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Special Feature |

Image of the Month—Diagnosis FREE

[+] Author Affiliations

Section Editor: Carl E. Bredenberg, MD

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Arch Surg. 2010;145(9):914. doi:10.1001/archsurg.2010.172-b.
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Published online

Schwannoma (neurilemoma) is a benign tumor of neural crest–derived Schwann cells usually found on the extremities.14 Pancreatic schwannomas are exceedingly rare and are thought to arise from either autonomic sympathetic or parasympathetic fibers coursing through the pancreas.2,5 In contrast, neurofibromas, which can be associated with neurofibromatosis 1, have a greater chance for malignant degeneration.4

Microscopically, schwannomas are well-circumscribed, encapsulated tumors with a mixture of 2 growth patterns: Antoni A and Antoni B. The Antoni A pattern contains areas of high cellularity with spindle cells arranged in a palisading fashion and areas of low cellularity between the palisades called Verocay bodies. Antoni B areas have a hypodense cellularity with a loose meshwork of cells. If these areas show degenerative changes, such as cyst formation, stromal hemorrhage, hyalinization, calcification, and nuclear atypia, they are called ancient schwannomas.1,5,6 The present case did have areas with degenerative changes consistent with an ancient schwannoma (Figure 2B).

Place holder to copy figure label and caption
Figure 2.

Histology of the resected specimen showing an encapsulated neoplasm within the pancreas composed of spindle cells. A, Nerve fibers are adjacent to and within the fibrous capsule (hematoxylin-eosin staining, original magnification ×40). B, The nuclei demonstrated significant atypia focally (hematoxylin-eosin, original magnification ×400). C, Verocay bodies (rows of nuclei with intervening cell processes) were present (hematoxylin-eosin, original magnification ×200). D, An immunohistochemical stain for S-100 shows diffuse nuclear and cytoplasmic staining (polyclonal S-100, original magnification ×100). These findings are consistent with the diagnosis of ancient schwannoma.

Graphic Jump Location

On CT scan, tumors with predominately Antoni A areas appear as inhomogeneous hypodense masses with contrast enhancement. The hypodensity is caused by the high lipid content, while the contrast enhancement can be attributed to the hypervascularization of the tumor.6,7 Tumors with predominately Antoni B areas may have a cystic or multiseptated appearance on CT scan caused by the poor cellularity and loose stroma.8 The present case contained both Antoni A and B areas and appeared to be a septated partially cystic mass on ultrasonography (not shown), which was enhanced with contrast on CT scan (Figure 1). Immunohistochemistry can help provide a definitive diagnosis of pancreatic schwannoma. The spindle cells of schwannomas will stain diffusely positive for S-100 antibodies (Figure 2D).1,3

Place holder to copy figure label and caption
Figure 1.

Preoperative computed tomographic scan showing a 1.4-cm enhancing lesion in the head of the pancreas.

Graphic Jump Location

Only 40 cases of pancreatic schwannoma have been reported in the English and European literature. Most (40%) are located in the pancreatic head.4 It is no surprise that preoperative diagnosis of pancreatic schwannoma is uncommon, and the diagnosis is usually made after a Whipple procedure to remove the mass, as in the present case. The preoperative imaging characteristics of pancreatic schwannoma can be similar to adenocarcinoma, nonfunctioning islet cell tumor, and mucinous cystadenoma.2,9 Fasanella et al10 recently reported the first case of a pancreatic schwannoma diagnosed preoperatively by endoscopic ultrasonography and fine needle aspiration. A preoperative diagnosis may allow a less aggressive resection.9,10 In the present case, the chronic nature of the patient's pain, lack of duct dilation, and the well-circumscribed enhancing appearance of the lesion on imaging all suggested that the diagnosis was less likely to be adenocarcinoma. If preoperative endoscopic ultrasonography and fine needle aspiration had indicated a diagnosis, enucleation may have been appropriate because the tumor did not involve the main pancreatic duct.11 In the literature there have been no reports of local recurrence or metastasis of pancreatic schwannomas.

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Submissions

Due to the overwhelmingly positive response to the Image of the Month, the Archives of Surgery has temporarily discontinued accepting submissions for this feature. Requests for submissions will resume in January 2011. Thank you.

Correspondence: William E. Fisher, MD, Elkins Pancreas Center, Micheal E. DeBakey Department of Surgery, Baylor College of Medicine, 1709 Dryden, Ste 1500, Houston, TX 77030 (wfisher@bcm.edu).

Accepted for Publication: July 13, 2010.

Author Contributions:Study concept and design: Dorsey and Fisher. Acquisition of data: Dorsey, Taggart, and Fisher. Analysis and interpretation of data: Dorsey, Taggart, and Fisher. Drafting of the manuscript: Dorsey, Taggart, and Fisher. Critical revision of the manuscript for important intellectual content: Fisher. Administrative, technical, and material support: Dorsey, Taggart, and Fisher. Study supervision: Fisher.

Financial Disclosure: None reported.  

Kumar  VAbbas  AFausto  N Robbins and Cotran Pathologic Basis of Disease. 7th ed. Philadelphia, PA: Elsevier; 2005
Paranjape  CJohnson  SRKhwaja  KGoldman  HKruskal  JBHanto  DW Clinical characteristics, treatment, and outcome of pancreatic Schwannomas. J Gastrointest Surg 2004;8 (6) 706- 712
PubMed Link to Article
Almo  KMTraverso  LW Pancreatic schwannoma: an uncommon but important entity. J Gastrointest Surg 2001;5 (4) 359- 363
PubMed Link to Article
Di Benedetto  FSpaggiari  MDe Ruvo  N  et al.  Pancreatic schwannoma of the body involving the splenic vein: case report and review of the literature. Eur J Surg Oncol 2007;33 (7) 926- 928
PubMed Link to Article
Tan  GVitellas  KMorrison  CFrankel  WL Cystic schwannoma of the pancreas. Ann Diagn Pathol 2003;7 (5) 285- 291
PubMed Link to Article
Akiyoshi  TUeda  YYanai  K  et al.  Melanotic schwannoma of the pancreas: report of a case. Surg Today 2004;34 (6) 550- 553
PubMed Link to Article
Novellas  SChevallier  PSaint Paul  MCGugenheim  JBruneton  JN MRI features of a pancreatic schwannoma. Clin Imaging 2005;29 (6) 434- 436
PubMed Link to Article
Morita  SOkuda  JSumiyoshi  K  et al.  Pancreatic schwannoma: report of a case. Surg Today 1999;29 (10) 1093- 1097
PubMed Link to Article
Soumaoro  LTTeramoto  KKawamura  T  et al.  Benign schwannoma of the pancreas. J Gastrointest Surg 2005;9 (2) 288- 290
PubMed Link to Article
Fasanella  KELee  KKKaushik  N Clinical challenges and images in GI: benign schwannoma of the pancreatic head. Gastroenterology 2007;132 (2) 489- 830, 830
PubMed Link to Article
Wu  YLYan  HCChen  LRChen  JGao  SLLi  JT Pancreatic benign schwannoma treated by simple enucleation: case report and review of literature. Pancreas 2005;31 (3) 286- 288
PubMed Link to Article

Figures

Place holder to copy figure label and caption
Figure 2.

Histology of the resected specimen showing an encapsulated neoplasm within the pancreas composed of spindle cells. A, Nerve fibers are adjacent to and within the fibrous capsule (hematoxylin-eosin staining, original magnification ×40). B, The nuclei demonstrated significant atypia focally (hematoxylin-eosin, original magnification ×400). C, Verocay bodies (rows of nuclei with intervening cell processes) were present (hematoxylin-eosin, original magnification ×200). D, An immunohistochemical stain for S-100 shows diffuse nuclear and cytoplasmic staining (polyclonal S-100, original magnification ×100). These findings are consistent with the diagnosis of ancient schwannoma.

Graphic Jump Location
Place holder to copy figure label and caption
Figure 1.

Preoperative computed tomographic scan showing a 1.4-cm enhancing lesion in the head of the pancreas.

Graphic Jump Location

Tables

References

Kumar  VAbbas  AFausto  N Robbins and Cotran Pathologic Basis of Disease. 7th ed. Philadelphia, PA: Elsevier; 2005
Paranjape  CJohnson  SRKhwaja  KGoldman  HKruskal  JBHanto  DW Clinical characteristics, treatment, and outcome of pancreatic Schwannomas. J Gastrointest Surg 2004;8 (6) 706- 712
PubMed Link to Article
Almo  KMTraverso  LW Pancreatic schwannoma: an uncommon but important entity. J Gastrointest Surg 2001;5 (4) 359- 363
PubMed Link to Article
Di Benedetto  FSpaggiari  MDe Ruvo  N  et al.  Pancreatic schwannoma of the body involving the splenic vein: case report and review of the literature. Eur J Surg Oncol 2007;33 (7) 926- 928
PubMed Link to Article
Tan  GVitellas  KMorrison  CFrankel  WL Cystic schwannoma of the pancreas. Ann Diagn Pathol 2003;7 (5) 285- 291
PubMed Link to Article
Akiyoshi  TUeda  YYanai  K  et al.  Melanotic schwannoma of the pancreas: report of a case. Surg Today 2004;34 (6) 550- 553
PubMed Link to Article
Novellas  SChevallier  PSaint Paul  MCGugenheim  JBruneton  JN MRI features of a pancreatic schwannoma. Clin Imaging 2005;29 (6) 434- 436
PubMed Link to Article
Morita  SOkuda  JSumiyoshi  K  et al.  Pancreatic schwannoma: report of a case. Surg Today 1999;29 (10) 1093- 1097
PubMed Link to Article
Soumaoro  LTTeramoto  KKawamura  T  et al.  Benign schwannoma of the pancreas. J Gastrointest Surg 2005;9 (2) 288- 290
PubMed Link to Article
Fasanella  KELee  KKKaushik  N Clinical challenges and images in GI: benign schwannoma of the pancreatic head. Gastroenterology 2007;132 (2) 489- 830, 830
PubMed Link to Article
Wu  YLYan  HCChen  LRChen  JGao  SLLi  JT Pancreatic benign schwannoma treated by simple enucleation: case report and review of literature. Pancreas 2005;31 (3) 286- 288
PubMed Link to Article

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