April 10, 2009
4 min read

Is this neoplastic or radiation-induced brachial plexus syndrome?

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A 54-year-old woman was initially diagnosed with left breast cancer 11 years ago. Based on left lumpectomy, axillary lymph node dissection and imaging she was staged as cT2N1M0. Her tumor was ER/PR negative and HER2-neu low. She received adjuvant chemotherapy with doxorubicin and cyclophosphamide followed by paclitaxel. She received radiation to left breast, supraclavicular and intramammary lymph nodes.

At the end of 2008, she presented with persistant left shoulder pain despite conservative management. A shoulder MRI showed diffuse edema of the pectoralis major and minor muscles, deltoid muscle and mild arthosis of the acromioclavicular joint. A few weeks later she developed tingling numbness and weakness in the left upper extremity. PET/CT was ordered and showed an asymmetric soft tissue with hazy infiltration of the adjacent fat. It was deep to the left pectoralis muscles and extended into the left axilla.

Munir Ghesani, MD
Munir Ghesani

On corresponding functional images, there was mild increased metabolic activity in this region, with a maximum SUV of about 3.4. There was also atrophy of the left pectoralis major, pectoralis minor, deltoid muscle, and infraspinatus muscle. Given her remote history of surgery and radiation therapy, the pattern was felt to represent recurrent breast carcinoma and not post-therapy changes.

A core needle biopsy of the left chest wall soft tissue mass was nondiagnostic. At the same time an EMG done by neurology showed brachial plexopathy. A MRI spine and brachial plexus showed mass in the left supraclavicular fossa with involvement of brachial plexus. The plexus were extensively clumped and demonstrated abnormal contrast enhancement. Abnormal thickening and enhancement extended medially along the trunks to involve the root at the C6/C7 level, where it continued along the left lateral aspect of the spinal canal.

This enhancing soft tissue contacted the left side of the spinal cord with slight cord flattening without frank cord compression. The pattern was highly suggestive of recurrent breast carcinoma with perineural spread. A brain MRI was negative for metastases. Her screening mammogram from three months ago was normal.

On a follow-up visit, she had persistant left shoulder pain and weakness in the left upper extremity. Due to the location and progressive symptoms repeat biopsy was not attempted. Given the absence of other lesions or hypermetabolic activity on the imaging studies, this could represent either a recurrent or primary breast cancer with brachial plexus involvement. She received radiation; however, the dose was limited due to prior treatment. She was started on palliative chemotherapy pending HER2-neu testing by FISH.

Figure 1: CT, PET, maximum intensity projection (MIT) PET, and PET/CT fusion images
Figure 1: Clockwise from upper left – CT, PET, maximum intensity projection (MIP) PET, and PET/CT fusion images. The axial CT image demonstrates asymmetric infiltration of the neurovascular bundle and fat in the left supraclavicular region compared to the right. This is associated with mild increased FDG uptake with a maximum SUV of 3.4. This infiltration was noted to extend from deep to the pectoralis muscles to the axilla.

Figure 2: Precontrast T1 weighted MR image

Figure 2: Postcontrast fat suppressed T1 weighted MR image

Figure 2: LEFT – Precontrast T1 weighted MR image demonstrates asymmetric infiltration of the neurovascular bundle and fat in the left supraclavicular region as was shown on the PET/CT. RIGHT – Postcontrast fat suppressed T1 weighted MR image demonstrates diffuse enhancement of the infiltrating lesion.

Figure 3: Postcontrast fat suppressed T1 weighted MR image

Figure 3: Postcontrast fat suppressed T1 weighted MR image

Figure 3: Postcontrast fat suppressed T1 weighted MR images demonstrate abnormal thickening and enhancement of the C7 nerve root as well as enhancing soft tissue contacting the left side of the spinal cord with slight cord flattening. This finding was also seen involving the C6 nerve root to a lesser extent.
Source: M. Ghesani


Brachial plexus syndrome, with regards to oncological etiology, can be either from neoplastic process or radiation-induced injury. Neoplastic etiology can be either primary tumors (schwanommas or neurofibromas) or metastatic disease (lung, breast, lymphoma, thyroid). Metastatic diseases most commonly involve the lower trunks with radicular pain being the most common complaint, and motor weakness or reflex abnormalities being the most common physical finding. Although radiation-induced plexopathy is usually seen a few weeks to months after radiation and exact etiology is unclear, clinically these patients have less pain and more paresthesias and weakness than neoplastic brachial plexopathy.

FDG-PET was done in 19 patients with breast cancer and symptoms referable to brachial plexus involvement; 14 patients had increased uptake within brachial plexus, one patient had increased uptake in the chest wall and four patients had a normal study. When a CT was done in nine patients with increased 18-FDG uptake in the brachial plexus, only three patients had clear involvement of brachial plexus. PET is useful in identifying malignancy involving brachial plexus; however, a larger sample is required to confirm these findings. EMG study is helpful in localizing the trunk involvement. An MRI is more sensitive than a CT in imaging brachial plexus. Treatment of brachial plexopathy from neoplastic etiology is radiation, physical therapy and optimal pain control.

The above case illustrates low uptake of 18FDG in the area of brachial plexus several years after surgery and radiation therapy, favoring recurrent breast carcinoma rather than post-therapy changes. This was further supported by presence of an associated soft tissue mass on MRI, and evidence of perineural spread outside the radiation therapy field.

Vamsee Torri, MD, is a Fellow in Hematology/Oncology at St. Luke’s-Roosevelt Hospital Center.

Neilesh Gupta, MD, is a Radiology Resident at St. Luke’s-Roosevelt Hospital Center.

Munir Ghesani, MD, is Associate Clinical Professor of Radiology at Columbia University College of Physicians and Surgeons and Attending Radiologist at St.Luke’s-Roosevelt Medical Center.

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