MATERIALS/METHODS
A 61-year-old woman was referred to the general Otolaryngology clinic
with the incidental finding of a left neck mass identified on CT scan.
Contrast-enhanced CT revealed a 3cm low attenuating lesion with a
punctate calcification, displacing the internal and external carotid
arteries anteromedially and internal jugular vein
posterolaterally(Figure 1A). The differential diagnosis included
metastatic lymphadenopathy or neurogenic tumor. Given these findings,
the patient was referred to interventional radiology for an image guided
biopsy. However, upon review, the interventional radiology team deferred
transcutaneous FNA given proximity of the mass to the great vessels. The
patient was then referred to the head and neck surgical oncology clinic
of the senior author for management. MRI with and without contrast
demonstrated a rim-enhancing, predominantly non-enhancing lesion with a
nodular enhancement at its medial portion, and foci of susceptibility
effect, suggestive of microhemorrhage(Figures 1B, C). Although,
schwannoma was high on the differential diagnosis, calcifications were
felt to be an unusual finding. The differential diagnosis included
metastatic lesions, particularly from the thyroid, and neurogenic tumor.
In office US confirmed that transcutaneous biopsy was not possible due
to the location of the internal and external carotid arteries in the
line of transcutaneous US-guided FNA. Open biopsy was felt to be a poor
choice due to potential for nerve injury in the case of a neurogenic
tumor, in addition to standard reasons to avoid open surgical biopsies
in cases of suspected neoplasm (scar, risk of seeding tumor, cranial
nerve injury). Options of observation and EPhUS were offered and after
informed consent, EPhUS was selected.
The patient was given general anesthesia and intubated orally. A tonsil
gag was placed to expose the pharynx. An Olympus BF-UC180F
Endoscopic Ultrasonography Bronchoscope (Tokyo, Japan) was placed
transorally into the pharynx(Figure 1D). The endoscope is equipped with
a 7.5 MHz convex ultrasound probe(Figure 1E). The angle of view is 90
degrees and the direction of view is 35 degrees forward and oblique. The
tip of this scope contains a balloon, which assists with acoustic
coupling of the ultrasound, however this is of little utility in the
pharynx. A working channel allows passage of a needle for FNA. The
endoscope, processing tower and monitor system allow duel display of
both the ultrasound and endoscopic images, including Doppler. Both
transnasal and transoral EPhUS are possible. In our experience both
require two people: an endoscopist and an assistant to hold the
endoscope in contact with the pharyngeal wall. The endoscope is passed
into the pharynx and then brought into contact with the pharyngeal
mucosa. Real time ultrasonographic imaging is then performed. In this
case example, the lesion in question, with the internal and external
carotid arteries on the lateral surface, are clearly identifiable
(Figure 1F). After confirmation of the lesion, FNA can be performed
(Figure 1G).
This needle used here is a retractable, 22g-g beveled, needle with a
stylet, which allows clearance of plugs. The external surface of the
needle is grooved, rendering it more hyperechoic, improving US
visualization. Once the target mass is identified, the needle is
advanced through the channel of the bronchoscope. Although the needle
can be extended to a length of 40mm, intrinsic safety mechanisms of the
device prevent excessive needle protrusion. Suction can be applied with
a 20-ml VacLoc syringe as needed. When an adequate biopsy is obtained,
the entire needle system is then withdrawn and the aspirated specimen is
removed by pushing preservative through the lumen. Both on-site and
final pathology confirmed the diagnosis of nerve sheath tumor. There was
minimal blood loss. The patient was observed in the post-anesthesia unit
and discharged in stable condition after examination confirmed no voice
changes, dysphagia or shortness of breath. When seen in follow up, she
was asymptomatic.