A Rare Case of Pancreatic Schwannoma as a Cause of Chronic Abdominal Pain: A Management Dilemma

Introduction: Pancreatic schwannomas are exceedingly rare and can be easily misdiagnosed due to their tendency to mimic other pancreatic lesions, leading to unnecessary interventions. Accurate preoperative diagnosis is essential to guide appropriate management and optimize patient outcomes. We report a case of chronic abdominal pain secondary to pancreatic schwannoma with infiltrative/aggressive behavior. Case Description/Methods: A 59-year-old male with past medical history of meningioma status post craniotomy and a previous episode of pancreatitis presented with complaints of chronic abdominal pain, nausea, vomiting and unintentional weight loss of 15 pounds over the past year. Laboratory findings were unrevealing. Computed tomography (CT) imaging of the abdomen showed a mass at the uncinate pancreas measuring 2.1 x 2.4 cm. Subsequent magnetic resonance imaging (MRI) demonstrated a non-specific 2.8 cm tumor abutting the superior mesenteric artery without perivascular extension. On EUS examination, the mass was hypoechoic and heterogeneous, measuring 2.9 x 2.6 cm and appeared solid with a central cystic area. Fine needle biopsies revealed spindle cell proliferation positive for S100 and SOX-10 staining, more consistent with schwannoma. The patient’s pain was unsuccessfully managed with pain medications, including intravenous opioid therapy. Celiac plexus neurolysis was discussed; however, given the location of tumor, surgery team recommended surgery evaluation for resection (Figure 1). During surgery, it was not possible to dissect the tumor away from the superior mesenteric artery. Extensive omental and intestinal adhesions also hindered a successful Whipple reconstruction. Therefore, alcohol ablation of the tumor was performed and fiducial markers were placed for adjuvant radiation therapy. Patient had good success of pain relief post-procedure. He was discharged for follow-up with surgical oncology and radiation oncology. Discussion: Pancreatic schwannoma is extremely rare and comprises less than 1% of all schwannomas. While schwannomas are generally considered benign and slow-growing lesions, the presentation of the tumor in this patient resembles malignant behavior given its expansion to vital structures, including local blood vessels. We report this unusual presentation of a pancreatic schwannoma with the use of alcohol ablation for successful pain management. Further studies are needed on the safety and efficacy of alcohol ablation in the management of symptomatic pancreatic schwannomas.Figure 1.: A) EUS: solid hypoechoic and heterogeneous mass with a central cystic area measuring 2.9 x 2.6 cm, B) H&E staining revealed spindle cell proliferation and focal palisading of the nuclei consistent with schwannoma, C) IHC stain revealing positivity for s-100.