Sclerosing epithelioid fibrosarcoma of the pancreas: A case report

Abstract

BACKGROUND

A sclerosing epithelioid fibrosarcoma (SEF) is a rare malignant fibroblastic soft tissue tumor that rarely occurs in intra-abdominal organs. A case of a SEF in the pancreatic head is reported herein, including its clinical manifestations, preoperative imaging features, gross specimen and pathological findings.

CASE SUMMARY

A 33-year-old male patient was admitted to Peking Union Medical College Hospital in December 2023 due to a one-year history of intermittent upper abdominal pain and the discovery of a pancreatic mass. The patient underwent an enhanced computed tomography scan of the abdomen, which revealed a well-defined, round mass with clear borders and calcifications in the pancreatic head. The mass exhibited progressive, uneven mild enhancement, measuring approximately 6.6 cm × 6.3 cm. The patient underwent laparoscopic pylorus-preserving pancreaticoduodenectomy. Postoperative pathological examination revealed that the lesion was consistent with a SEF. At the 3-month postoperative follow-up, the patient did not report any short-term complications, and there were no signs of tumor recurrence.

CONCLUSION

SEFs are rare malignant fibrous soft tissue tumors. SEFs rarely develop in the pancreas, and its preoperative diagnosis depends on imaging findings, with confirmation depending on pathological examination and immunohistochemistry. Currently, only four cases of pancreatic SEF have been reported in studies written in English. This case is the first reported case of a pancreatic SEF by a clinical physician.

Key Words: Sclerosing epithelioid fibrosarcoma of the pancreas, Abdominal malignant fibroblastic soft tissue tumor, Abdominal enhanced computed tomography, Laparoscopic pancreaticoduodenectomy, Case report

Core Tip: Sclerosing epithelioid fibrosarcoma (SEF) is a rare malignant fibroblastic soft tissue tumor, which is extremely rare in intra-abdominal organs. This article reports a case of SEF in the pancreatic head, presenting its clinical manifestations, preoperative imaging, gross specimen and pathological findings.

INTRODUCTION

Sclerosing epithelioid fibrosarcoma (SEF) is a malignant fibrous soft tissue tumor that was first reported by Meis-Kindblom et al[1]. This disease is primarily diagnosed via pathological examination and immunohistochemical (IHC) staining. SEF is generally considered a low-grade malignant tumor, but some have proposed a more aggressive clinical course. The tumor can develop at any time during the life course in males and females alike. SEFs most commonly occur in the soft tissues of the limbs, followed by the trunk and head and neck. SEFs are extremely rare in intra-abdominal organs, with only a few cases reported in the pancreas. A case of SEF in the pancreatic head, including its clinical manifestations, preoperative imaging features, gross specimen and pathological findings, are presented herein.

CASE PRESENTATION

Chief complaints

A 33-year-old male patient was admitted to Peking Union Medical College Hospital in December 2023 due to a one-year history of intermittent upper abdominal pain and the discovery of a pancreatic mass.

History of present illness

The patient had been experiencing unexplained upper abdominal pain without fever, abdominal distension, diarrhea, nausea, or vomiting. A previous abdominal ultrasound at a local hospital revealed a mass in the pancreatic head, and the patient was given oral ibuprofen for symptomatic relief. An abdominal magnetic resonance imaging (MRI) in October 2022 revealed a round mass in the pancreatic head area measuring approximately 6.4 cm × 6.1 cm × 6.6 cm (no images available). The patient experienced episodic abdominal pain every three months and responded to symptomatic treatment. A repeat abdominal ultrasound at our hospital revealed a hypoechoic mass in the pancreatic head area measuring approximately 6.6 cm × 5.6 cm × 5.7 cm, with somewhat regular morphology and uneven internal echoes. The patient was admitted for surgical treatment of a suspected pancreatic head mass.

History of past illness

There was no significant medical history, personal history, or family history.

Personal and family history

See above.

Physical examination

On admission, physical examination did not reveal any significant positive signs, and no obvious mass was palpated in the abdomen.

Laboratory examinations

Preoperative tumor marker examination revealed a carbohydrate antigen 19-9 level of 5.0 U/mL and a carcinoembryonic antigen level of 1.3 ng/mL.

Imaging examinations

Following admission, the patient underwent an enhanced computed tomography (CT) scan of the abdomen, which revealed a well-defined, round mass with clear borders and calcifications in the pancreatic head. The mass exhibited progressive, uneven mild enhancement, measuring approximately 6.6 cm × 6.3 cm. Additionally, compression and displacement were observed in the distal duodenum, gallbladder, lower segment of the inferior vena cava, and proximal segment of the superior mesenteric vein. These imaging findings suggest a potential diagnosis of a solid pseudopapillary tumor (SPT) of the pancreas. Notably, the size and morphology of the body and tail of the pancreas appeared normal, with clear margins and homogeneous parenchymal density. No significant dilation of the pancreatic duct was evident (Figure 1).

Figure 1 An enhanced computed tomography image of the abdomen revealed a mass in the head of the pancreas. A: Arterial phase; B: Portal phase; C: Portal venous system reconstruction; D: Coronal reconstruction. Blue arrow: Superior mesenteric vein; Orange arrow: Superior mesenteric artery; Green arrow: Main pancreatic duct.

TREATMENT

The patient subsequently underwent laparoscopic pylorus-preserving pancreaticoduodenectomy. Upon resection, the tumor exhibited solid characteristics, with a gray-white cut surface, hard texture, and well-defined borders, measuring 8 cm × 8 cm × 6 cm (Figure 2). Postoperatively, the patient had a smooth recovery, resumed an oral liquid diet on postoperative day (POD) 5, had all the abdominal drainage tubes removed on POD 7, and was discharged on POD 9.

Figure 2 Macroscopic photographs of the resected specimen. The tumor was solid, gray-white, hard in texture, and had roughly clear borders.

FINAL DIAGNOSIS

Postoperative pathological examination revealed that the lesion was consistent with a SEF, invading peripancreatic adipose tissue but not involving the duodenal muscular layer, common bile duct, or major duodenal papilla. The margins of the small intestine, bile duct, portal vein groove, and retroperitoneum were unremarkable, and no lymph node metastasis was observed. IHC analysis revealed positive staining for MUC4, vimentin, ATRX, SMARCA4, sporadic S-100 protein, occasional SATB2, β-catenin, partial cluster of differentiation (CD) 99, and vascular CD34 and negative staining for Cytokeratin AE1/AE3, CD10, chromogranin A, synaptophysin, B-cell lymphoma 10, tumor protein P53, SOX10, CD117, DOG-1, smooth muscle actin, desmin, Myo-D1, Myogenin, and P63, with a Ki-67 index of 30% in hot spots (Figure 3).

Figure 3 Histopathological sections of the resected specimen. A: Low × 10 and medium × 20 (inserted) magnification H and E stains demonstrating that the tumor cells are epithelioid and that mitosis is easily observed; B: Mucin 4 stain demonstrating strong and diffuse staining of the tumor cells.

OUTCOME AND FOLLOW-UP

At the 3-month postoperative follow-up, the patient did not report any short-term complications, and there were no signs of tumor recurrence.

DISCUSSION

A SEF is a rare malignant fibroblastic soft tissue tumor that can at any age. The average age at onset, as reported in various studies, is approximately 38-55 years, with an equal incidence in both men and women[1-3]. A SEF can occur in almost any soft tissue, typically affecting the limbs or trunk, followed by the intra-abdominal organs such as the liver, gastrointestinal tract, ovaries, and kidneys[4-6]. The tumor tends to grow slowly, but the average size at the time of diagnosis is 7-8 cm, and it can metastasize to the lungs, bones, and other sites[2,3,7]. SEFs rarely develop in the pancreas, with only four cases reported in studies written in English to date[8-11]. These cases were reported by departments of radiology or pathology, and this case represents the first reported case of pancreatic SEF by clinicians. A summary of the reported cases of pancreatic SEF is presented in Table 1.

Table 1 Summary of clinical data on reported pancreatic sclerosing epithelioid fibrosarcoma in the literature.

No.	Year	Author	Gender	Age	Location	Size (cm)	Clinical presentation	Surgical procedure	IHC	Ki-67 index	Follow up (m)	Recurrence
1	2013	Bai et al[8]	M	67	Body	1	None	DP and splenectomy	Vimentin (+), EMA (-), SMA (-), S-100 protein (-)	< 5%	NM	NM
2	2014	Luo et al[11]	M	42	Head	2.9	Upper abdominal pain	PD	Vimentin (+), SMA (-), S-100 protein (-), bcl-2 (-)	15%	16	None
3	2020	Xia et al[10]	M	64	Tail	2	None	DP and splenectomy	Vimentin (+), bcl-2 (+), EMA (+), SMA (+), CD34 (-), S-100 protein (-)	8% (+)	12	None
4	2020	Kramer et al[9]	M	58	Head	6	None	PPPD	MUC4 (+)	NM	3	None
5	2024	Present case	M	33	Head	8	Upper abdominal pain	Laparoscopic PPPD	MUC4 (+), Vimentin (+), SMA (-), S-100 protein (scattered +), CD34 (vessel +)	30%	2	None

IHC: Immunohistochemistry; DP: Distal pancreatectomy; CD: Cluster of differentiation; PD: pancreaticoduodenectomy; PPPD: Pylorus-preserving pancreaticoduodenectomy; NM: Not mentioned; EMA: Epithelial membrane antigen; SMA: Smooth muscle actin.

All 5 patients were male, with a median age of 58 years (range: 33-67). Two patients presented with nonspecific abdominal symptoms, such as upper abdominal pain, while the remaining patients did not report any tumor-related discomfort. SEFs can be found in the head, body, or tail of the pancreas, ranging from 1 to 8 cm in size at the time of discovery. None of the patients were diagnosed with a SEF preoperatively. In two patients with small tumors, the preoperative diagnosis was pancreatic neuroendocrine tumors[8,10], whereas in this case, the preoperative diagnosis was SPT of the pancreas. The preoperative diagnoses for the remaining two patients were not mentioned. All 5 patients underwent radical surgery (pancreaticoduodenectomy or distal pancreatectomy with splenectomy), and during the reported follow-up period, no tumor recurrence or metastasis was observed. However, one patient underwent right buttock soft tissue tumor resection 6 years prior, and upon reviewing the histological slides of the tumor, it was also considered to be a SEF. Therefore, the pancreatic lesion in this patient was considered to be a metastatic SEF[11].

SEFs are mainly diagnosed via imaging, especially enhanced CT and MRI. Imaging can provide information on the location, size, and borders of the tumor, as well as the tumor's relationship with blood vessels, bile ducts, and the main pancreatic duct and the presence of lymph node or distant metastases. On enhanced CT, SEFs appear as solid masses in the pancreas, with larger SEFs possibly showing uneven density. The enhancement pattern is characterized by gradual centripetal and nonuniform enhancement toward the center of the lesion[10]. Previously reported pancreatic SEFs often exhibit expansive growth, causing compressive and space-occupying changes to adjacent organ tissues, with direct invasion being less common. Apart from one patient with pancreatic duct dilation, the remaining patients did not show any signs of vascular invasion or pancreatic duct or bile duct dilation[11]. In this case, the large tumor caused displacement of the descending duodenum, gallbladder, lower segment of the inferior vena cava, and proximal segment of the superior mesenteric vein, as observed on preoperative images. However, intraoperative findings and postoperative pathological examination confirmed that the abovementioned organ structures were not invaded by the tumor. Notably, the typical imaging characteristics of SPTs are similar to those described above. However, SPTs predominantly develop in premenopausal women, which differs from the typical demographic characteristics of this disease. Owing to the rarity of pancreatic SEF, preoperative imaging can easily lead to misdiagnosis as primitive neurotodermal tumor, SPT, or other solid pancreatic tumors. Positron emission tomography-CT may be helpful in preoperative diagnosis, but the fludeoxyglucose (FDG) uptake of SEFs shows some heterogeneity, with different lesions exhibiting varying FDG uptake, possibly related to their different levels of invasiveness[11].

There are no studies on the value of preoperative biopsy. In this case, the patient did not undergo preoperative biopsy, mainly because the diagnosis of the pancreatic head mass was relatively clear, with preoperative images showing a SPT clearly indicated for surgical intervention. Preoperative biopsy does not alter the surgical approach and carries risks of bleeding, pancreatitis, and other complications. Pancreatic SEFs are extremely rare; thus, is it necessary to perform preoperative biopsy for differentiation? We believe that the answer to this question is complex.

The gross appearance of SEFs is typically nodular or lobulated, with a gray-white cut surface, firm or elastic consistency, and potential cystic changes and calcifications. Histologically, it is characterized by epithelioid tumor cells arranged in nests or cords that are uniformly embedded in a dense collagenous stroma. However, its tissue morphology can be easily confused with that of primary or metastatic sarcomas, SPTs of the pancreas, and other tumors. Therefore, it is typically diagnosed via immunohistochemistry. IHC staining for SEFs typically shows strong positivity for MUC4 and vimentin, whereas epithelial membrane antigen, CD34, S100 protein, and bcl-2 are weakly positive or negative[7,12]. Most cases (75%) exhibit EWSR1 gene rearrangement[7,13]. In this case, the gross specimen had a hard, gray-white cut surface, and histological examination showed epithelioid tumor cells arranged in nests and cords, with visible nuclear division. Immunohistochemistry revealed MUC4 (+), vimentin (+), S-100 (scattered +), and CD34 (vascular +), which is consistent with the above characteristics of this disease.

Although a SEF is a low-grade tumor, it typically presents aggressiveness, with a risk of local recurrence and distant metastasis. These recurrences and metastases often occur several years after initial treatment. While some patients with SEFs undergo postoperative chemotherapy, existing radiotherapy and chemotherapy have shown poor efficacy for this disease[7]. There have been reports exploring molecular targeted therapy, immunotherapy, and other potential future treatment approaches[14,15]. At present, the patient in this report has been followed for a relatively short period and has not shown signs of recurrence or metastasis, but the long-term prognosis requires further assessment. In conclusion, pancreatic SEFs are rare malignant soft tissue tumors of the pancreas with nonspecific clinical manifestations. Preoperative diagnosis is primarily based on imaging, with confirmation depending on the results of pathological examination and immunohistochemistry. Radical surgical resection is currently the main treatment method.

CONCLUSION

In conclusion, pancreatic SEFs are rare malignant soft tissue tumors of the pancreas with nonspecific clinical manifestations. Preoperative diagnosis is primarily based on imaging, with confirmation depending on the results of pathological examination and immunohistochemistry. Radical surgical resection is currently the main treatment method.