The authors report the case of a 49-year-old female who presents a recent worsening neck pain and right C7 radiculopathy, with a visual analogue scale (VAS) for arm pain at 10/10 despite using tramadol and pregabalin. The Neck Disability Index (NDI) at presentation is 25/50 (50%), indicating severe impairment. The neurological examination shows right triceps palsy with muscular strength at M4/5 on the Medical Research Council (MRC) scale.

Cervical MRI shows a cystic mass at the right C6-C7 foramen with peripheral ring enhancement (Fig. 2). A CT-angiogram reveals a close relationship between the tumor and the V1 segment of the vertebral artery (VA) without significant arterial stenosis, but with enlargement of the right C6-C7 foramen and intralesional calcifications (Fig. 3). Due to severe disability and the neurological deficit, the patient underwent surgical resection. Due to the foraminal localization with predominant ventral extension and foraminal widening, the authors opt for a retrojugular approach. This approach provides direct access to the lesion with minimal bone resection and offers good control of the ventrally displaced VA.

Pre-operative cervical MRI. Panel a: Sagittal T1-weighted images; Panel b: Axial T2-weighted images; Panel c: Coronal oblique T2-weighted image; Panel d: Axial T1 Fat sat weighted image after contrast injection

The description of the retrojugular approach is the following: through a skin incision extending along the anterior border of the sternocleidomastoid muscle (SCM), a subplatysmal flap is raised anteriorly until the midline and posteriorly up to the trapezius. The SCM is mobilized to expose the carotid sheath and, superiorly, the spinal accessory nerve. The internal jugular vein (IJV) is skeletonized and mobilized along with the vagus nerve. The transverse cervical artery, scalene muscles, phrenic nerve, and trunks of the brachial plexus are then identified. The V1 segment of the vertebral artery (VA) is also identified but not mobilized or transposed.

Cervical CT shows a right C6-C7 foraminal lesion with intralesional calcifications (white circle). Panel a: axial images. Panel b: sagittal images, the black arrow shows a right C6-C7 foraminal mass in close relationship with the vertebral artery without arterial obstruction. Panel c: coronal images

The C6-C7 foramen is identified under fluoroscopy, and the anterior part of the C7 transverse process is removed under robotic exoscopic visualization (Modus V, Synaptive Medical) using an ultrasound bone scalpel (Sonopet, Stryker) to access the neural foramen. Due to an error of localization, the C6 transverse process was removed instead of C7, causing brisk VA bleeding. The arterial bleeding is controlled using patties and coagulation at 20 Malis units, 3 watts for less than a second to progressively close the arterial breach. After verification with fluoroscopy, the C7 transverse process was identified and removed using the ultrasound scalpel.

After visualization of the foraminal tumor, careful drilling of the anterior margin of the C6 and C7 vertebral bodies permits the enlargement of the neural foramen. Piecemeal (intralesional) resection is accomplished under robotic exoscope magnification using standard microsurgical techniques. The tumor appears covered by periosteum, with the right C7 nerve root identified and preserved. The tumor is resected through the neural foramen with no intradural portion identified. At the end of the procedure, the resection is considered with positive margins [8]. No fusion is required.

In the immediate postoperative period, the patient presents regression of the right C7 radicular pain and improvement of the triceps palsy (M4+/M5 MRC). As a complication, the patient developed right Horner’s palsy. Postoperative CT angiogram shows no right VA dissection with complete canalization of the vessel.

Histology (Fig. 4) shows a well-differentiated cartilaginous lesion with small lobules of chondrocytes embedded in a chondroid, partially myxoid matrix. Cellularity is slightly variable, but the chondrocytes display a small nucleus with no significant atypia; no mitotic activity and no necrosis are seen. The immunohistochemical study shows cytoplasmic reactivity to S100 protein and nuclear SOX9 reactivity, consistent with the cartilaginous nature of the tumor. There is no reactivity to epithelial markers (AE1/AE3, EMA) and brachyury. The definitive diagnosis is in favor of juxtacortical chondroma or enchondroma.

Histology (x200; hematoxylin-eosin stain) reveals a purely well-differentiated cartilaginous tumor, composed of small lobules of bland chondrocytes (Panel a) alternating with paucicellular areas showing chondrocytes arranged in isogenic columns (Panel b)

At 36 months of follow-up, the patient is pain-free with complete recovery of right triceps palsy and partial regression of the right Horner’s syndrome. The NDI score at 3 years is 3/50 (6%). Follow-up MRI (Fig. 5) shows the right C6-C7 foramen with no tumor recurrence.

Follow-up cervical MRI with contrast-enhanced T1 sequences (Panel a sagittal, Panel b axial views) showing absence of tumor recurrence at the C6-C7 right foramen (white arrows)

The literature review identifies a total of 10 patients who underwent surgery for subaxial foraminal chondroma [2, 9, 14, 19, 25, 29, 31,32,33, 36], with the addition of the 11th case reported by the authors. The patients’ characteristics are outlined in Table 1. The mean age at diagnosis is 33.6 years (range: 10–73), and gender distribution shows a female prevalence (F = 7:4). Most patients report neurological symptoms at diagnosis. The clinical manifestation is radiculopathy in 33% (4/11) and myelopathy in 16% (2/11), while a combination of radiculopathy and myelopathy is present in 33% (4/11). 18% (2/11) of patients present with symptoms related to tumor mass effects on the surrounding neck structures (dysphagia, hoarseness, and cervical mechanical pain).

The most frequently involved vertebral level is C4-C5 (54.6%, 6/11), followed by C5-C6 (18.2%, 2/11), C6-C7 (18.2%, 2/11), and C7-T1 (9%, 1/11). Preoperative foraminal enlargement is present in 63.6% (7/11) of patients. Surgical resection is performed via the anterior approach in 18.2% (2/11) of patients with vertebral body resection and concomitant cervical instrumentation. The anterolateral approach is selected in 27.2% (3/11) of patients and the posterior approach in 54.6% (6/11) of patients, with only one patient requiring both anterior and posterior instrumentation. Gross total resection (GTR) is achieved in 81.1% (9/11), in one patient (9%) subtotal resection (STR) is decsribed and in one patient the extent of resection is not evaluable. No patient received adjuvant treatment (radio- or chemotherapy). The mean follow-up duration is 18 months (range: 3–42 months). All patients treated with GTR are considered as cured at follow-up with no tumor recurrence, while the only patient with STR presenting tumor recurrence 12 months postoperatively thus undergoing second surgery. For the patients with available follow-up data (10/11, 90.9%), McNab’s score is evaluated as excellent in 60% (6/10), good in 30% (3/10), and poor in one patient (10%).