PMC9236828_01
Imaging findings: contrast-enhanced computed tomography ((a) horizontal section and (b) coronal section) showing a well-defined, 85 x 50 mm tumor (arrow) in the right neck. There was no contrast effect inside the tumor. Contrast-enhanced MRI ((c) T1-weighted images, (d) T2-weighted images, and (e) STIR) shows the tumor had low signal intensity on T1-weighted images, high signal intensity on T2-weighted images, and low signal intensity on STIR. Variable signal intensity areas were seen outside the tumor.
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Contrast-enhanced computed tomography (CT) showed a well-defined 85 x 50 mm tumor on the right neck (Figures 1(a) and 1(b)), with low radiodensity, equivalent to that of adipose tissue. STIR (Figures 1(c)-1(e)). Some flat areas of variable signal intensity were seen outside the tumor.
Fine needle aspiration cytology findings (Papanicolaou stain). There were a small number of mesenchymal cells with spindle-shaped nuclei.
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Fine needle aspiration cytology (FNAC) showed a small number of mesenchymal cells with spindle-shaped nuclei (Figure 2), consistent with a schwannoma.
Intraoperative findings: the nerve of origin at the lower edge of the tumor ((a) arrow) and tumor in the neuroepithelium (arrow, epineurium; (b)*, tumor) were visible. The excised yellowish specimen was 85 x 50 x 35 mm (c). Histopathologically, bifurcated growth of mature adipocytes with sparse fibrous septa was observed (d) (H&E staining).
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The peritumor area was dissected from the anterior border of the sternocleidomastoid muscle, and the nerve of origin and its course were identified at the superior and inferior edges of the tumor (Figure 3(a)). The fibrous connective tissue was dissected to reach the true fatty and yellowish tumor capsule (Figure 3(b)). Histopathological examination of the excised yellowish specimen (85 x 50 x 35 mm; Figure 3(c)) revealed bifurcated growth of mature adipocytes with sparse fibrous septa on H&E staining (Figure 3(d)). Similar findings were also observed in what was thought to be the enriched component on preoperative imaging (Figure 3(d)).