Pancreatic Schwannoma: A rare case in the setting of Diffuse B-cell Lymphoma and Follicular Lymphoma

Schwannomas are typically benign tumors arising from schwann cells of cranial nerves, spinal nerve roots, or peripheral nerves. Schwann cells, which produce myelin, are a major cell type in the peripheral nervous system, performing critical roles in axonal maintenance, function, and regeneration of peripheral nerves.¹ Although schwannomas have been reported in a multitude of locations including the head, neck, extremities, mediastinum, and retroperitoneum, pancreatic schwannomas (PS) are rare with only around 50 case reports.² In 2004, Paranjape et. al., presented a review of 39 PS cases and found an average age of 57.75 years, median size 8.79 cm and most commonly (40%) located in the pancreatic head. 36.7% were described as solid and 47.6% were described as cystic.³ Presenting symptoms of patients with PS include abdominal pain, nausea, vomiting, weight loss, and jaundice. Most PS are slow growing and encapsulated, with well defined margins. In cytological exam, schwannomas are spindle shaped cells with vague cytoplasmic boundaries embedded in a fibrillar wavy nucleus. S100 immunochemical stain is seen in PS, although not specific to schwannomas.⁴ The differential for PS includes pancreatic cystic neoplasms, neuroendocrine tumors, pancreatic pseudocyst, intraductal papillary mucinous neoplasm, cystadenocarcinoma, and lymphoma. Pancreatic schwannomas can be incidental on computed tomography (CT) but require tissue for diagnosis via endoscopic ultrasound (EUS), guided fine needle aspiration (FNA), or biopsy. Although the risk for malignant PS is small, benign PS can cause complications due to their size, thus surgical resection is recommended. Surgical approaches vary and range from enucleation to pancreaticojejunostomy