Solid pseudopapillary tumour should be part of differential diagnosis of focal pancreatic lesions with increased 18 F-FDOPA uptake

OBJECTIVE

To assess the specificity of increased ¹⁸ F-dihydroxyphenylalanine (¹⁸ F-FDOPA) uptake in patients who underwent PET/CT for suspicion of isolated pancreatic neuroendocrine tumour (pNET). False-positive results mimicking a pNET have been investigated.

MATERIAL AND METHODS

Carbidopa-assisted ¹⁸ F-FDOPA PET/CT scans performed in patients with suspicion of localized pNET were retrieved. Only patients with a definitive diagnosis were retrospectively included. When available, the histopathological result after pancreatic surgery was the gold standard. In other cases, the diagnosis was based on endoscopic ultrasonography (EUS)/cytology and/or on concordant imaging results of at least two of the following: contrast-enhanced computed tomography (CE-CT), magnetic resonance imaging (MRI) and somatostatin receptor scintigraphy (SRS).

RESULTS

Forty-four among 731 patients were selected. Among these, 36 patients (82%) were surgically treated, revealing pNET (n = 28), solid pseudopapillary tumour (SPT) (n = 4), adenocarcinoma (n = 2), serous cystadenomas (n = 1) and solitary fibrous tumour (n = 1) cases. An additional three cases of pNET were diagnosed by EUS/cytology. In the remaining five patients, a consensus was reached on follow-up imaging results: pNET (n = 1), serous cystadenoma (n = 2) and undetermined/no pNET (n = 2). Both specificity and negative predictive value of ¹⁸ F-FDOPA PET/CT for localized pNET were 67%. Surprisingly, all four false-positive results were SPTs showing intense ¹⁸ F-FDOPA uptake and negative SRS. There was no significant difference in ¹⁸ F-FDOPA uptake intensity between PET-positive pNETs and SPTs.

CONCLUSION

¹⁸ F-FDOPA PET/CT is not specific for pNET in patients with localized pancreatic lesions. SPT could mimic pNET and should be part of differential diagnosis in such a clinical situation. If these results are confirmed in a broader population, the imaging pattern ¹⁸ F-FDOPA PET-positive/SRS-negative lesions might be considered as the imaging phenotype of SPT.

Solid pseudopapillary neoplasm of the pancreas: a report of 10 cases and literature review

BACKGROUND

Solid pseudopapillary tumour of the pancreas (SPTP) is a rare pancreatic tumour characterized by a non-specific clinical presentations and vague radiologic features. The aim of this study is to identify these tumours from other pancreatic neoplasms because complete resection is curative in most cases and provides long-term survival.

METHODS

A retrospective analysis of patients operated for SPTP between January 2000 and December 2018 was conducted. The collected data included age, gender, clinical findings, laboratory tests, radiological findings, anatomopathological examination, immunohistochemistry results, surgical treatment, mortality, morbidity and recurrence.

RESULTS

Ten cases of SPTP have been diagnosed between January 2000 and December 2018 representing 5.1% of all pancreatic tumours operated during this period (male/female: 2/8; median age 41.2 years; range 19-78 years). The most common symptom was abdominal pain and physical examination was normal in four of 10 cases. The most common tumour localization was the tail of the pancreas. The main tumour size was 7.2 cm (range 2-15 cm). One patient had abdominal disseminated disease. Surgical interventions were distal pancreatectomy in five cases, enucleation in one case, cephalic duodeno-pancreatectomy in two cases, central pancreatectomy in one case and pancreatic biopsy in one case. Only one patient received adjuvant chemotherapy. During follow-up, one patient died after 12 months and another developed unique hepatic metastasis that was resected.

CONCLUSION

Although it is delayed in diagnosis, the overall prognosis of these tumours remains good even with local recurrence and metastasis. Complete surgical resection is the treatment of choice even in cases of recurrence.

Distal Pancreas and Spleen-preserving Central Pancreatectomy in a Locally Aggressive Solid Pseudopapillary Neoplasm of Pancreas: A Novel Extended Warshaw Technique

Central pancreatectomy (CP) is a well-described procedure done for neck and proximal body tumors of the pancreas. It can be done for benign lesions where an adequate length of normal distal pancreas will be left leading to organ preservation. The currently described benefit of the procedure is decreased long-term morbidity due to retention of both the spleen and the preservation of functioning pancreas. This is usually dependent on the preservation of distal pancreatic vascularity by splenic artery preservation. Many studies have described splenic preservation by Warshaw technique by safeguarding the short gastric (SGA) and left gastroepiploic (LGEA) vessels in case of distal pancreatectomy. However, distal pancreatic preservation during CP with splenic vessels ligation is not given a significant mention in the current literature in relation to Warshaw technique. Here, we present a 19-year-old girl diagnosed with an exophytic solid pseudopapillary tumor of the pancreatic body that was selected for central pancreatectomy. In view of splenic vessels involvement, she underwent ligation of the splenic vessels and splenic preservation was based on the LGEA and SGA. Distal pancreas was anastomosed with a roux en loop of jejunum and intra-operatively, we were able to demonstrate the back flow in the splenic vessels. Postoperative computed tomography showed adequate enhancement of the spleen along with retrograde blood flow into the distal splenic artery with enhancement of the distal pancreas. Her postoperative period went uneventful. Thus CP with extended Warshaw technique is a safe and feasible procedure where indicated.

[Solid pseudopapillary tumour of the pancreas: about a case and review of the literature]

Solid pseudopapillary tumours of the pancreas are rare tumours of uncertain etiology which mostly affects young women. Their prognosis is good especially after complete resection. We report a new case of a young woman; abdominal pain revealed solid pseudopapillary tumour. The diagnosis is based on histological examination associated with immunohistochemistry of the piece of resection removed with caudal splenopancreatectomy.

Beger procedure in a 20-year-old female with solid pseudopapillary tumour of the pancreas

Solid pseudopapillary tumour is a rare indolent neoplasm of the pancreas (< 2% of exocrine pancreatic tumours), which predominantly affects young women at reproductive age, without significant clinical symptoms.

We report a case of a 20-year-old Caucasian female who presented with upper abdominal pain of one-year duration. Ultrasound scans of the abdomen demonstrated enlarged pancreatic head and body containing a poorly separated mass (52 × 41 × 36 mm) with a multi-cystic component 20–24 mm in diameter. Laboratory tests including, tumour markers levels, were normal. She underwent complete resection of the tumour using a Beger procedure. By immunohistochemistry, the case stained strongly for CD10 and CD56 and was negative for cytokeratin-7 (CK-7), synaptophysin and chromogranin A. The proliferation index (Ki-67) was < 1%. The patient is being followed-up and remains healthy.

Pancreatic tumours: molecular pathways implicated in ductal cancer are involved in ampullary but not in exocrine nonductal or endocrine tumorigenesis

Alterations of K- ras, p53, p16 and DPC4/Smad4 characterize pancreatic ductal cancer (PDC). Reports of inactivation of these latter two genes in pancreatic endocrine tumours (PET) suggest that common molecular pathways are involved in the tumorigenesis of pancreatic exocrine and endocrine epithelia. We characterized 112 primary pancreatic tumours for alterations in p16 and DPC4 and immunohistochemical expression of DPC4. The cases included 34 PDC, 10 intraductal papillary-mucinous tumours (IPMT), 6 acinar carcinomas (PAC), 5 solid-pseudopapillary tumours (SPT), 16 ampulla of Vater cancers (AVC) and 41 PET. All tumours were also presently or previously analysed for K- ras and p53 mutations and allelic loss at 9p, 17p and 18q. Alterations in K- ras, p53, p16 and DPC4 were found in 82%, 53%, 38% and 9% of PDC, respectively and in 47%, 60%, 25% and 6% of AVC. Alterations in these genes were virtually absent in PET, PAC or SPT, while in IPMT only K- ras mutations were present (30%). Positive immunostaining confirmed the absence of DPC4 alterations in all IPMT, SPT, PAC and PET, while 47% of PDC and 38% of AVC were immunonegative. These data suggest that pancreatic exocrine and endocrine tumourigenesis involves different genetic targets and that among exocrine pancreatic neoplasms, only ductal and ampullary cancers share common molecular events.