Solid pseudopapillary tumor of the pancreas suggesting malignant potential

Objectives: It has been suggested that the histopathologic features associated with malignant potential in solid pseudopapillary tumors (SPTs) of the pancreas include cellular polymorphism, mitotic activity, peripancreatic tissue invasion, neural invasion, lympbovascular invasion, and lymph node metastasis. This study aimed to delineate the features predicting SPTs with malignant potential, which can be easily assessed in the clinical setting, and long-term results of patients who underwent resection of SPT. Methods: A retrospective review and analysis were done of 33 patients who had SPTs that were surgically treated. Results: Eleven patients (33.3%) had SPTs suggesting malignant potential among surgically treated patients with SPTs. The local invasion to the peripancreatic tissue was the most frequent malignant pathological feature (7/11 patients, 63.7%). Using univariate analysis, tumor size greater than 5 cm was a significant clinical factor to predict SPTs with malignant potential (P = 0.022). The prognosis was excellent. No statistically significant survival difference was noted between groups of malignant potential and benign pathology (P = 0.1904). Conclusions: Malignant SPTs are low-grade tumors with good prognosis. Adequate surgical intervention is necessary. Especially, SPTs over 5 cm in diameter need to be treated carefully because of the chance of malignant pathology. Careful long-term follow-up is necessary in those patients in case of possible tumor recurrences.