Solid pseudopapillary neoplasm of pancreas

Abstract Rationale: About 8384 cases of solid pseudopapillary neoplasms (SPN) of pancreas have been published in English literature, from 1933 to 2018. This is a low-grade tumor that usually occurs in children but is rare in adults and, in exceptional cases, can show extrapancreatic localization. In this paper we present 2 unusual cases of SPNs, 1 with retroperitoneal location (case 1) and 1 that was firstly diagnosed as a G1 neuroendocrine tumor (NET) and showed hepatic metastases after 13 years (case 2). Patient concerns: No symptoms in first case. The tumor was incidentally diagnosed, during ultrasound examination. In the second case, the metastasis was observed during regular follow-up. Diagnoses: The diagnosis was established based on the histological features and immunohistochemical profile that showed positivity for vimentin, nuclear β-catenin, cyclin D1, CD10, and SRY-related high-mobility group box 11 and negativity for maspin. Interventions: Surgical excision, in both cases. Outcomes: No recurrences in first case, at 5 months after diagnosis. Hepatic metastases in the second case, at 13 years after diagnosis, with portal invasion after another 15 months. Lessons: Without a complex immunoprofile, SPN can be misdiagnosed as NET. SPN can be a low-grade tumor but long-time follow-up is mandatory to detect delayed metastases. A correct diagnosis is necessary for a proper therapeutic management.