Brachial plexus schwannoma mimicking cervical lymphadenopathy: A case report with emphasis on imaging features

Abstract

Rationale: Brachial plexus schwannomas are rare benign tumors that are derived from Schwann cells. Because they are rare, and because of the complexity of the anatomy of the neck, these tumors can be a challenge to diagnose for radiologists and clinicians. In the present study, we describe a clinical case of brachial plexus schwannoma detected on ultrasonography (US), computed tomography (CT), and magnetic resonance imaging (MRI), and presenting as a palpable neck mass.

Patient concerns: A 49-year-old woman had a palpable mass in the right neck, which had been there for the last 1 year. Metastatic cervical lymphadenopathy was suspected in the primary health clinic; therefore, the patient was referred to our hospital.

Diagnoses: The right neck mass was a well-circumscribed oval soft tissue mass on US, CT, and MRI. US-guided core needle biopsy was performed and the mass was proved to be a schwannoma.

Interventions: The patient did not undergo surgical excision because the brachial plexus schwannoma was small and there was no accompanying neurological symptom.

Outcomes: The patient is being followed up regularly at the outpatient department.

Lessons: Brachial plexus schwannoma should be considered for a differential diagnosis in patients with a palpable neck mass, and imaging studies play an important role in diagnosing the brachial plexus schwannoma.

Figure 1

A and B, Normal left cervical/brachial plexus. A, Axial ultrasonography image showing left cervical nerve (dashed arrow) passing between anterior and posterior tubercles (black arrowheads) of the transverse process. B, Nerve (dashed arrows) passes between the prevertebral muscles and paravertebral muscles deep to the sternocleidomastoid muscle. C–E, A palpable mass in the right neck of a 49-year-old woman. Axial (C) and longitudinal (D) ultrasonography images showing a well-circumscribed, oval, homogeneously hypoechoic mass (white arrows) in the right neck. The mass has a continuity with hypoechoic linear structure suggestive of brachial plexus (black arrows). Longitudinal color Doppler image (E) showing no definite vascularity in the mass.

Figure 2

The pathologic specimen of the mass; A. In higher magnification, several pleomorphic cells of elongated nuclei with pinkish cytoplasm and a few sprinkled fibroblastic cells and inflammatory cells are seen (original magnification ×400); B. The elongated pleomorphic cells show diffuse positive expression for S-100 protein (original magnification ×100).

Figure 3

Axial (A) and coronal (B) computed tomography (CT) images showing well-circumscribed, oval, hypoattenuating mass (arrows) with poor enhancement within the muscle-fascia plane of the right neck. Axial fat-suppressed T2-weighted image (WI) (C) showing a hyperintense mass (arrow). Axial T1WI (D) showing an isointense mass (arrow). Axial contrast-enhanced T1WI (E) showing a homogeneous enhancement of the mass (arrow). Coronal fat-suppressed T2-weighted maximum intensity projection (MIP) image (F) showing the continuity of the mass (arrow) with the right C5 nerve (arrowheads).