Introduction
Pancreatic schwannomas (PS) are an extraordinarily rare form of pancreatic tumors, with fewer than 100 reported cases globally[
1]. These tumors arise from Schwann cells within the neural sheath and are typically benign, demonstrating slow growth. The head of the pancreas is most commonly involved, with approximately 40% of cases occurring in this region. While pancreatic schwannomas are generally non-cancerous, malignant transformation is possible, particularly in larger tumors or in individuals with conditions like neurofibromatosis type 1 disease. Degenerative changes, such as cystic development, calcification, and hemorrhage, are seen in about two-thirds of cases, highlighting the varied histopathological features of these tumors. Due to their potential for diverse clinical presentations, imaging findings, and histological patterns, an accurate preoperative diagnosis is challenging. Surgical resection remains the primary treatment, offering a curative solution for most patients affected by this rare pancreatic neoplasm.
Case presentation
A 64-year-old female presented with complains of abdominal pain for 2 years, on Contrast-Enhanced Computed Tomography (CECT), a peripherally enhancing cystic lesion with internal septae within epicentered in head of pancreas measuring 8.8 cm × 8.5 cm with few foci of calcification with no communication to main pancreatic duct (Figure 1A, 1B). No obvious solid component seen. Serum Carcinoembryonic Antigen (CEA) and CA-19.9 measured 1.94 ng/mL and 9.11 U/mL respectively.
Endoscopic Ultrasound (EUS) was performed for the patient which showed an anechoic multiloculated lesion in head of pancreas, however patient developed fever spikes after the procedure and a repeat CECT along with Ultrasonography (USG) was performed for the patient which showed air foci within the cystic lesion (Figure 2A, 2B). Pigtailing of cystic lesion was performed in suspicion of an infected pseudocyst under antibiotic cover. Aspirated purulent material showed an amylase and CEA levels of 6 U/L and 204.52 ng/mL, isolated with Klebsiella oxytoca as pathologic organism. Enucleation surgery was performed on the patient, histopathology showed benign peripheral nerve sheath tumor with additional S100 positivity confirming diagnosis of schwannoma.
Currently the patient is doing well and kept on regular follow-up.
Discussion
Schwannomas are benign tumors composed of spindle cells derived from Schwann cells in nerve sheaths. Although they can arise in various locations, such as the lower extremities, trunk, and mediastinum, PS are exceedingly rare, making up less than 1% of all schwannomas. Notably, two-thirds of these tumors exhibit cystic features.
PS primarily originate from autonomic nerve fibers or the vagus nerve. They are most commonly located in the head of the pancreas (40%), followed by the corpus (21%), tail (15%), neck (6%), and uncinate process (13%)[
2]. These tumors often undergo degenerative changes, including cyst formation, hemorrhage, and calcification, which can mimic other pancreatic conditions such as cystic neoplasms, neuroendocrine tumors, or pseudocysts.
While generally benign, larger tumors or those with increased mitotic activity and genetic mutations (e.g., Ki-67, p53, Bcl-2)[
3,
4] may have a higher risk of malignant transformation. Symptoms can vary widely, with abdominal pain being the most common like presentation with our case, though many patients remain asymptomatic. Other potential symptoms include weight loss, nausea, jaundice, and back pain, though there is no clear correlation between these symptoms and tumor size or location.
This case represents a rare instance of a cystic PS complicated by post-EUS infection with Klebsiella oxytoca, initially masquerading as an infected pseudocyst. The elevated cystic fluid CEA levels, along with imaging findings mimicking cystic neoplasm, add to the diagnostic challenge. To our knowledge, this is among the very few reported cases — and possibly the first — of an infected pancreatic schwannoma presenting in this manner.
Pancreatic pseudocyst is common and can be indistinguishable from PS on initial imaging. However, our patient lacked a history of severe acute or chronic pancreatitis. The development of secondary infection and air foci (Figure 2A, 2B) led to an initial misdiagnosis of an infected pseudocyst, highlighting the diagnostic overlap and the utility of histopathology to correct the diagnosis. Mucinous Cystic Neoplasm (MCN) are typically macrocystic, located in the body/tail, and occur predominantly in women, similar to our patient’s gender and macrocystic appearance. However, the peripherally enhancing wall/septae on CECT is less specific for them compared to PS. More critically, MCNs often require radical resection (distal pancreatectomy), whereas our final PS diagnosis allowed for the less invasive enucleation, emphasizing the importance of accurate final diagnosis. Serous Cystadenoma (SCAs) typically present as a microcystic or “honeycomb” mass, which contrasts with our macrocystic and septated lesion.
Immunohistochemical staining for S-100 protein is crucial for confirming the diagnosis, and normal levels of CA 19-9 and CEA help exclude pancreatic adenocarcinoma. Enucleation is the preferred treatment due to the typically encapsulated and benign nature of these tumors. In cases of suspected malignancy, surgical options may include the Whipple procedure or distal pancreatectomy.
Conclusion
Pancreatic schwannomas are extremely rare and despite the availability of various imaging techniques, achieving an accurate preoperative diagnosis remains a significant challenge. Surgery is the primary treatment for PS, and the approach varies depending on the tumor’s location within the pancreas. Recently, there has been a growing trend of accurate preoperative diagnoses through endoscopic ultrasound-guided fine needle aspiration (EUS-FNA), and careful surveillance has also emerged as a viable management option. Following surgical resection, patients with PS generally experience a favorable prognosis.
The Author(s) 2026. This article is published with open access at journal.hep.com.cn.
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