed for 24 hr. The total operation time was 120 min, and blood loss was about 200 mL. The resected specimen measured 4 × 5 cm. The tumor was diagnosed as a benign schwannoma through histologic and immunohistologic examinations. The tumor showed a typical histologic configuration of benign schwannoma with immunohistochemical expression of a neurogenic marker (S-100 protein) but did not show a myogenic marker (smooth muscle actin) (Fig. 4, Fig. 5). The patient's postoperative course was uneventful, and he was discharged from our hospital on the fifth day postoperation. He has had no recurrences.

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Discussion 

Schwannoma is a neurogenic tumor arising from schwann cells in the peripheral nerves and is most commonly found in the head, neck, and limbs.1 According to Das Gupta et al.,8 benign schwannoma occurs mainly in the cephalocervical region (44.8%), limbs (32.6%), and rarely in the retroperitoneal space (0.7%).1 Retroperitoneal schwannomas (also termed “neurilemmomas” or “neurinomas”) are rare tumors that arise from the paravertebral region.6 In a review of 303 patients with schwannomas, only two (0.7%) were found in the retroperitoneum;8 and in another study, two (2.6%) cases were found out of a total of 76 schwannomas.9 In the retroperitoneal space, they occur most commonly between 20 and 50 years of age, being slightly more common in women.10 We present a 33-year-old female patient with a tumor located in the retroperitoneal space anterior to the right kidney and near the IVC.

Schwannomas usually have no special clinical symptoms.11, 12 The tumors frequently reach a large size and are discovered incidentally because of the flexibility of the retroperitoneum. Cystic degeneration, calcification, and hemorrhage may be seen.12 They are ususally painless, slow-growing masses with a tendency to arise from sensory or motor nerves, causing nonspecific pain and symptoms according to the affected nerve.13 The presenting symptoms depend on the type and location of the neuronal tissue involved and the size of the tumor. Most patients complain of nonspecific pain and/or paresthesias or motor impairment.14 Singh and Kapoor14 reported three atypical, very rare cases of schwannoma. One case presented with flank pain and hematuria, one presented with headache and secondary hypertension, and one presented with recurrent renal colicky pain. In our case the mass was found incidentally and the patient had a vague abdominal pain. She was referred to our hospital after being misdiagnosed with a malignant adrenal mass. Before surgery, we ruled out a malignant adrenal mass by laboratory tests.

There is no gold standard noninvasive diagnostic method for retroperitoneal schwannoma. Ultrasound, computed tomographic (CT) scanning, and MRI are nonspecific in most cases. Ultrasound is sensitive to calcification and cystic changes.15 Qiang et al.2 reported that CT scans typically show the tumor margins (smooth and sharp), liquefaction, necrosis, and hemorrhage in the tumor. Hayasaka et al.16 reported that MRI of benign schwannomas typically shows hypointensity on T1-weighted images and hyperintensity on T2-weighted images. These findings are characteristic of, but not specific to, schwannomas and have been reported in only 57% of cases. Additionally, other neurogenic tumors, such as ganglioneuroma, appear more commonly in the retroperitoneum than schwannomas and have similar findings on CT and MRI. Moreover, CT-guided fine needle aspiration biopsy does not seem to provide an accurate preoperative diagnosis, especially in patients with degenerative schwannoma.4 Definitive diagnosis is achieved by partial or complete mass resection. In our case MRI showed a 42 × 52 mm round, sharply demarcated retroperitoneal solid tumor on low–signal intensity T1-weighted images and high–signal intensity T2-weighted images. Moreover, CT-guided fine needle aspiration biopsy can be used but is usually unreliable in large tumors in which cellular pleomorphism is present in areas of degeneration. Many investigators do not recommend this modality as a diagnostic method.10, 17

Neurilemmomas are usually oval, solitary, firm, and smooth-surfaced tumors. Their diameter is usually <5 cm. Large neurilemmomas may exhibit cystic degeneration or hemorrhage and rarely calcifications.14 If a neurilemmoma originates from a large nerve trunk, it can be dissected from the rest of the nerve, whose axons are not involved by the tumor.4 Histologically, schwannomas consist of Antoni type A and type B tissues.14, 15 Benign variants are alternations of these Antoni A and B areas, with a diffuse positivity for S100 protein in the cytoplasm of the tumor cells.1, 2 Malignant degeneration of schwannomas is extremely rare and usually associated with von Recklinghausen disease.2

According to Qiang et al.,2 the ideal treatment of schwannoma is complete resection of the tumor and capsule without injuring the adherent organs such as the IVC, renal arteries, and veins. Some investigators believe that simple enucleation or partial excision is sufficient because of the benign nature of this tumor.18 However, complete surgical resection with negative margins is absolutely required for a malignant schwannoma.2 In our case, the patient underwent complete resection laparoscopically.

In the literature, six other cases of laparoscopic resection of retroperitoneal schwannoma have been reported.19, 20, 21 However, the large vessels were compressed in two cases;5, 14 in one case the tumor compressed the right common iliac vein and IVC,14 and in the other case the tumor compressed the IVC.5 In our case, the tumor compressed the IVC, but many precautions were required because of the location of the tumor. The main risk due to compression of the IVC was venous embolism and hemorrhage. Nevertheless, we performed an extensive dissection of the IVC with a conventional laparoscopic bipolar cauter and scissors. As a result, such an operation requires extensive experience both in laparoscopy and in vascular surgery.

In conclusion, retroperitoneal schwannomas are difficult to diagnose preoperatively. MRI, ultrasound, and CT-guided fine needle aspiration biopsy do not provide an accurate preoperative diagnosis, especially in case of degenerative schwannoma. The treatment of choice is complete excision of the schwannoma. However, the excision of retroperitoneal and larger tumors may be diffucult because of adjacent vital structures.The procedure can be performed safely using a laparoscopic approach. Laparoscopic surgery is very useful and feasible in the diagnosis and treatment of retroperitoneal schwannoma, with minimal invasiveness and early postoperative recovery.

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References 

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PII: S0890-5096(09)00327-6

doi:10.1016/j.avsg.2009.07.038

Annals of Vascular Surgery
Volume 24, Issue 4 , Pages 551.e1-551.e4, May 2010

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