Unusual brachial plexus lesion: Hematoma masquerading as a peripheral nerve sheath tumor

Malignant peripheral nerve sheath tumors (MPNSTs) of the brachial plexus have unique radiographic and clinical findings. Patients often present with progressive upper extremity paresthesias, weakness, and pain. On magnetic resonance (MR) imaging, lesions are isointense on T1-weighted and hyperintense on T2-weighted sequences, while also demonstrating marked enhancement on MR studies with gadolinium diethylenetriamine pentaacetic acid. On the basis of their characteristic MR imaging features and rapid clinical progression, two brachial plexus lesions proved to be organizing hematomas rather than MPNST.

A 51-year-old male and a 31-year-old female were both assessed for persistent and worsened left-sided upper extremity pain, paresthesias, and weakness. In both cases, the MR imaging of the brachial plexus demonstrated an extraspinal enhancing lesion located within the left C7-T1 neuroforamina.

Although the clinical and radiographic MR features for these 2 patients were consistent with MPNSTs, both lesions proved to be benign organizing hematomas.

These two case studies emphasize that brachial plexus hematomas may mimic MPNSTs on MR studies. Accurate diagnosis of these lesions is critical for determining the appropriate management options and treatment plans. Delaying the treatment of a highly aggressive nerve sheath tumor can have devastating consequences, whereas many hematomas resolve without surgery. Therefore, if the patient has stable findings on neurological examination and a history of trauma, surgical intervention may be delayed in favor of repeat MR imaging in 2-3 months to re-evaluate the size of the mass.