Rare case of a liposarcoma in the brachial plexus

Abstract

Introduction

A liposarcoma is a rare cancer of connective tissues that resemble fat cells under light microscopy.

Case History

A 73-year old female patient presented to our tertiary cancer centre with an eight-year history of a large, slow-growing painless mass in the right axilla. Magnetic resonance imaging showed a lipomatous, well-circumscribed mass of dimension 30 × 16 × 10cm extending towards the right clavicle and causing deformation to the right chest wall and right breast. Surgery revealed a large tumour that had stretched all three cords of the brachial plexus. Histopathology was consistent with a diagnosis of a low-grade liposarcoma. After a period of neuropraxia, the patient returned to normal activities 4 months after surgery.

Conclusions

Although extremely rare, low-grade liposarcomas of the brachial plexus should be considered in the differential diagnosis of a slow-growing axillary mass. Referral to a tertiary sarcoma centre is essential for an appropriate diagnosis, adequate treatment, and long-term follow-up.

Case History

A 73-year old female presented to our tertiary cancer centre with an eight-year history of a large, slow-growing, painless mass in the right axilla. She complained of discomfort and reduced range of motion in the right shoulder.

Examination revealed a large, non-tender mass encompassing the entire right axilla and extending above the right clavicle, pushing the right breast medially. She had reduced abduction in the right upper arm to 150° as well as reduced internal rotation. Magnetic resonance imaging (MRI) revealed a largely uniform, lipomatous, well-circumscribed mass of dimension 30 × 16 × 10cm extending towards the right clavicle and causing deformation to the right chest wall and right breast (Fig 1). As expected according to MRI findings, the core biopsy was indeterminate between lipoma and low-grade liposarcoma. Detailed discussion in the multidisciplinary meeting resulted in a management plan of marginal limb-preserving surgical excision.

Figure 1.

Magnetic resonance imaging of a lipomatous, well-circumscribed mass of dimension 30 × 16 × 10cm extending towards the right clavicle (a) causing deformation to the right chest wall and right breast (b)

Intraoperatively, the mass was found to stretch all three cords of the right brachial plexus (Fig 2). Histology of the completely excised tumour (Fig 3) was consistent with a lipoma-like, low-grade liposarcoma, and no further treatment was required. After a period of weakness in right deltoid, infraspinatus and teres minor muscles as a result of neuropraxia, she returned to normal daily activities 4 months after surgery.

Figure 2.

Intraoperative findings: sarcoma mass (a) stretched all three cords of the right brachial plexus (b)

Figure 3.

Large liposarcoma excised completely with the right brachial plexus kept intact

Discussion

Liposarcoma is the most common soft-tissue sarcoma, and accounts for >20% of sarcomas in adults.¹ Atypical lipomatous tumours/well-differentiated liposarcomas are low-grade malignant mesenchymal neoplasms with a high propensity to local recurrence and potential to dedifferentiate to higher grades. However, results of studies on local recurrence and dedifferentiation vary, and unified treatment and follow-up plans are lacking.²

Usually, a soft-tissue sarcoma presents as an asymptomatic mass. The differential diagnosis of a soft-tissue mass is a malignant lesion, desmoid tumour or benign lesion. Our case highlights the importance of consideration of soft-tissue swellings and growths as being malignant until the opposite has been demonstrated. A core biopsy of a large lipomatous lesion cannot be used to differentiate between a benign lipoma and lipoma-like liposarcoma. Unlike high-grade lesions characterised by different degrees of heterogeneous internal structure, lipoma-like liposarcomas demonstrate a homogenous, largely lipomatous appearance with thick septa, enhancement or evidence of local invasion.³ In general, limb-sparing surgery is preferred to achieve local control of tumour with minimal morbidity. This strategy is particularly important in low-grade, slow-growing lesions because radical surgery (eg four-corner amputation) would cause significant unjustified functional loss. The surgeon and pathologist should document surgical margins extremely carefully and thoroughly by evaluating a resected specimen. The recommended treatment for liposarcoma is radical local excision of the tumour while trying to preserve the limb. Lipomatous tumours in the axilla are extremely rare,³ whereas only one case of liposarcoma of the brachial plexus has been documented.⁵ Size of the tumour and its relationship to the brachial plexus determine functional recovery after surgery. In spite of adequate excision, local recurrences are possible, so long-term follow-up (clinical and imaging) is recommended.

Conclusion

Although extremely rare, low-grade liposarcomas of the brachial plexus should be considered in the differential diagnosis of a slow-growing axillary mass. Referral to a tertiary sarcoma centre is essential for an appropriate diagnosis, adequate treatment, and long-term follow-up.