PMC6486389_01
(
A-C
) Positron emission tomography-computed tomography (PET CT) was performed, which demonstrated increased fluoro-2-deoxy-d-glucose uptake in both masses (standardized uptake value of 7.3 for the larger mass and 2.7 for the smaller mass).
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A positron emission tomography (PET) CT was performed, which demonstrated increased fluoro-2-deoxy- d -glucose uptake in the high cervical mass and, to a lesser degree, in the mass located within the posterior triangle of the neck ( Fig. 1 ).
Magnetic resonance imaging (MRI) neurogram demonstrated a larger 4.6 x 3.2 x 2.5 cm mass deep to the left sternocleidomastoid muscle just below the angle of the mandible
(A-C)
and a bilobed 2.4 x 2.2 x 1.3 cm mass in the left posterior supraclavicular region
(D-F)
.
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Prior to proceeding, a magnetic resonance neurogram was obtained ( Fig. 2 ).
Further imaging characterization of lesions.
(A)
Diffusion tensor imaging with tractography demonstrated abnormal thickened nerve fibers coursing through the two spinal accessory nerve tumors.
(B)
Axial diffusion weight imaging (left) and apparent diffusion coefficient (ADC) images (right) of the lesions. ADC values were 1.3 x 10
-6
and 1.8 x 10
-6
mm
2
/second for the larger and smaller masses, respectively.
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Tractography demonstrated that the two lesions appeared to originate from the spinal accessory nerve and that apparent diffusion coefficient values were elevated in both masses, supporting the diagnosis of a less aggressive tumor ( Fig. 3 ). 
Intraoperative findings.
(A)
Two separate incisions were required to remove both lesions.
(B)
The smaller bilobed lesion mass was accessed through the posterior triangle of the neck and was located on the distal spinal accessory nerve.
(C)
The larger more proximal mass was approached medial to the sternocleidomastoid muscle in the upper neck. Both masses underwent a gross total resection.
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The patient was positioned with her head turned slightly to the right with the neck extended ( Fig. 4A ). The tumor was found to be located on the distal spinal accessory (cranial nerve XI) nerve, with evidence of trapezius activation with nerve stimulation ( Fig. 4B ). A separate incision was made in the upper cervical region to approach the larger second mass located lateral and deep to the SCM muscle, which was reflected medially ( Fig. 4C ).