A giant plexiform schwannoma of the brachial plexus: case report

Abstract

We report the case of a patient who noticed muscle weakness in his left arm 5 years earlier. On examination, a biloculate mass was observed in the left supraclavicular area, and Tinel's sign caused paresthesia in his left arm. Magnetic resonance imaging showed a continuous, multinodular, plexiform tumor from the left C5 to C7 nerve root along the course of the brachial plexus to the left brachia. Tumor excision was attempted. The median and musculocutaneous nerves were extremely enlarged by the tumor, which was approximately 40 cm in length, and showed no response to electric stimulation. We resected a part of the musculocutaneous nerve for biopsy and performed latissimus dorsi muscle transposition in order to repair elbow flexion. Morphologically, the tumor consisted of typical Antoni A areas, and immunohistochemistry revealed a Schwann cell origin of the tumor cells moreover, there was no sign of axon differentiation in the tumor. Therefore, the final diagnosis of plexiform Schwannoma was confirmed.

Figure 1

MRI images. Magnetic resonance imaging images. Magnetic resonance imaging showed a continuous, multinodular, plexiform tumor from the left C5 to C7 nerve root along the course of the brachial plexus to the left brachia. The tumor showed the same intensity as the muscle on T1-weighted images (T1WI), and slightly higher intensity on T2-weighted images (T2WI). Gadolinium-enhanced images (T1WI+C) showed no enhancement of the tumor. There was no sign of the tumor inside the vertebral canal.

Figure 2

operative findings. Operative findings. The median and musculocutaneous nerves were extremely enlarged by the tumor and showed no response to electric stimulation. There was no abnormality in the ulnar nerve. Triangle; ulnar nerve Wide arrow; enlarged median nerve Narrow arrow; musculocutaneous nerve.

Figure 3

Histological findings of the excised specimen. A. Hematoxylin and eosin staining (×40). Hematoxylin and eosin staining (×40). The tumor consisted of varying hypertrophic peripheral nerve fascicules showing a plexiform pattern, along with fibrous connective tissues.B. Hematoxylin and eosin staining (×100). Hematoxylin and eosin staining (×100). Antoni A areas, which composed main part of the tumor. A nuclear palisading pattern was focally observed. C. Masson trichrome staining (×100). Masson trichrome staining (×100). The fibrous connective tissues around the tumor were roughly stained. Immunohistochemistry for S-100 protein (×100). Immunohistochemistry for S-100 protein (×100). The tumor cells were strongly positive for S-100 protein.

Figure 4

Immunohistochemistry for neurofilament (×100). Immunohistochemistry for neurofilament (×100). There were no neurofilamment positive areas indicative of axons inside or outside the tumor.

Figure 5

Sixteen months after the operation. Sixteen months after the operation. By latissimus dorsi transportation, the patient acquired elbow flexion up to 100 degrees.