The parapharyngeal space is a pyramid-shaped space located between the base of the skull and the hyoid bone, lateral to the naso-oropharynx and medial to the jaw [1]
[2]. It contains the deep lobe of the parotid gland, cranial nerves IX – XII, the internal jugular vein, and the carotid artery [1]. A variety of benign and malignant tumors arise in the parapharyngeal space, the most common being of salivary gland and neurogenic origin [1]. Because of its deep location and concerns about damaging adjacent structures, the parapharyngeal space is difficult to access for biopsy [1]
[2]
[3]. Percutaneous, transoral, or transnasal approaches have been used; however, sampling may be challenging even under imaging guidance [2]
[3]
[4]
[5]. Here we report for the first time a technique of transoral biopsy using a flexible gastrointestinal echoendoscope.
A 41-year-old man with a remote history of mucoepidermoid carcinoma of the left parotid gland presented with a tumor of the right parapharyngeal space ([Fig. 1]). A multidisciplinary tumor board recommended biopsy; however, this was deemed difficult due to the tumor location. After discussion with a gastroenterologist experienced in endoscopic ultrasound (EUS), a decision was made for biopsy under EUS guidance.
Fig. 1 Magnetic resonance images showing a tumor (TU) of the right parapharyngeal space. a Unenhanced T1-weighted coronal image. The tumor is located between the wall of the nasopharynx, lateral (lpm) and medial pterygoid muscles (mpm), and ramus of the mandible. It is 34 mm × 25 mm in size, has well-delineated borders, and a homogeneous low-intensity T1 signal. b Gadolinium-enhanced transverse image. The tumor has an inhomogeneous enhancement pattern. A connection to the deep lobe of the right parotid gland is visible (asterisk).
With the patient in the left lateral position and under intravenous sedation, a flexible echoendoscope (Olympus GF-UCT180) was introduced in a standard manner into the oral cavity and torqued clockwise. After passing the palatopharyngeal fold, the EUS transducer was gently wedged against the right lateral wall of the pharynx ([Fig. 2]). In this position the tumor was easily identified on the EUS image. Three passes with a 22-gauge Acquire needle (Boston Scientific) were performed ([Fig. 3], [Video 1]). The specimen was processed for histological evaluation, which revealed pleomorphic adenoma ([Fig. 4]). The patient was discharged 48 h later after an uneventful course. The tumor was resected 4 weeks later. Surgical pathology confirmed the diagnosis of pleomorphic adenoma of the deep lobe of the right parotid gland.
Fig. 2 Schematic drawing of the anatomy of the mouth and throat (midsagittal plane), showing the position of the echoendoscope during endoscopic ultrasound (EUS) examination and fine-needle biopsy of the tumor.
Fig. 3 EUS image of a tumor of the right parapharyngeal space located between the pharyngeal wall, the medial pterygoid muscle (mpm), and the ramus of the mandible. The tumor (TU) is 34 mm × 28 mm in size, has well-delineated borders and a hypoechoic, homogeneous echo pattern. A needle passing through the pharyngeal wall into the tumor is visible.
Video 1 Successful transoral endoscopic ultrasound-guided biopsy of a tumor of the parapharyngeal space (pleomorphic adenoma of the deep lobe of the parotid gland).
Fig. 4 Specimen obtained by EUS-guided fine-needle biopsy under 100 × magnification. Typical appearance of a pleomorphic adenoma of the parotid gland with epithelial, myoepithelial, and stromal components. Hematoxylin and eosin stain.
Endoscopy_UCTN_Code_TTT_1AS_2AC
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