Solid Pseudopapillary Neoplasm of the Pancreas Mimicking Low Grade Neuroendocrine Tumor

Abstract

Introduction: Solid pseudopapillary neoplasms (SPN) and pancreatic neuroendocrine tumors (NET) are rare diseases that are generally incidental findings in imaging tests. SPN is a low-grade tumor with good prognosis that more commonly affects young female patients. Pancreatic NET has a significant variability in outcomes, with low malignant potential in non-progressing tumors that are welldifferentiated. Both tumors may appear very similar in imaging tests and immunohistochemical (IHC) evaluation, which makes the differential diagnosis challenging, especially in small lesions. Case report: The authors present the case of a 34-year-old male with a medical history of a primary mediastinal germ cell tumor. The patient had no symptoms. Follow-up abdominal CT scan evidenced a single, well-delimited nodular lesion in the pancreatic neck, measuring 17mm in diameter. The patient was submitted to an endoscopic ultrasound-guided fine needle aspiration biopsy (EUS-FNA) and after IHC analysis, there was a diagnostic suspicion of low-grade pancreatic NET. Central pancreatectomy (CP) was performed and complete lesion analysis evidenced a pancreatic SPN. Conclusion: The SPN can mimic low-grade nonfunctioning pancreatic NETs in imaging tests and EUSFNA IHC evaluation.