Objective:

Background:

Tumor spread to peripheral nerves usually portends a poorer prognosis. Identification of such cases can have significant implications on management, outcomes, and patient counseling. While the clinical features in such patients have been previously described, there is a paucity of information on the pathologic features. We sought to review the microscopic findings on nerve biopsies in patients with breast cancer spread to the brachial plexus.

Design/Methods:

Review of the clinical, radiologic, and pathologic features of patients with brachial plexus perineurial invasion from metastatic breast carcinoma.

Results:

We found 19 patients with brachial plexus invasion from breast cancer who underwent nerve biopsies. Symptoms were on the left in twelve and on the right in seven. The most common initial neurologic symptom was pain (9/19). At presentation, all patients had pain and weakness, and 16 patients reported numbness. Panplexopathy was the most common pattern. Physical exam, electrodiagnostic studies, and imaging guided selection of fascicular biopsy site within the brachial plexus. Two patients did not have tumor involvement on nerve biopsy. The most common findings were generalized myelinated fiber loss (15/19), endoneurial inflammation (17/19), perineurial inflammation (10/19), and tumor preferentially involving the perineurium (8/17) or subperineurium (4/17). At average follow-up time of 4 years, 16 patients had passed away after an average of 20 months from diagnosis of brachial plexus invasion.

Conclusions:

Pain and weakness in a panplexopathy pattern are common in patients with brachial plexus invasion by breast adenocarcinoma. Nerve biopsies demonstrate tumor invasion predominantly in the perineurium/subperineurium, and inflammatory cells within the endoneurium and perineurium. We suspect that the tumor spreads within the nerve primarily via the perineurium/subperineurium, and the presence of the neoplasm induces an inflammatory response.