Solid pseudopapillary tumor is a rare pancreatic entity, accounting for 1–3% of all pancreatic neoplasms[10]. SPT have strong sex preponderance, mainly affecting young female patients in their third or fourth decade[3, 11]. Less than 10% of patients with SPT in the reported literature were male[12]. SPT is defined as a low-grade malignant pancreatic tumor, whereas SPT have an excellent prognosis after curative resection.
Differing from its specific epidemiological characteristics, the clinical presentations of SPT are non-specific. Abdominal pain or discomfort is the most common symptom, followed by a gradually enlarging mass and compression signs induced by the tumor. For tumors larger than 3 cm, the computed tomographic image of SPT is more specific, including well-circumscribed cystic and solid masses with heterogeneous enhancement, calcification of mass, and without dilation of main pancreatic duct or parenchymal atrophy. However, for tumors smaller than 3 cm, SPT may present as a solid mass. The serum levels of carbohydrate antigen 19 − 9 and carcinoembryonic antigen in most patients were normal. Only one patient in our series presented slightly elevated carbohydrate antigen 19 − 9. Percutaneous or endoscopic fine needle aspiration may establish an accurate preoperative diagnosis[13], however, this procedure may cause tumor dissemination and pancreas inflammation[14]. Furthermore, the efficacy of fine needle aspiration was also suspected, only 11 of the 24 (46%) patients who underwent fine needle aspiration were correctly diagnosed in Kim’s study[15]. Overall, the possible diagnosis of SPT may be established by its specific epidemiological characteristics, typical radiological presentations. However, the definite diagnosis should be established basing on pathology and immunohistochemistry.
To date, the optimal treatment of SPT is completely resection[16]. Despite the increases in recognition of characteristics of this tumor, the optimal operative strategy is still controversial. The typical pancreatectomy (pancreaticoduodenectomy (PD), distal pancreatectomy) can be performed, resulting in a favorable oncological result. However, typical pancreatectomy is associated with resection a large portion of normal pancreatic parenchyma and may result in exocrine and/or endocrine deficiency[17]. Furthermore, SPT is mainly affected young patients with a long life expectancy. The detriment associated with typical pancreatectomy is more dramatic.
Enucleation of pancreatic tumor was firstly reported by Ernesto Tricomi in 1898. This procedure can maintain the normal upper digestive system anatomy and decrease the risk of post-operative exocrine and endocrine insufficiency[18]. It is widely applied in setting of pancreatic benign tumors, such as neuroendocrine tumors and cystic neoplasms[18–21]. However, laparoscopic enucleation for SPT was rarely reported in the literature. Only a few retrospective studies with small sample size were available[22–24]. Consisted with previous studies, no patient underwent enucleation in our series suffered from tumor recurrence and post-operative exocrine and endocrine insufficiency.
However, enucleation is not technically possible for all benign or border-line pancreatic tumors located in the head of pancreas [18]. If the distance between tumors and main pancreatic duct is smaller than 2 mm, enucleation should be avoided[19]. Duodenum-preserving pancreatic head resection (DPPHR) was first described by Beger in the 1980s[25]. Compared with PD, DPPHR can keep the integrity of the duodenum and biliary tract, which are beneficial to the preservation of the endocrine and exocrine function of pancreas and prevention of choledochojejunostomy complications[26]. It can provide comparable long-term oncologic outcomes[27, 28]
Considering the oncological results, no patient underwent parenchyma-sparing pancreatectomy suffered from tumor recurrence, whereas one patient underwent laparoscopic pancreaticoduodenectomy (LPD) developed liver metastases. It should be stated that this result does not mean that parenchyma-sparing pancreatectomy is associated with better oncological results. The difference may be caused by the fact that the patients underwent LPD were associated with larger tumors, pancreatic parenchymal infiltration, perineural or vascular infiltration.
The overall complications of patients underwent laparoscopic parenchyma-sparing resection were higher than that in patients underwent LPD, especially in terms of pancreatic fistula. The pancreatic fistula was more frequent in laparoscopic duodenum-preserving pancreatic head resection (LDPPHR), mainly due to LDPPHR was associated with a pancreatic cut surface and an anastomosis. Furthermore, the texture of pancreas is soft and the main pancreatic duct is not dilated, which are risk factors of post-operative pancreatic fistula.
Basing on our own experience and experience from literatures, several aspects are paramount to perform parenchyma-sparing pancreatectomy for patients with SPT located in the head of pancreas. Firstly, the lesion is thought to be SPT basing on preoperative evaluation. Tumors with suspected vascular involvement, peri-pancreatic organs involvement should be ruled out. Secondly, for patients underwent enucleation, the tumor must be at least 2 mm far from the main pancreatic duct basing on preoperative radiological findings or intraoperative ultrasonography examination; otherwise, LDPPHR is indicated. Thirdly, to ensure complete resection, enucleation should be performed by staying outside of the tumoral pseudo-capsule. Forthly, intraoperative frozen-section examination of the resected lesion and resection margins must be performed to identify the nature of the tumor and to be sure that margins are tumor free. If the frozen-section examination reports that the lesion belongs to other malignant tumor, conversion to typical pancreatectomy is required without hesitation.