PMC9884823_01
MRI of the brachial plexus showed the C5/C6 roots, upper and middle trunks and all strands of the left brachial plexus were significantly swollen and thickened, with T2W high signal, the right brachial plexus had good continuity, with no clear thickening and no signal enhancement (A). MRI showed multiple nodules within the brachial plexus in the left subclavian region (B), the two that could be distinguished were ~16 mm (C) and 11 mm (D) in diameter respectively.
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F1
Magnetic resonance imaging (MRI) of the brachial plexus revealed thickening and edema of the left brachial plexus (Figure 1).
Ultrasound of the brachial plexus showed a high degree of thickening of the C5 and C6 nerve roots, ~0.4 cm and 0.5 cm respectively (A, B); diffuse edema of the superior, middle, and inferior trunks were seen in the interosseous sulcus; Brachial plexus neuroma-like change of brachial plexus in the supraclavicular fossa, ~1.14 cm thick at most and 3.17 cm long (C, D).
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F2
Ultrasound of the left brachial plexus showed significant edema and thickening of the left brachial plexus roots, trunk, and strands, mostly pronounced in the supraclavicular fossa segment, with local thickening showing neuroma-like changes, ultrasound of the left upper arm nerve showed edema of some nerve bundles (Figure 2).
PET CT revealed increased radioactive uptake in the left brachial plexus (SUV max 24.4) (A, B), involving a length of 9.3 cm (C, D).
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F3
Further, positron emission tomography-computed tomography (PET-CT) revealed increased radioactive uptake in the left brachial plexus (SUV 24.4), indicating a tumor (Figure 3).
Pathology (tissue of brachial plexus swelling in the left supraclavicular fossa): diffuse lamellar arrangement of the spindle or oval cells, mild-moderate heterogeneity of the nuclei, nuclear schism 4/10HPF, some interstitial vitreous changes, chondrogenic differentiation visible in focal areas (A). Immunohistochemistry: Vimentin (+) (B), Ki-67 (25%+) (C), SOX10 (individual cells+) (D), S-100 (individual cells weakly+) (E), P120 (+) (F). In summary, a diagnosis of malignant peripheral schwannoma was considered.
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F4
Morphology and positive immunohistochemical presentations (Vimentin, Ki-67, SOX10, S-100, P120) of nerve biopsy confirmed an MPNST (Figure 4).