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Image of the Month—Diagnosis FREE

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Section Editor: Grace S. Rozycki, MD

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Arch Surg. 2006;141(9):942. doi:10.1001/archsurg.141.9.941-b.
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Operative resection was planned via laparoscopy, with an approach similar to that of a left adrenalectomy. Intraoperatively, a solid mass anterior and inferior to the left renal vein was identified; it appeared encapsulated and was easily dissected free from adjacent structures (Figure 2). Her postoperative course was uneventful and she was discharged home on hospital day 2. Pathologic examination demonstrated a 5.4 × 4.3 × 3.7-cm mass with a well-developed capsule. Tumor cells stained positive for S100 protein and CD34 cells and negative for desmin and muscle-specific actin, which is consistent with a benign schwannoma.

Place holder to copy figure label and caption
Figure 2.

A laparoscopic approach was used to dissect the inferior and lateral aspects of the well-encapsulated, solid mass well away from the renal blood vessels and ureter before rotating the entire mass out of the bed of dissection.

Graphic Jump Location

The majority of schwannomas occur in the head, neck, or extremities, with few cases reported originating in the retroperitoneum.1Because patients may be asymptomatic or only have vague abdominal pain, these schwannomas may be identified incidentally when evaluating other patient complaints or they may grow to large sizes prior to overt symptoms. Schwannomas are associated with von Recklinghausen disease in 5% to 18% of cases, and patients generally present between the ages of 20 and 50 years, with only 5% having onset in childhood or adolescence.2In the absence of von Recklinghausen disease, schwannomas rarely develop in the retroperitoneum, with only 3% of all sporadic schwannomas, both malignant and benign, occurring here.3When sporadic, they are typically benign lesions, particularly when identified in the retroperitoneum.

On gross appearance and diagnostic imaging, they are solitary, well-circumscribed masses that do not invade local tissues.4One can attempt to distinguish primary retroperitoneal benign tumors from their malignant counterparts using reported tumor scoring systems.5Tumor size larger than 5.5 cm, presence of symptoms, absence of calcifications, presence of irregular margins, and the presence of cystic degeneration or necrosis may be valuable predictors of a primary retroperitoneal malignant tumor. Although computed tomography may be used to develop a differential diagnosis of neurogenic tumors and determine the local extension, malignancy cannot accurately be determined preoperatively.6Computed tomography–guided biopsy may be unreliable because of cellular pleomorphism in areas of degeneration; hence, degenerative cells may be misinterpreted as malignancy.7

Because malignancy cannot be excluded preoperatively or even intraoperatively with frozen section analysis, complete surgical resection with partial or complete resection of adjacent viscera so as to attain negative margins is recommended.8Additionally, although rare, malignant schwannomas act like high-grade sarcomas with a high incidence of local recurrence and distant metastasis4; therefore, definitive resection for diagnosis is mandatory on suspicion of such tumors. On pathologic examination, the presence of a well-developed capsule differentiates schwannomas from the more common neurofibromas. The histologic hallmark of benign schwannomas is a pattern of alternating Antoni A and B areas, with intense staining for S100 protein.4

Fewer than 10 cases of laparoscopic resection of a retroperitoneal schwannoma have been reported in the world's literature to date. Because of the retroperitoneal schwannoma's encapsulation, a laparoscopic surgical technique is feasible. Recognition and early surgical management of retroperitoneal benign tumors, such as a schwannoma, are encouraged for appropriate diagnosis and exclusion of malignant subtypes.

Correspondence:C. Clay Cothren, MD, Department of Surgery, Denver Health Medical Center, 777 Bannock St, MC 0206, Denver, CO 80204 (clay.cothren@dhha.org).

Accepted for Publication:August 11, 2005.

Funamizu  NSasaki  AMatsumoto  T  et al.  Laparoscopic resection of a retroperitoneal schwannoma behind the lesser omental sac. Surg Laparosc Endosc Percutan Tech 2004;14175- 177
PubMed Link to Article
Antinheimo  JSankila  RCarpen  O  et al.  Population-based analysis of sporadic and type 2 neurofibromatosis-associated meningiomas and schwannomas. Neurology 2000;5471- 76
PubMed Link to Article
Gubbay  ADMoschilla  GGray  BNThompson  I Retroperitoneal schwannoma: a case series and review. Aust N Z J Surg 1995;65197- 200
PubMed Link to Article
Enzinger  FMWeiss  SW Malignant tumors of peripheral nerves. Soft Tissue Tumors. 3rd ed. St Louis, Mo Mosby1995;821- 832
Nakashima  JUeno  MNakamura  K  et al.  Differential diagnosis of primary benign and malignant retroperitoneal tumors. Int J Urol 1997;4441- 446
PubMed Link to Article
Rha  SEByun  JYJung  SEChun  HJLee  HGLee  JM Neurogenic tumors in the abdomen: tumor types and imaging characteristics. Radiographics 2003;2329- 43
PubMed Link to Article
Daneshmand  SYoussefzadeh  DChamie  K  et al.  Benign retroperitoneal schwannoma: a case series and review of the literature. Urology 2003;62993- 997
PubMed Link to Article
Giglio  MGiasotto  VMedica  M  et al.  Retroperitoneal ancient schwannoma: case report and analysis of clinico-radiological findings. Ann Urol (Paris) 2002;36104- 106
PubMed Link to Article

Figures

Place holder to copy figure label and caption
Figure 2.

A laparoscopic approach was used to dissect the inferior and lateral aspects of the well-encapsulated, solid mass well away from the renal blood vessels and ureter before rotating the entire mass out of the bed of dissection.

Graphic Jump Location

Tables

References

Funamizu  NSasaki  AMatsumoto  T  et al.  Laparoscopic resection of a retroperitoneal schwannoma behind the lesser omental sac. Surg Laparosc Endosc Percutan Tech 2004;14175- 177
PubMed Link to Article
Antinheimo  JSankila  RCarpen  O  et al.  Population-based analysis of sporadic and type 2 neurofibromatosis-associated meningiomas and schwannomas. Neurology 2000;5471- 76
PubMed Link to Article
Gubbay  ADMoschilla  GGray  BNThompson  I Retroperitoneal schwannoma: a case series and review. Aust N Z J Surg 1995;65197- 200
PubMed Link to Article
Enzinger  FMWeiss  SW Malignant tumors of peripheral nerves. Soft Tissue Tumors. 3rd ed. St Louis, Mo Mosby1995;821- 832
Nakashima  JUeno  MNakamura  K  et al.  Differential diagnosis of primary benign and malignant retroperitoneal tumors. Int J Urol 1997;4441- 446
PubMed Link to Article
Rha  SEByun  JYJung  SEChun  HJLee  HGLee  JM Neurogenic tumors in the abdomen: tumor types and imaging characteristics. Radiographics 2003;2329- 43
PubMed Link to Article
Daneshmand  SYoussefzadeh  DChamie  K  et al.  Benign retroperitoneal schwannoma: a case series and review of the literature. Urology 2003;62993- 997
PubMed Link to Article
Giglio  MGiasotto  VMedica  M  et al.  Retroperitoneal ancient schwannoma: case report and analysis of clinico-radiological findings. Ann Urol (Paris) 2002;36104- 106
PubMed Link to Article

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