Endoscopic Ultrasound-Guided Fine Needle Aspiration of Solid Pseudopapillary Neoplasm of the Pancreas in a Male Patient: A Rare Report

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Abstract Introduction/Objective Solid pseudopapillary neoplasm (SPN) of the pancreas is a rare pancreatic tumor with low malignant potential composed of poorly cohesive epithelial cells forming solid and pseudopapillary structures. It develops almost exclusively (90%) in young females (mean age: 28 years, range: 7-79 years), while it rarely develops in men (mean age: 35 years, range: 25-72 years). Methods/Case Report Herein we report an unusual presentation of SPN in a 59-year-old male who presented with severe nausea, vomiting, right upper quadrant pain, and weight loss. Computed tomography imaging revealed a large pancreatic head/uncinate process mass. Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) biopsies showed abundant monomorphic cuboidal tumor cells arranged in loosely cohesive groups and singly dispersed cells. A few tumor cells are arranged in multiple layers around vascular structures expanded by metachromatic hyaline material. The tumor cells have thin cytoplasm, indistinct cell borders, round to oval nuclei, finely dispersed chromatin, and indistinct nucleoli. No mitosis, tumor necrosis, or other high-grade features are identified. Immunohistochemical stains are performed on cell block material and the tumor cells are positive for beta-catenin (nuclear), cyclin D1, vimentin, CD10, synaptophysin, and CD56, and negative for DOG-1, tryptase, and AE1/AE3. Ki-67 proliferative index is less than 2% in tumor cells. The cytomorphologic features and immunoreactivity are diagnostic of solid pseudopapillary neoplasm. We diagnosed SPN preoperatively by EUS-FNA using cytopathologic and immunochemical characteristics, which are very helpful to differentiate SPN from acinar cell carcinoma, neuroendocrine tumor, pancreatoblastoma, or other pancreatic tumors. Results (if a Case Study enter NA) NA Conclusion EUS-FNA can be used as a gold standard method to characterize and diagnose SPN preoperatively and help to guide clinical management.