A0070 - A Rare Incidence of Pancreatic Schwannoma

Kyaw Min Tun, DO¹, Yassin Naga, MD¹, Blaine Massey, DO¹, Zahra Dossaji, DO¹, Salman Mohammed, BS¹, Sami Mesgun, BS¹, Osman Rahimi, DO¹, Gopi Narra, DO¹, Katrina Naik, MD¹, Amith Subhash, MD¹, Annie Hong, MD¹, Jill Ono, MD², Jose Aponte-Pieras, MD¹, Shahid Wahid, MD¹, Gordon Ohning, MD, PhD^1
1Kirk Kerkorian School of Medicine at UNLV, Las Vegas, NV; ²University Medical Center of Southern Nevada, Las Vegas, NV

Introduction: Schwannomas are benign, slow-growing tumors that originate from Schwann cells. About 90% of schwannomas are sporadic, while the remaining 10% are associated with genetic disorders such as neurofibromatosis type 2. The majority of schwannomas occur in the head, neck, and distal extremities. Pancreatic schwannomas are exceptionally rare, with less than 70 reported cases in the literature in the past 30 years.

Case Description/Methods: A 64-year-old male with a history of intra-abdominal fibrosarcoma presented with acute encephalopathy from amphetamine use which resolved with supportive care. Patient was previously told that the fibrosarcoma was unresectable. He reported completing chemotherapy in 1991 and did not receive further treatment. Previous medical records were unavailable. A computerized tomography (CT) imaging of the abdomen revealed a 6.5x6.8x9.3 cm mass along the head of the pancreas with peripheral calcifications. Bilateral enlargement of inguinal, iliac, and retroperitoneal lymph nodes was also noted. Endoscopic ultrasound demonstrated a large heterogeneous and hypoechoic pancreatic head mass with septations and calcifications. Specimens attained with fine needle aspiration revealed numerous aggregates of spindle-shaped cells without tumor cell necrosis or mitotic figures. Immunohistochemical stains were positive for S100 and SOX-10, suggestive of a peripheral nerve sheath tumor; pankeratin staining was weakly positive. Immunostains such as smooth muscle actin, CD117, CD34, desmin, DOG-1, HMB-45, and Melan A were negative which excluded sarcoma, gastrointestinal stromal tumor (GIST), and melanoma. A diagnosis of pancreatic head schwannoma was made. Biopsy of the right inguinal lymph node was unremarkable for neoplasm. Due to the schwannoma encasing the superior mesenteric artery and vein, the patient was not a surgical candidate and was discharged for outpatient monitoring.

Discussion: Pancreatic schwannomas are an extremely rare clinical entity. Patients may display non-specific symptoms or remain asymptomatic. CT imaging commonly shows encapsulated, heterogeneous, and hypodense lesions as seen in our patient. S100 immunostaining is crucial for confirming the diagnosis. A specimen positive for S100 but negative for CD34, DOG-1, and HMB-45 as above is subtyped as a pancreatic schwannoma with ancient features. Conservative management is recommended; symptomatic patients may benefit from surgical resection.



Disclosures:


Kyaw Min Tun, DO¹, Yassin Naga, MD¹, Blaine Massey, DO¹, Zahra Dossaji, DO¹, Salman Mohammed, BS¹, Sami Mesgun, BS¹, Osman Rahimi, DO¹, Gopi Narra, DO¹, Katrina Naik, MD¹, Amith Subhash, MD¹, Annie Hong, MD¹, Jill Ono, MD², Jose Aponte-Pieras, MD¹, Shahid Wahid, MD¹, Gordon Ohning, MD, PhD¹. A0070 - A Rare Incidence of Pancreatic Schwannoma, ACG 2022 Annual Scientific Meeting Abstracts. Charlotte, NC: American College of Gastroenterology.