Teaching Case

An 81-year-old woman presented to a general practitioner with a palpable mass in the back of the neck. The patient experienced discomfort and pain when turning her head towards the left. The patient had no relevant medical history, or neurological or other complaints.

Ultrasound showed a well-defined, heterogeneous, hypoechoic mass located subcutaneously, dorsally and laterally to the cervical spine (Figure 2). There was fluctuation within the mass. There was no internal flow with colour flow Doppler.

A subsequent non-contrast CT of the cervical spine showed a subcutaneous, well-defined mass with a calcified rim on the level of C3–C4 (Figures 1a and 1b). The mass originated from the adjacent facet joint and measured 3.5 x 1.5 x 2 cm. There was marked degeneration of the ipsilateral facet joint and neural foraminal narrowing.

A subsequent non-contrast MRI showed a subcutaneous, well-defined mass on the level of C3–C4. The mass showed hypointensity on both T1 and T2. The T2-weighted hypointensity was likely due to rim calcifications. There was neural foraminal narrowing.

Synovial cysts are benign, fluid-filled cystic dilatations that can arise from any synovial joint in the body [1]. Spinal synovial cysts are most frequently encountered in the lumbar region at the L4–L5 level and are associated with osteoarthritis of the facet joint [2] as well as with spinal degenerative joint and disk disease in general [3]. They can occur due to trauma and congenital factors [1]. Expansion of the synovial cyst may cause compression of nerve roots [3], causing neurological symptoms. However, synovial cysts in the cervical region are very rare [1].

Spinal synovial cysts are usually asymptomatic and discovered incidentally, although they can present with back pain and radiculopathy. If symptomatic, imaging is needed to make the diagnosis and to exclude differential diagnosis [2].

CT and MRI can both confirm the diagnosis by showing a cystic lesion originating from an, often osteoarthritic, facet joint. The lesion may contain luminal gas or rim-like calcifications. CT or MRI can help visualise neural foraminal compression, and thus, may explain the cause of the patient’s back pain or radiculopathy. The diagnosis cannot be made with conventional radiography alone [2].

Spontaneous regression of spinal cysts has been reported with immobilisation [3]. Treatment options include external immobilisation, oral corticosteroids and/or percutaneous aspiration followed by corticosteroid injections. Surgical options include excision of the lesion with or without decompression and fusion of the facet joint [3]. Imaging combined with the severity of the patient’s symptoms is necessary to help guide the choice of treatment [2].

In this case, due to the patient’s discomfort and pain on rotation of the neck, the orthopaedic surgeon opted for surgical removal of the lesion.

Spinal synovial cysts are rare, even more so in the cervical region. They are benign lesions with none or often mild symptoms. There are multiple treatment options and imaging is needed to confirm the diagnosis [2].

Written informed patient consent for publication was obtained prior to submission.