Solid pseudopapillary neoplasms of the pancreas: clinicopathological and radiological features according to size, twenty-year experience from a high-volume center

Purpose: To analyze and correlate clinicopathological and radiological features of resected solid pseudopapillary neoplasms of the pancreas according to their size. Material and methods: Clinicopathological and radiological features of resected solid pseudopapillary neoplasms (SPN) of the pancreas over a twenty-year period were retrospectively analyzed. For the purpose of statistical analysis, tumors were divided into three groups according to their size (≤30 mm, 31-50 mm, and >50 mm). Clinicopathological and radiological features were compared among groups using Kruskal-Wallis’ and Fisher’s exact tests. Results: Between January 1997 and December 2017, the study population consisted of 106 patients, with a median age at diagnosis of 31 years (range 7–68). Patients with small tumors (≤30 mm) had a significantly higher age at diagnosis compared with the other groups of patients (p=.038). Large tumors (31-50 and >51 mm) were more frequently located in the pancreatic body/ tail compared with tumors ≤30 mm (p=.008). No other significant differences were found between the clinicopathological features of the three groups of patients (all p>.05). Most tumors presented a mixed solid and cystic appearance (54.7%), with well-defined margins (87.7%). Tumors ≤30 mm were significantly more frequently entirely solid (53.8%) compared with larger tumors (p=.028). The rate of incorrect preoperative diagnosis was higher in tumors ≤30 mm compared with larger tumors, albeit without significant differences between groups (p=.561). Conclusion: Malignancy in solid pseudopapillary neoplasms is not correlated with tumor size; tumors ≤30 mm may present atypical imaging features, which may overlap with those of other solid tumors of the pancreas.