Solid pseudopapillary neoplasm of the pancreas: clinicopathologic and survival analyses of 64 cases from a single institution

Although solid pseudopapillary neoplasms (SPNs) are considered tumors of low malignant potential, patients may present with aggressive disease (ie, liver metastasis/invasion into adjacent organs) and, rarely, die from disease. Although the clinicopathologic features associated with aggressive SPNs have been reported, important prognostic factors of survival remain unclear. We systematically reviewed 64 cases of SPN resected at our institution for tumor size, extent of invasion, margin status, presence of lymphovascular, muscular vessel, and perineural invasion, and lymph node and distant metastases. Clinicopathologic characteristics were correlated with the presence of metastasis/recurrence and disease-specific survival. Five (8%) patients presented with stage IV disease. During follow-up, 5 (13%) of 39 patients with stage I-II disease had recurrences. Patients with metastatic/recurrent SPNs had significantly larger tumor size (P<0.001) and more frequent tumor invasion into muscular vessels (P=0.02). In a median follow-up of 76 months, only 2 died of disease (1 who presented with extensive peritoneal tumor involvement who died 2.5 mo after surgery, and 1 unusual case who presented with multiple liver metastasis and peritoneal seeding who died 19 mo after surgery), and 5 were alive with disease. The 10-year disease-specific survival rate was 96%. Muscular vessel invasion (P=0.001), tumor (T) stage by European Neuroendocrine Tumors Society (ENETS) classification (P<0.001), ENETS stage grouping (P<0.001), and stage grouping by the American Joint Committee on Cancer (AJCC stage, P<0.001) were important predictors of disease-specific survival in patients with SPN. Our study highlights the importance of pathologic evaluation in risk assessment in patients with SPNs.