Abstract
Background: Studies investigating prognostic factors of solid pseudopapillary neoplasm (SPN) have been published with conflicting findings.Methods: Retrospective analysis of 63 consecutive cases of SPN in our institution from January 2010 to December 2019 was carried out. The clinicopathological features, treatment practices along with survival associations were collected and analyzed.Results: Fifteen patients (23.8%) were male, and 48 (76.2%) were female, with a median age of 34.0 ± 14.5 years. The larger tumor size was correlated with the more mixed components (p = 0.000) and the higher Ki-67 index (p = 0.042). No recurrence was found in the nine patients whose tumors fulfilled the WHO criteria for malignancy due to the presence of at least perineural invasion (6.4%), angiovascular invasion (2.3%), and/or adjacent organ invasion (6.4%). Microscopic infiltrative growth was detected in 9 (14.3%) tumors, which was correlated significantly with the WHO criteria (p = 0.002), capsule invasion (p = 0.005), and pancreatic parenchyma invasion (p = 0.001), but not with disease-free survival (p = 0.13). CD99 was found to be positively expressed in 88.9% (40/45) of tumors and more likely to have depressed Ki-67 index (p = 0.016). After a median follow-up of 58 months, only two patients (3.2%) had a recurrence after their first operation outside of our hospital. No patient died due to tumor progression.Conclusions: Although survival is favorable with aggressive surgery, it is actually difficult to assess the prognostic factors of resected SPNs. Future investigations into the role of clinicopathological evaluation will unveil the prognostic enigma of pancreatic SPN after resection.
Highlights
Solid pseudopapillary neoplasm (SPN) is a rare pancreatic tumor, which was first defined by Frantz in 1959 and classified as a potential malignant neoplasm by WHO in 2010 [1]
It can be clearly found that the diagnosis of SPNs has progressively increased over 10 years in our institution, which is in line with the reported significant increase in the incidence of SPN in the past decade
Solid features were found in 26 patients (41.3%), and cystic features were found in two patients (3.2%)
Summary
Solid pseudopapillary neoplasm (SPN) is a rare pancreatic tumor, which was first defined by Frantz in 1959 and classified as a potential malignant neoplasm by WHO in 2010 [1]. The biologic behaviors of SPN are mostly less aggressive in spite of the tumor phenotype and classically present as large, solitary, wellcircumscribed lesions with female predominance [2]. One of the biggest challenges in managing patients with SPN lies in predicting tumor behavior at the time of presentation [4]. The WHO criteria of malignancy, which focused on microscopic features of malignancy, cannot be always equated with predicting the clinical malignant prognosis of SPN, nor were immunohistochemical stains, including the proliferative index Ki67 [5, 6]. Studies investigating prognostic factors of solid pseudopapillary neoplasm (SPN) have been published with conflicting findings
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