Pancreatic Neuroendocrine Neoplasms and Gastrointestinal Stromal Tumors: A Single-Institution Experience of a Rare Association and Review of the Literature.

Pancreatic neuroendocrine neoplasms (pNENs) and gastrointestinal stromal tumors (GISTs) represent rare neoplasms. Nonsyndromic cases of pNENs associated with a synchronous GIST were evaluated, and a review of the literature was performed. We evaluated clinicopathologic features, postoperative outcome, and follow-up of patients operated on for nonsyndromic synchronous pNENs and GISTs in our unit (2003-2017). Five (3.2%) of 156 patients with a pNEN had an associated GIST (3 male/2 female; average age, 67 years). They were diagnosed with a pNEN preoperatively and underwent pancreatic surgery. In 4 patients, GISTs were detected intraoperatively. Histology showed 3 G1 and 2 G2 pNENs. All GISTs were low risk (median size, 0.9 cm). Two patients were alive without disease 108 and 132 months after surgery. In the literature, 7 cases were described. They had low-risk GISTs, with a gastric location in 6 cases (median size, 2.85 cm). Sporadic pNENs coexisting with a GIST have been demonstrated in 12 cases. This association is considered fortuitous, and its true incidence may be underestimated. Surgery should be performed on the GIST during the pancreatic surgery. The prognosis strictly depends on the pancreatic NENs.