A rare case of pancreatic schwannoma diagnosed preoperatively by endoscopic ultrasound-guided fine needle biopsy, the role of contrast-enhanced US and US elastography. There are no disclosures of authors. Endoscopic ultrasound fine needle aspiration biopsy is the method of choice for the evaluation of focal pancreatic masses. Multiparametric US is used for the real-time guidance of USFNA or USFNB. A combination of grayscale imaging, color Doppler, US elastography, and contrast-enhanced US is used. US elastography is performed in real time and it shows the relative tissue strain based on combined autocorrelation method. It works in real time and it shows the elastography information overimposed on the grayscale information. So in the right side image, you can see the elastography information inside the focal pancreatic mass, which is low strain as compared to the surrounding pancreatic parenchyma. Strain histograms can be used for quantification. Contrast-enhanced US is used for the clear visualization of non-necrotic areas and major interposed vessels. The wideband pulse inversion method is used to enhance the signal from the contrast agent. Specifically, microbubble contrast agents are used, which are staying in the vessels. They are blood pool ultrasound contrast agents. So basically, this is how the image looks like with the microvasculature and the macrovasculature clearly visible, depicting the signals inside the tumor and the major vessels surrounding it. We present a 54-year-old patient, which was evaluated for an enlarged retroperitoneal leaf node depicted on cross-sectional imaging, namely contrast-enhanced CT. And this is how the grayscale looked like and also the color Doppler US. So basically, a 3.4 times 1.8 centimeter hypoechoic lesion was visualized, encapsulated with slight heterogeneous content located on the posterior side of the pancreas in close proximity of the pancreatic head, superior mesenteric vein, and artery. US allostrography showed that heterogeneous low-strain, hard, non-compressible focal pancreatic mass visualized relatively to the normal pancreatic parenchyma. Contrast-enhanced US showed a heterogeneous arterial hyper-enhancement, followed by washout in the venous phase. So basically, the tumor was hyper-enhanced, but it was washing out. So the contrast enhancement was less inside the tumor as compared to the surrounding pancreatic parenchyma. US-guided fine-yield biopsy was further performed, showing decreased acinar pancreatic tissue with fragments of spindle cells, a positive S100 and SOX10, negative cytokeratin AA1, AA3, DOG1, and synaptophysin, and a K67 proliferation index of less than 5%. Pancreatic schwannoma is a rare tumor. Over 100 cases are described in the literature. It is the most common peripheral nerve tumor, although it is benign. It can have malignant potential, especially if it is large. Furthermore, tumors are variable in size and they might undergo degenerative changes characterized by cis-formation, calcification, hemorrhage, hyalinization, as well as xanthomatous infiltration. Imaging diagnosis by cross-sectional methods, computer tomography, and or magnetic resonance imaging are thus nonspecific, showing a low attenuation lesion on CT with a clearly defined capsule on MR. The diagnosis in our case was confirmed by US-guided FNB, followed by pathology exam. Although the diagnosis confirmed a benign schwannoma, the decision after a multidisciplinary meeting was to further refer the patient for surgical excision and nucleation of the mass in view of the malignancy risk. So in conclusion, US allostrography and contrast-enhanced US are useful methods to guide US final biopsy for confirmation of the diagnosis of schwannoma. Pathology diagnosis is essential in these rare pancreatic tumors to decide on the risk of malignancy. An informed, evidence-based decision for the management of this patient should be reached in the multidisciplinary tumor board, including also the patient opinion.

pancreatic schwannoma

contrast-enhanced US

US elastography

endoscopic ultrasound

fine needle aspiration biopsy