Pancreatic UPS is one of the rarest primary non-epithelial neoplasms in the pancreas, previously known as MFH [2]. The cells of origin of UPS are believed to be derived from undifferentiated mesenchymocytes, which have the capacity to differentiate into fibroblasts and tissue cells [3]. The pathological characteristics of UPS originating in the pancreas are the same as those in other parts of the body. The majority of cases compose of polymorphy tumors, characterized by cytological and nuclear pleomorphism, mixed with different ratios of spindle cells [4]. They were previously divided into storiform-pleomorphic, inflammatory, giant cell, myxoid, and angiomatoid subtypes [5–6]. However, in the most recent version of the World Health Organization (WHO) classification, UPS only represents the correct label for the prototypical storiform and pleomorphic variant of MFH [7]. We searched PubMed from the establishment of the database to August 2021, and finally only enrolled 16 cases, including the present case. Therefore, it is important to report the type of tumor morphology for this relatively unknown malignancy.
The clinicopathological profiles of these patients are summarized in Table 1. Among these 16 cases, the ratio of male to female was 12:4. The median age at diagnosis was 57 years. Primary UPS happens to different parts of the pancreas. Nine cases of tumors were located in the body of the pancreas and/or tail of the pancreas, and underwent left pancreatectomy and splenectomy. In 6 cases, it occured at the pancreatic head and pancreaticoduodenectomy was performed. The preoperative diagnosis of all patients was not clear. Of the 16 cases reported, 11 patients had no further adjuvant therapy. Two patients received adjuvant radiotherapy and chemotherapy and three patients received adjuvant chemotherapy. The longest postoperative follow-up survival time was 48 months.
Table 1
Clinical data of the 16 patients with pancreatic UPS
First author | Age | Sex | Histologic type | Location | Treatment | Preoperative diagnosis | Postoperative therapy | Follow-up (months) |
Ishiguchi, et al. [8] | 44 | M | Pleomorphic | Body-tail | Left pancreatectomy, splenectomy | pancreatic neoplasms | NA | 15, NED |
Garvey, et al. [9] | 77 | M | Storiform-pleomorphic | Uncinate lobe | Enucleation | Pancreatic head mass | NA | 48, NED |
Pascal, et al. [3] | 39 | M | Storiform-pleomorphic | Head | Pancreaticoduodenectomy | mesenchymal tumor | NA | 0, DOC |
Allen, et al. [10] | 46 | M | Storiform-pleomorphic | Body-tail, local invasion | pancreatectomy, splenectomy, subtotal gastrectomy | NA | chemotherapy | 5, DOD |
Tsujimura, et al. [11] | 43 | F | Storiform-pleomorphic | Tail | Pancreatectomy, splenectomy | Pancreatic cystadenoma | chemotherapy | 5, NED |
Ben Jilani, et al. [12] | 72 | M | Storiform-pleomorphic | Body-tail | Left pancreatectomy, splenectomy | Pancreatic mass | NA | 12, DOD |
Balen, et al. [13] | 37 | M | Pleomorphic | Body-tail | Extended left pancreatectomy | Pancreatic mass | Radiotherapy and chemotherapy | 7, DOD |
Haba, et al. [14] | 70 | M | Storiform-pleomorphic | Head | Pancreaticoduodenectomy | Tumor of pancreatic head | chemotherapy | 22, NED |
Bastian, et al. [15] | 67 | M | Storiform-pleomorphic | Body | Left pancreatectomy, splenectomy, transverse colectomy, subtotal gastrectomy | Pancreatic cancer | NA | 34, NED |
Darvishian, et al. [16] | 74 | M | Storiform-pleomorphic | Head | Pancreaticoduodenectomy | Pancreatic head cancer | NA | 4, NED |
Akatsu, et al. [17] | 67 | M | Storiform-pleomorphic | Body-tail | Left pancreatectomy, splenectomy, transverse colectomy, total gastrectomy | Pancreatic cancer | NA | 35, NED |
Mizukami, et al. [18] | 44 | F | Pleomorphic | Body-tail | Total gastrectomy, left pancreatectomy | Pancreatic tumor | NA | 20, NED |
Yu, et al. [19] | 67 | M | Storiform-pleomorphic | Head | Pancreaticoduodenectomy | Pancreatic head cyst | NA | 11, DOD |
Jarry, et al. [4] | 45 | M | Storiform-pleomorphic | Head | Pancreaticoduodenectomy | Pancreatic cancer | Radiotherapy and chemotherapy | 36, NED |
Sanei, et al. [1] | 72 | F | Pleomorphic | Head and neck | Pancreaticoduodenectomy | Pancreatic head cancer | NA | 22, NED |
Own case | 37 | F | Pleomorphic | Body-tail | Distal pancreatectomy | Pancreatic mass | NA | 12, DOD |
Pancreatic UPS grows fast, and its clinical features described in literature are varied, but upper abdominal discomfort are the most common presentation. At present, there is no reliable laboratory test contributing to diagnosis, and the preoperative tumor markers in this case are negative. In the previous reports, pancreatic UPS presented a large, nonhomogeneous, hypointense or multinodular lesion with possible intratumoral calcification [20] and massive liquescent necrosis in CT plain scan [15,17]. Enhanced modalities showed a non-homogeneously enhancing mass with enhancing peripheral pseudocapsular [19]. The case reported by Yu et al. [19] showed a huge multilocular cystic lesion on abdominal CT and MRI, which contained a large amount of liquefaction necrosis, and the cyst wall, fibrous septum, and solid components were enhanced. Miller et al. [21] found that internal low-intensity separation on MRI and nonhomogeneous high-intensity on T2-weighted images were the general characteristics of malignant soft tissue tumors. The preoperative CT and MRI of our patient showed cystic or cystic solid pancreatic masses with blood deposition. A low signal region on T2-weighted images that reflected the fibrous element was also observed in our patient, which was similar to the case reported by Yu et al., but there was no obvious enhancement in each phase. As we know, we depict the first case of primary UPS of the pancreas with ultrasound examination findings. The author believes that for ultrasound diagnosis of cystic solid pancreatic mass, the possibility of malignant lesions should be considered for those with thick and uneven wall thickness and mixed solid echo and cystic echo within the lesion.
In general, it is difficult to diagnose pancreatic UPS without obtaining tumor tissues. Endoscopic ultrasonography-guided needle aspiration has become the most accurate method for the diagnosis of pancreatic malignant tumors [22]. However, in order to prevent tumor spread and needle implantation, a routine preoperative biopsy is not recommended. For patients who are difficult to identify and require radiotherapy or chemotherapy, puncture can be performed for pathological examination. Immunohistochemical examination can rule out other types of sarcoma and ultimately confirm the diagnosis of UPS. The pathological differential diagnosis among the pancreatic neoplasms includes leiomyosarcomas, liposarcomas, neurogenic sarcomas and malignant lymphomas which have respective tumor markers[17, 23–24]. UPS is reserved only for those soft tissue sarcomas which do not show any definitive line of differentiation. The present case showed positive staining for vimentin, CD68, and p53, negative for S-100, SMA, desmin, or CEA was observed, which differentiates this neoplasm from other sarcomas. Previous studies have pointed out that UPS exhibits strong responses to vimentin and CD68 as this case did [25–26]. Mizukami et al [18] concluded that positivity for p53 in the tumor cells may be helpful in distinguishing the UPS from pseudotumors such as inflammatory pseudotumors.
Primary pancreatic UPS appears to parallel the biological behavior of retroperitoneal UPS. Thus, the therapy of pancreatic UPS can follow the treatment principles of the latter. Radical resection is the mainstay method and the choice of surgical method depends on the location of the tumor. Due to the short follow-up period of previous studies, the final prognosis after surgical excision is hard to evaluate. In the case here described, the preoperative laboratory examination and intraoperative gross specimens revealed benign lesions. Considering that the patient was young, pancreatic body and tail resection was performed to preserve pancreatic function. However, postoperative pathological examination and immunohistochemistry confirmed the diagnosis of pancreatic primary UPS. The poor outcome of the current case may be due to incomplete resection as well as to the biological malignant potential. Through the diagnosis and treatment of this patient, we have learned many lessons: (1) Although rare, UPS of pancreas is essential to consider when making a differential diagnosis in a patient with a cystic solid pancreatic lesion. (2) For patients who fail to obtain histological examination before operation, an intraoperative frozen examination should be carried out as much as possible to reduce the missed diagnosis of pancreatic malignant tumors. (3) If the initial surgery is not complete, radical surgery should be performed again in time to achieve an R0 situation.
In addition to surgery, radiotherapy may have a certain effect on pancreatic UPS. Study have found that when the tumor cannot be completely removed, radiotherapy is an important adjuvant treatment for UPS in other parts.[27] However, due to the limited number, the role of adjuvant radiotherapy on these tumors has not been determined. Chemotherapy has been reported to effectively prolong survival for patients with UPS in the soft tissue. Doxorubicin and ifosfamide are usually recommended as the first-line chemotherapy regimen for soft tissue sarcoma [28], but based on the existing literature, which regimen should be adopted for pancreatic UPS are still being explored. Jarry et al[4] report a case of resected pancreatic UPS who recurred 11 months later presenting as pulmonary and hepatic metastasis. The patient underwent a multidisciplinary therapy of radiofrequency ablation, chemotherapy, and a right hepatectomy. Then, The patient recovered completely and was disease-free for 3 years after the operation. It seems that such treatment could improve the survival rates of recurring patients.