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We report the case of a 42-year-old female who had received treatment for carcinoma left breast, now presenting with pain in the left upper limb for 2 months and paraesthesia for 1 month. Magnetic resonance imaging of the brachial plexus revealed altered signal intensity involving divisions and cords of the brachial plexus on the left side. 18F fluorodeoxyglucose (FDG) positron emission tomography-computed tomography revealed moderately increased FDG concentration in multiple ill-defined nodules, along the left brachial plexus suggestive of metastatic brachial plexopathy.
Keywords: 18F fluorodeoxyglucose positron-emission tomography/computed tomography, carcinoma breast, magnetic resonance imaging, metastatic brachial plexopathy
How to cite this URL:
Medara ST, Sricharan K B, Krishna Mohan V S, Manthri RG, Lakshmi A Y, Kalawat TC. 18F fluorodeoxyglucose positron-emission tomography–computed tomography in the diagnosis of brachial plexopathy in carcinoma breast: A case report and review. J Clin Sci Res [Epub ahead of print] [cited 2022 Aug 20]. Available from: https://www.jcsr.co.in/preprintarticle.asp?id=330769 |
| Introduction | |  |
Breast carcinoma is the most common cancer among females all over the world, accounting for 23% of incidence and 14% of cancer-related deaths every year.[1] Due to changes in lifestyle, i.e., adoption of western styles, increased urbanisation and increased life expectancy, the incidence of breast cancer has been increasing. About 30% of patients treated for localised breast cancer develop metastatic disease.[2] Breast cancer commonly metastasises to the local and distant lymph nodes, bones, liver, lungs, brain and pleura.[3] Brachial plexopathy is a rare condition, which causes pain and disability, with an overall incidence of <0.5% in breast cancer patients.[4] Brachial plexopathy in breast cancer can occur by the metastatic spread of disease or due to radiation injury to brachial plexus.[5]
| Case Report | | |
A 42-year-old female, who was a known case of carcinoma left breast, underwent modified radical mastectomy, followed by adjuvant chemotherapy with four cycles of taxanes and adjuvant radiotherapy with a total dose of 50 Gy. Histopathology revealed infiltrating duct cell carcinoma, pathological staging PT1cN2aMx. On immunohistochemistry, oestrogen and progesterone receptor status was negative and Her2 status was equivocal (2+).
On follow-up, the patient was symptom free for 1 year, now presented with pain in the left arm and paraesthesias in the middle and ring fingers initially, followed by paraesthesia up to wrist for 5 months. Weakness is insidious in onset, associated with difficulty in handling objects, difficulty in buttoning and unbuttoning, difficulty in raising the left arm above the shoulder and there is thinning of the left upper limb. On central nervous system (CNS) examination, sensory system examination showed decreased pinprick sensations over the dorsal aspect of the forearm of the left upper limb. Motor nervous system examination showed decrease in tone and power in the left upper limb. Furthermore, biceps, triceps supinator reflexes are absent. The rest of the CNS examination is normal. Hence, suspected diagnosis of radiation injury to the left brachial plexus was made.
On electroneuromyography (ENMG), the left median nerve motor conduction shows normal distal latency, normal conduction velocity with decreased compound motor nerve action potential (CMAP) amplitude and signal prolonged F-wave compared to the right median nerve. The left radial nerve shows normal distal latency and normal conduction velocity with decreased CMAP amplitude compared to the right radial nerve.
Magnetic resonance imaging (MRI) revealed altered signal intensity along divisions and cords of the brachial plexus on the left side and oedema in muscles over the left lateral chest wall and upper one-third of the arm with soft-tissue deposits in the axilla and along the brachial plexus [Figure 1], with this diagnosis of suspected metastatic recurrence being made. | Figure 1: Coronal T1-weighted magnetic resonance imaging showing altered signal intensity along divisions and cords of the brachial plexus on the left side
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Later, whole-body 18F fluorodeoxyglucose (FDG) positron-emission tomography (PET)–computed tomography (CT) was done to validate MRI findings as well as for metastatic workup. FDG-PET scan revealed moderately increased FDG concentration in multiple ill-defined nodules, along the left brachial plexus largest measuring 1.3 cm × 1.1 cm with maximum standardised uptake value of 5.8 suggestive of metastatic brachial plexopathy (MBP) [Figure 2]. Intensely increased FDG concentration was noted in enlarged right upper paratracheal lymph nodes and metabolically active metastatic soft-tissue deposits in the lateral chest wall and multiple ill-defined isodense lesions in both the lobes of the liver suggestive of liver metastases [Figure 2]. The patient was given palliative chemotherapy with taxanes, and later, she started recovering symptomatically. | Figure 2: MIP image (a), axial CT (b) and fused PET-CT (c), coronal CT(d); and fused PET-CT (e) showing multi focal hyper metabolic activity in ill-defined nodules, along the left brachial plexus, largest nodule measuring 1.3 cm × 1.1 cm with maximum standardised uptake value of 5.8, more in favour of metastatic brachial plexopathy (a, arrow). Multiple mediastinal lymph nodes and multiple liver metastases are also noted on maximum intensity projection image
MIP = Maximum intensity projection; CT = Computed tomography; PET-CT = Positron emission tomography-computed tomography
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| Discussion | | |
The most common cause of brachial plexopathies in adults includes primary and secondary tumours where primary tumours are seen in younger adults and they include benign conditions like schwannoma or may result from genetic conditions like neurofibroma.[6] Secondary neoplasms are commonly seen in older adults where breast and lung cancers are the leading causes that can cause plexopathy either by direct invasion or by metastasis.[7] Radiotherapy is established adjuvant therapy for regional breast cancer, which may result in radiation fibrosis when a dose exceeds 6000 cGy.[7] Therefore, MBP and radiation-induced brachial plexopathy (RBP) remain the most common causes, whose differentiation is needed for further management.[8] Both differ in their prognosis, management, overall survival and quality-adjusted life years. Till date, there is no single modality of investigation that can accurately differentiate between the two.
Both of these entities differ slightly in their anatomy. Involvement in MBP is more focal and more commonly involves the lower trunk, i.e., C8–T1, posterior to anterior scalene muscles. RBP involves the upper trunk, i.e., C5–C7, along the lateral border of the anterior scalene muscles.
Symptoms follow the same pattern of nerve distribution. Painful lower trunk lesions with Horner's syndrome are classical in MBP, whereas RBP is painless, with paraesthesias as presenting complaint.[9] ENMG findings associated with myokymic discharges are most common with RBP than in MBP but are not pathognomonic.[10]
However, these clinical and ENMG findings always cannot differentiate between MBP and RBP; hence, imaging studies like PET-CT and MRI are necessary.[11]
On MRI, focal mass with irregular margins and heterogeneous appearance usually suggests malignancy. MBP usually has low signal intensity on T1-weighted images and high signal intensity on T2-weighted (T2W) images with post-contrast enhancement. Occasionally, it might demonstrate low signal intensity on T2W images.[12]
RBP on MRI shows diffuse, uniform swelling with T2 hyperintensity and mild contrast enhancement, making it difficult to differentiate from MBP.[13] As morphological and signal intensity of MBP overlap with those of RBP, it is difficult for MRI to differentiate between the two when lesions are subtle and do not follow the classical pattern.[14]
18F FDG PET-CT provides functional information with CT providing anatomical correlation can be useful to differentiate MBP from RBP due to differences in their metabolism. Malignant tumour accumulates more 18F FDG than fibrosed tissue. Therefore, RBP shows mild activity with linear uptake usually from supraclavicular or infraclavicular aspect to lateral aspect of the axilla.[15],[16] MBP shows focal, intensely increased radiotracer uptake. Hence, identification of specific pattern of uptake and correlation with clinical features can help in early diagnosis and thereby differential treatment approach[17] that includes chemotherapy and radiotherapy for MBP and transdermal electrical nerve stimulation and neurolysis with omentoplasty have been tried in RBP.[8] Further, FDG-PET can also be used for whole-body metastatic workup for re-staging and directing treatment. Therefore, FDG-PET is a useful imaging technique to study the brachial plexus in breast cancer patients and that it may also be useful to monitor treatment efficacy as well.[17]
Brachial plexopathy leads to pain and disability causing hindrance in day-to-day life. Hence, its early diagnosis and prompt treatment is necessary to provide disease-free survival and good performance status. Therefore, 18F FDG PET-CT should be used whenever clinical signs and symptoms of brachial plexopathy in a known case of breast cancer are warranted. It plays an important adjunctive role to MRI and can potentially be a one-stop investigation not only for diagnosing MBP but also for differentiating if from RB. Further, 18F FDG PET-CT can also identify metastatic disease outside the axilla and can be useful to monitor treatment efficacy as well.
Financial support and sponsorship
Nil.
Conflicts of interest
The authors are faculty members/Postgraduate students/residents of Sri Venkateswara Institute of Medical sciences, Tirupati, of which Journal of Clinical and Scientific Research is the official Publication. The article was subject to the journal's standard procedures, with peer review handled independently of these faculty and their research groups.
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Correspondence Address:
V Sai Krishna Mohan,
Assistant Professor, Department of Nuclear Medicine, Sri Venkateswara Institute of Medical Sciences, Tirupati 517 507, Andhra Pradesh
India
 Source of Support: None, Conflict of Interest: None DOI: 10.4103/JCSR.JCSR_124_19
[Figure 1], [Figure 2] |
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