Schwannoma of Brachial Plexus

Abstract

Brachial plexus tumours are a rare entity. Schwannomas are benign nerve sheath tumours and only about 5% arise from the brachial plexus. Due to its rarity and complex anatomical location they can pose a formidable challenge to surgeons. We present a case of a young patient who presented with an axillary swelling three months after a lymph node biopsy from the same axilla, which turned out to be a Schwannoma arising for the medial cord of the brachial plexus.

Case Summary

A 17 year old male presented with swelling and pain in his left axilla of 15 days’ duration. On examination, he had a 5 × 4 cm firm swelling in the left axilla. There was no neurological deficit in the upper limb.

An FNAC was hemorrhagic. A CT scan of chest revealed a 7.6 × 4.3 cm mass in left axilla posterior to pectoralis major and anterior axillary artery which showed heterogeneous enhancement and suggestive of a lymph node mass or a neurogenic tumour (Fig. 1).

Fig. 1.

a. Contrast enhanced CT scan showing the isodense lesion in axilla with minimal enhancement. b. Sagittal reformatted image showing the tumour

During surgery for excision through an axillary approach, a 6 × 4 cm firm mass arising from the medial cord was found (Fig. 2). The tumour was enucleated avoiding any damage to cord. In the post operative period, the patient complained of loss of sensation over index finger and thumb. The histopathology of the tumour was consistent with Schwannoma.

Fig. 2.

Per-operative photograph of the tumour

Discussion

Brachial plexus tumours are rare comprising of only 5% of all tumours of upper limb [1]. The two most common brachial plexus region tumors are the Schwannomas and the Neurofibromas, both of which are benign and arise from the nerve sheath [2]. The most frequent site is in the head and neck, which comprises 25% of all Schwannomas, and only about 5% of Schwannomas present as brachial plexus tumours [3, 4]. Due to their rarity and complex anatomical location they form a formidable diagnostic and therapeutic challenge to surgeons [1].

Schwannomas are indolent tumors but may present with symptoms secondary to nerve compression. Grossly these tumours are oval or plexiform and may be pink, tan, yellow or gray [3]. Histologically, the terms Antoni type A and type B are used to describe varying growth patterns in Schwannomas.

Imaging studies are valuable in the pre-operative diagnosis. On CT, most Schwannomas are iso-dense relative to brain parenchyma. Calcification or areas of hemorrhage are rare and the enhancement pattern is typically homogeneous [5]. On MRI Schwannomas are iso-intense to hypo-intense on T1-weighted MRI and enhance with gadolinium [6].

Surgery is indicated for tumors that cause neurological dysfunction or pain or for any rapidly growing tumors with a suspicion of malignancy, and complete resection of these tumors results in cure [3].