Case Report Open Access
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World J Gastrointest Surg. Jun 27, 2016; 8(6): 461-466
Published online Jun 27, 2016. doi: 10.4240/wjgs.v8.i6.461
Solitary fibrous tumor of the pancreas: Case report and review of the literature
Daniel Paramythiotis, Konstantinia Kofina, Petros Bangeas, George Basdanis, 1st Propedeutic Surgical Clinic, A.H.E.P.A. University Hospital, Aristotle’s University of Thessaloniki, 54636 Thessaloniki, Greece
Fani Tsiompanou, Georgia Karayannopoulou, Department of Pathology, Aristotle’s University of Thessaloniki, 54636 Thessaloniki, Greece
Author contributions: Paramythiotis D and Basdanis G designed the report; Kofina K analyzed the data and wrote the paper; Bangeas P collected the patient’s clinical data; Tsiompanou F and Karayannopoulou G performed the histological examination.
Institutional review board statement: This case report was approved by the A.H.E.P.A. University Hospital Institutional Review Board.
Informed consent statement: The patient provided informed consent prior to the review.
Conflict-of-interest statement: All authors declare no conflict of interest.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Daniel Paramythiotis, MD, MSc, PhD, Assistant Professor of Surgery, 1st Propedeutic Surgical Clinic, A.H.E.P.A. University Hospital, Aristotle’s University of Thessaloniki, L. Tzavella 2D, Pilea, 54636 Thessaloniki, Greece. danosprx1@hotmail.com
Telephone: +30-6944-906619 Fax: +30-2310-994784
Received: June 28, 2015
Peer-review started: July 11, 2015
First decision: August 24, 2015
Revised: March 1, 2016
Accepted: March 17, 2016
Article in press: March 18, 2016
Published online: June 27, 2016
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Abstract

Solitary fibrous tumor (SFT) is a mesenchymal tumor typically located in the pleura, but can also be found as an asymptomatic mass in other areas, including the liver, peritoneum, kidney and salivary glands. However, SFT rarely locates in the pancreas. We present such a case of pancreatic SFT, along with a review of all reported cases. A 55-year-old man was treated surgically for an asymptomatic pancreatic mass after a rigorous preoperative control. Histologic examination of the resected specimen showed characteristics of an SFT. As only 15 cases of pancreatic SFT have been reported so far, an attempt to compare the cases was considered intriguing. We found that patients with pancreatic SFT were mainly women (81.25%), with a median age of 54 years at the time of diagnosis and a median tumor size of 5.83 cm. Pancreatic SFTs were revealed incidentally in 50% of cases, and all of them showed an enhancement through arterial computed tomography. All tumors were positive for CD34, ten were positive for Bcl-2, and twelve were negative for S100. The diagnosis of this pancreatic tumor is established by a combination of clinical suspicion, imaging procedures and histological findings, and is confirmed by immunohistochemical staining. Although the behavior of SFTs is rather benign, close clinical follow-up is recommended due to a potentially malignant nature.

Key Words: Solitary fibrous tumor; Pancreas; Mesenchymal tumors; Differential diagnosis; Solitary fibrous tumor treatment

Core tip: Solitary fibrous tumor (SFT) is a mesenchymal tumor that rarely locates in the pancreas. We present the case of a 55-year-old man with a pancreatic lesion that proved to be an SFT after thorough pre- and post-operative control. The characteristics of this case and the other fifteen cases of pancreatic SFT reported in the literature are described.



INTRODUCTION

Solitary fibrous tumor (SFT) was described as a distinct type of mesenchymal tumor for the first time at 1931[1]. SFT can be benign or malignant and is typically located in the pleura, but the tumor can also be found as an asymptomatic mass in other areas such as the liver, peritoneum, kidney and salivary glands[2-4]. SFTs often occur in middle age (40-70 years), especially in the fifth decade of life, and metastases can be detected in 10% to 15% of the cases[4-6]. This type of tumor appears very rarely in the pancreas, as only 15 cases have been reported so far.

CASE REPORT

A 55-year-old man was admitted in our surgical department for further evaluation of an asymptomatic pancreatic mass that had been found incidentally by upper abdomen ultrasonography. No specific symptoms were mentioned except vague abdominal pain. Clinical examination and laboratory results were unremarkable, and the levels of tumor markers (CEA, CA 19-9, CA 15-3) were within normal ranges. The patient’s medical history included coronary heart disease (one myocardial infarction and coronary artery bypass surgery seven years ago), open cholecystectomy (27 years ago), choledocholithiasis treated with endoscopic retrograde cholangiopancreatography (5 years ago), dyslipidemia and hypertension under medication.

During ultrasound examination of the abdomen for non-specific pain, a hypoechoic solid mass of 2.8 cm × 3.1 cm on the pancreatic body (Figure 1) and a possible dilation of the common bile duct were found. Further imaging was performed. Computed tomography (CT) scans revealed a 3.9-cm-diameter exophytic mass arising from the pancreatic body that was enhanced from the arterial to portal venous phase (Figure 2). T1-weighted magnetic resonance imaging (MRI) scans showed a hypointense mass. Regional lymphadenopathy was not found on the CT or MRI images. Magnetic resonance cholangiopancreatography imaging revealed a pancreatic body cystic portion with heterogeneous internal echogenicities of mixed substantial and necrotic parts. Although the main pancreatic duct was not dilated, the common bile duct displayed a filling deficit. The upper digestive tract endoscopy showed no abnormalities.

Figure 1
Figure 1 Ultrasound echo showing a 2. 8 cm × 3.1 cm hypoechoic solid mass located on the pancreatic body.
Figure 2
Figure 2 Computed tomography scan revealing a 3. 9 cm exophytic mass, arising from the pancreatic body, which was enhanced from the arterial to portal venous phase.

Based on the above findings, we considered that the differential diagnosis of the mass should include exophytic non-functioning islet tumor, solid pseudopapillary mass of the pancreas, gastrointestinal stromal tumor (GIST), neuroendocrine tumor and hemangiopericytoma of the pancreas.

The surgical removal of the mass was considered necessary and the patient underwent a pancreatectomy including body and tail, whereas the spleen was maintained. The resected mass measured 3.6 cm in its greatest diameter and had an ovoid shape with well-capsulated, smooth margins and a yellowish-grey hue (Figures 3 and 4). The abdominal exploration did not show any signs of metastasis or tumor infiltration into neighboring organs.

Figure 3
Figure 3 Intra-operative appearance of the pancreatic mass.
Figure 4
Figure 4 Pancreatic mass specimen.

On histopathological examination, the mass showed characteristics of a neoplasm, including spindle-shaped tumor cells with elongated nuclei. Mitoses were scarce. The neoplasm presented a storiform pattern with alternating hypocellular and hypercellular areas, and some areas showed myxoid degeneration. There were a large number of blood vessels within the stroma (Figure 5).

Figure 5
Figure 5 Solitary fibrous tumor with a hyalinized area, HE stain. Magnification: × 400 .

Immunohistochemically, the tumor cells were positive for CD34, CD99, Bcl-2 (Figure 6) and vimentin, and exhibited focal positivity for S-100 protein. Only a small number of cells were positive for the cell proliferation marker Ki-67/MIB-1. The tumor cells were negative for smooth muscle actin (SMA), keratin, cytokeratin (AE1/AE3), CD117, epithelial membrane antigen and desmin. The final diagnosis was pancreatic SFT with a low grade of malignancy.

Figure 6
Figure 6 Immunohistochemical staining (brown) for CD34 (A), CD99 (B) and Bcl-2 (C). Magnification: × 400.

After surgery, the patient was led to the intensive care unit. His post-operative course was uneventful and he was discharged on the 9th postoperative day with the recommendation to follow a non-fat diet. Chemotherapy was not considered necessary. In the 6- and 12-mo follow-up periods the patient was asymptomatic and in good health.

DISCUSSION

Mesenchymal tumors of the pancreas include leiomyosarcoma, peripheral nerve tumors, fibro-histiocytic tumors and vascular tumors[7-9]. Differential diagnosis is based on histology and immunohistochemistry findings and, therefore, diagnosis is often very difficult before surgery.

On the other hand, pancreatic SFTs are very rare, as only 16 cases have been reported in the literature[1,3-16], including our case. The patients were mainly women (13/16, 81.25%), with a median age of 54 years at the time of diagnosis (range: 24-78 years, median age: 50 years for males, 55.46 years for females) and a median tumor size of 5.83 cm (range: 1.5-18.5 cm). In six cases the tumor was located in the pancreatic body (37%) and in seven cases the tumor was located in the pancreatic head (43.75%) (Table 1). The tumor was revealed incidentally in half the cases; however, in the other half, the main symptom was pain (jaundice was presented in only one case). Regarding imaging, all tumors showed an enhancement through arterial and portal CT. The results of MRI imaging were described for seven cases: These tumors were hypointense in T1-weighted images and hyperintense in T2-weighted images (Table 2).

Table 1 Characteristics of patients with solitary fibrous tumor of the pancreas.
Ref.SexAgeSymptomsSize (cm)Location
Lüttges et al[4]Female50Incidental5.5Body
Chatti et al[8]Male41Pain13Body
Gardini et al[10]Female62Pain3Head
Miyamoto et al[9]Female41Pain2Head-body
Srinivasan et al[5]Female78Pain, weight loss5Body
Kwon et al[7]Male54Incidental4.5Body
Ishiwatari et al[11]Female58Incidental3Head
Chetty et al[3]Female67Incidental2.6Body
Sugawara et al[6]Female55Incidental7Head
Santos et al[12]Female40Incidental3Body
Tasdemir et al[1]Female24Incidental18.5Head
van der Vorst et al[13]Female67Pain2.8Uncinate process
Chen et al[14]Female49Pain, distension, appetite loss13Head
Hwang et al[15]Female53Incidental5.2Head
Hee Han et al[16]Female77Jaundice1.5Head
Paramythiotis et alMale55Pain3.6Body
Table 2 Imaging features of pancreatic Solitary fibrous tumors.
Ref.Arterial CTVenous CTMRI T1MRI T2
Lüttges et al[4]EnhancedEnhanced
Chatti et al[8]EnhancedEnhancedHypointenseHyperintense
Gardini et al[10]EnhancedEnhanced
Miyamoto et al[9]EnhancedEnhanced
Srinivasan et al[5]Hyper-enhancedEnhanced
Kwon et al[7]EnhancedEnhancedHypointenseHyperintense
Ishiwatari et al[11]EnhancedEnhancedHypointenseHyperintense
Chetty et al[3]EnhancedEnhanced
Sugawara et al[6]EnhancedEnhancedHypointenseHyperintense
Santos et al[12]
Tasdemir et al[1]EnhancedEnhanced
van der Vorst et al[13]EnhancedEnhanced
Chen et al[14]EnhancedEnhanced
Hwang et al[15]EnhancedEnhancedHypointenseHyperintense
Hee Han et al[16]EnhancedEnhancedHypointenseHyperintense
Paramythiotis et alEnhancedEnhancedHypointenseHyperintense

All cases were treated surgically except for one case which was diagnosed after biopsy. By immunohistochemistry, all tumors were positive for CD34, ten tumors were positive for Bcl-2, and only one tumor was positive for S100. Many tumors were positive for keratin types. Controls for CD117 (1 positive, 10 negatives), CD19 (11 positives, 1 negative) and SMA (4 positives, 5 negatives) didn’t show the same results in all cases (Table 3).

Table 3 Treatment and immunohistochemistry findings.
Ref.SurgeryImmunohistochemistry
Lüttges et al[4]Distal pancreatectomyPositive: CD34, CD99, Bcl-2, vimentin Negative: SMA, S100
Chatti et al[8]EnuclationPositive: CD34, CD99 (focal), Bcl-2, SMA (focal), CD117 (focal) Negative: EMA, cytokeratin, S100
Gardini et al[10]Traverso-longmirePositive: CD34, CD99, Bcl-2, vimentin, smooth muscle actin (focal) Negative: Desmin, CD117, S100
Miyamoto et al[9]Head-body junctionPositive: CD34, Bcl-2 Negative: cytokeratin, CAM 5.2, SMA, desmin, S100, CD117
Srinivasan et al[5]Distal pancreatectomyPositive: CD34 (focal), CD99, Bcl-2, vimentin Negative: CAM 5.2, SMA, desmin, CD117, CD10, chromogranin, S100
Kwon et al[7]Median segmentectomyPositive: CD34 , CD99 Negative: CD117, S100
Ishiwatari et al[11]PancreaticoduodenectomyPositive: CD34, Bcl-2 Negative: S100
Chetty et al[3]WhipplePositive: CD34, CD99, Bcl-2
Sugawara et al[6]PancreaticoduodenectomyPositive: CD34 Negative: SMA, S100, CD117, ALK, cytokeratin
Santos et al[12]Partial pancreatectomyPositive: CD34, b-catenin Negative: C-kit
Tasdemir et al[1]EnuclationPositive: CD34, vimentin, SMA (focal) Negative: S100, CD117, desmin, cytokeratin
van der Vorst et al[13]EnuclationPositive: CD34, CD99, Bcl-2 Negative: CD117, b-catenin
Chen et al[14]Whipple/childPositive: CD34, CD68, MSA, Bcl-2, Ki-67 Negative: SMA, cytokeratin, desmin, CD117, CD99, S100
Hwang et al[15]Partial head resectionPositive: CD34, CD99, Bcl-2, SMA, CD10, ER, PR Negative: CD117, DOG-1, caldemon, desmin, EMA, S100, cytokeratin
Hee Han et al[16]Echo-guided needle biopsyPositive: CD34, CD99 Negative: C-kit, S100
Paramythiotis et alDistal pancreatectomyPositive: CD34, CD99, Bcl-2, vimentin, S100 (focal) Negative: SMA, keratin, cytokeratin, CD117, EMA and desmin

Most pancreatic SFTs presented as well-circumscribed, often partially-encapsulated masses[9] with a multinodular, whitish and firm appearance. On microscope sections, the tumors showed a patternless architecture characterized by alternating hypocellular and hypercellular areas separated by thick bands of collagen and branching hemangiopericytoma-like vessels[6]. The tumor cells were round-to-spindle-shaped and the mitoses were scarce. Tumor necrosis and infiltrative margins were observed in malignant neoplasms occurring in other locations.

The differential diagnosis of SFT includes leiomyosarcoma, liposarcoma, fibrosarcoma, fibrous histiocytoma, hemangioendothelioma, hemangiopericytoma, hemangioma, lymphangioma, islet cell tumor, paraganglioma, neuroectodermal tumor, and schwannoma[12]. The main diagnostic consideration based on imaging findings is thought to be endocrine neoplasms[3,5]. These are composed of round cells with granular, eosinophilic cytoplasm and are positive for synaptophysin and chromogranin. As leiomyosarcomas are considered to be more frequent than SFTs in the pancreas, the former must be differentiated by their nuclear atypia and increased mitotic activity[1,5]. Moreover, GISTs are positive for CD34, vimentin and CD117 but SFTs are negative for CD117 [1,5,9].

In our case, preoperative CT and MRI scans strongly showed the typical pattern of SFTs[15]. Histopathological examination of the resected tumor revealed that it was covered with a fibrous capsule and contained necrotic tissue, favoring the diagnosis of SFT. Immunohistochemistry findings confirmed the diagnosis.

The diagnosis of pancreatic SFT is established from a combination of clinical suspicion (mainly women of middle age, with abdominal pain and nonspecific symptoms), imaging procedures (ultrasound, CT and MRI) and histological findings, and is confirmed by immunohistochemistry. Although SFTs are usually benign, clinical follow-up is recommended because these tumors can become malignant[1,5].

COMMENTS
Case characteristics

Asymptomatic 55-year-old male.

Clinical diagnosis

Abdominal pain.

Differential diagnosis

Upper abdomen tumors.

Imaging diagnosis

Exophytic mass of the pancreatic body.

Pathologic diagnosis

Pancreatic solitary fibrous tumor (SFT).

Treatment

Pancreatectomy (body and tail).

Related reports

Fifteen case reports of this rare condition.

Term explanation

Mesenchymal tumors arise from mesodermally-derived tissues, and can be either benign or malignant.

Experiences and lessons

This report discusses the basic characteristics of pancreatic SFTs, based on all the cases reported so far.

Peer-review

The authors report a case of a rare pancreatic tumor and compare it to cases in the existing bibliography.

Footnotes

P- Reviewer: Kai K, Sakata N S- Editor: Kong JX L- Editor: A E- Editor: Wu HL

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