Gamma Knife radiosurgery for a recurrent craniocervical junction solitary fibrous tumour

Abstract

Spinal solitary fibrous tumour (SFT) is an uncommon tumour with few cases reported in the literature. It rarely originates at the craniocervical junction. To our knowledge, only eight cases of spinal SFT located at the craniocervical junction have been reported in the literature. We presented a patient with a craniocervical junction SFT and discussed its clinical presentation, radiological features, pathology, management and outcome. This was the first patient reported in the literature with a recurrent craniocervical junction SFT treated with Gamma Knife radiosurgery. The treatment reduced the tumour volume by more than 85% within 12 months.

Background

Haemangiopericytoma, a rare central nervous system (CNS) tumour, was first described in 1942 by Stout and Murray.¹ These tumours accounted for 1% of all CNS tumours, most commonly occurring in the brain but rarely in the spine or craniocervical junction.² Patients with this tumour frequently presented late local recurrences and extraneural metastasis.³ The tumour can be found in other body parts, most commonly in the extremities, pelvis, retroperitoneum, head and neck areas; however, it was named solitary fibrous tumour (SFT) at these locations.⁴ In 2016, the WHO combined SFT and haemangiopericytoma to create the combined term SFT/haemangiopericytoma, as both tumours show a fusion of the NAB2 and STAT6 genes.⁵ Recently, the 2021 WHO classification of tumours of the CNS eliminated the combined term, and the tumour is now named SFT, using Arabic numerals for the tumour grade.⁶ SFT is classified into three grades. Grade 1 refers to highly collagenous, relatively low cellularity, spindle cell lesions; grade 2 includes more cellular, less collagenous tumours with less than five mitoses per 10 high-power fields with plump cells and staghorn vasculature; and grade 3 are lesions with five or more mitoses per 10 high-power fields.^{5 6} To the best of our knowledge, only eight cases of SFT at the craniocervical junction have been reported.^7–14 We presented the ninth case of a craniocervical junction SFT and the first one with a recurrent lesion treated with Gamma Knife radiosurgery (GKRS).

Case presentation

A woman in her early 40s without medical history complained of progressive upper neck and posterior head pain for 3 weeks without improvement after using oral medications. The patient was evaluated at the outpatient clinic and complained of significant right-sided occipital neuralgia. She had no motor weakness, no paraesthesias, no cranial nerve palsies, a negative Romberg test and normal deep tendon reflexes. An MRI of the brain showed a contrast-enhancing posterolateral intradural-extramedullary lesion at the craniocervical junction measuring 2.5 × 2.1 × 2.3 cm (tumour volume 6 cm³), extending down to C2 compressing the medulla and spinal cord (figure 1). Using brain and spinal intraoperative neuromonitoring, the patient underwent a suboccipital craniectomy, C1-2 laminectomy with complete tumour resection, coagulation of the affected dura and closure with a dural matrix substitute. The patient developed a right spinal accessory nerve palsy postoperatively, producing a 2/5 weakness in shoulder elevation without any other neurological deficit. Her occipital neuralgia resolved, and she was discharged home on the third postoperative day. After physical therapy, the patient regained total shoulder elevation 3 weeks later.

Figure 1.

Initial MRI of the brain shows a right posterolateral intradural-extramedullary contrast-enhancing lesion at the craniocervical junction with medullary compression (white arrow). (A) Sagittal T1-weighted gadolinium-enhanced image; (B) axial T1-weighted gadolinium-enhanced image.

Microscopic pathological examination showed a spindle cell lesion with prominent staghorn vessels. Immunostains were positive for CD34, Bcl-2, CD99 and vimentin, and negative for pankeratin, actin, desmin, chromogranin, EMA, S-100, CD56 and GFAP. The Ki-67 proliferation index was 20%, with 15 mitoses per 10 high-power field on the phosphohistone H3 stain. At the time of the original surgery, the diagnosis was reported as a craniocervical haemangiopericytoma, but it was reclassified as an SFT grade 3 according to 2021 WHO classification of tumours of the CNS (figure 2).

Figure 2.

(A) Photomicrograph of the pathological specimen shows a uniform cellular spindle cell lesion with branching blood vessels in the central area (H&E 40×); (B) higher magnification of the solitary fibrous tumour highlighting spindle cells around the vessels (H&E 400×); (C) immunohistochemistry stain with diffuse positivity for CD34 and highlighted vascularity (200×); (D) Ki-67 immunohistochemistry with a proliferation index of 20% (200×).

She was recommended to receive adjuvant radiotherapy due to the high mitotic index; however, she refused. The patient was followed in the outpatient clinic with a yearly MRI of the brain without evidence of tumour recurrence. Eight years after the surgical resection, she developed bilateral upper extremity paraesthesias associated with neck pain.

Investigations

An MRI of the brain showed tumour recurrence with a left-sided ventral intradural-extramedullary lesion at the craniocervical junction measuring 2.8 × 1.8 × 3.5 cm (tumour volume 8.8 cm³) and other small dural-based posterior fossa tandem contrast-enhancing lesions (figure 3). A smaller separate anterior dural lesion at C2-3 and another small suprasellar lesion were also identified.

Figure 3.

An MRI of the brain 8 years later shows the contrast-enhancing recurrent lesion at the craniocervical junction. (A) Sagittal T1-weighted gadolinium-enhanced views show the ventral intradural-extramedullary contrast-enhancing lesion (white arrow), one of the cerebellar extra-axial tandem lesions, a small C2-3 contrast-enhancing dural-based lesion and a suprasellar lesion; (B) axial T1-weighted gadolinium-enhanced views show a left-sided ventral intradural-extramedullary contrast-enhancing lesion at the craniocervical junction with cord compression (white arrow).

Treatment

The larger craniovertebral junction lesion was located at the original tumour site; thus, a biopsy was not considered as these tumours have a great propensity to recur. During the first surgery, the dural attachment was coagulated but not resected, increasing the risk of recurrence. Additionally, the patient did not want a reoperation. Radiosurgery was offered to the patient due to the encasement of the vertebral artery and the additional lesions. The patient received GKRS treatment to the craniocervical junction and the posterior fossa tandem lesions during a single session without complications. The margin and maximum doses delivered were 16 Gy and 32 Gy, respectively, with a median prescription isodose line of 50%.

Outcome and follow-up

The patient’s neck pain and upper extremity paraesthesias improved. Five months after receiving the GKRS, an MRI of the brain showed a reduction in the size of the craniocervical junction lesion, measuring 2.1 × 0.9 × 2.9 cm (tumour volume 2.7 cm³), with decreased mass effect on the adjacent brainstem (figure 4). There was also a reduction in the size of the tandem extra-axial posterior fossa lesions but an interval increase in the size of the C2-3 intradural-extramedullary lesion and the suprasellar lesion. The C2-3 intradural-extramedullary lesion was surgically removed 2 months later without complications. The pathological diagnosis was consistent with an SFT grade 3, similar to the tumour removed 8 years prior. Twelve months after the GKRS, a new MRI of the brain showed further reduction in the size of the craniocervical junction lesion, now measuring 1.8 × 0.7 × 1.7 cm (tumour volume 1.1 cm³) with no mass effect on the adjacent brainstem; however, the suprasellar lesion showed further enlargement and was later treated with GKRS without complications (figure 5).

Figure 4.

An MRI of the brain T1-weighted gadolinium-enhanced views 5 months after Gamma Knife radiosurgery shows the reduction in the left intradural-extramedullary contrast-enhancing lesion at the craniocervical junction (white arrow) with an increased size of the suprasellar lesion (bent white arrow). (A) Sagittal; (B) axial.

Figure 5.

An MRI of the brain T1-weighted gadolinium-enhanced views 12 months after Gamma Knife radiosurgery shows additional tumour reduction (white arrow) but enlargement of the suprasellar lesion (bent white arrow). (A) Sagittal; (B) axial.

Discussion

Intraspinal SFT is a rare extra-axial tumour with a strong tendency to recur and metastasise.³ Liu et al reviewed 26 spinal cases and further characterised them into types I-III depending on their morphology and localisation as extradural, intradural or intra-extradural paravertebral type.³ Surgery is the primary mode of treatment for spinal SFT, with gross total resection recommended when possible.¹⁴ Prognosis is usually favourable if gross total resection can be accomplished. Several studies have reported that the pathological grade is the only significant factor associated with recurrence and survival time; therefore, a maximal safe resection is ideal.^{3 15} The 1-year Kaplan-Meier survival rate for spinal cases is 96%–100% and the 5-year rate is 76%–77%, with a recurrence-free rate of 30%.^{3 15} Betchen et al reported that extradural tumours recurred earlier than intradural tumours (2.6 years vs 6 years, respectively).¹⁶ The recurrence-free period for our patient who had an intradural SFT was slightly longer.

Only eight craniocervical junction SFT cases have been previously reported in the literature (table 1).^7–14 Most authors have reported adequate resections with good outcomes using the suboccipital craniectomy, similar to our approach.7–10 13 14 Arai et al used a transcondylar far-lateral approach advocating a wider surgical corridor, improved haemostasis and excellent outcome.¹¹ SFT is highly vascularised; thus, for a ventral craniocervical junction lesion, a strategic surgical plan must be designed to localise its feeders and maximise the surgical exposure for adequate resection, avoiding brainstem retraction and direct visualisation of its dural attachments.^{17 18} Preoperative embolisation of the tumour has been recommended in some cases to prevent significant intraoperative bleeding and maximise resection, especially when an ‘en bloc’ resection is not possible.^{19 20} Lee et al reported on a patient with a craniocervical SFT in which they had to use intraoperative endovascular embolisation after experiencing uncontrolled haemorrhage.⁹ Embolisation provides an additional alternative to treat these tumours, providing good outcomes and an improved extent of resection.

Table 1.

Craniocervical junction solitary fibrous tumours reported in the literature

Author	Age	Sex	Presentation	Treatment	Resection	Recurrence
Brunori et al7	18	M	Left limb paraesthesia, urinary retention and weakness in upper limbs	Suboccipital craniectomy with C1-2 laminectomies	Total	None at 12 months
Drazin et al8	56	M	Headaches and neck pain radiating to both shoulders	Suboccipital craniectomy with C1-4 laminectomies	Gross total resection	None at 5 years
Lee et al9	21	M	Neck pain and tingling in both hands	Suboccipital craniectomy, C1-2 hemilaminectomy and intraoperative endovascular embolisation	Gross total resection	None at 12 months
Hernandez et al10	23	F	Vomiting, headaches, obtunded, hydrocephalus and left VI cranial nerve palsy	Ventriculoperitoneal shunt, endoscopic third ventriculostomy and suboccipital craniotomy	Partial resection	No follow-up
Arai et al11	38	M	Neck pain, headaches, nausea, bilateral shoulder and hand paraesthesias	Far-lateral transcondylar approach and suboccipital craniotomy	Gross total resection	None at 10 months
Kweh et al12	38	M	Not reported	Surgical resection	Not reported	Yes, at 12 years and 5 years later
Yamaguchi et al13	55	F	Bilateral upper limb numbness, gait disturbance and weakness all extremities	Suboccipital craniectomy, cervical laminectomy and Cyber Knife to the residual lesion (25 Gy/5 fractions)	Subtotal with small residual	None at 6 months
Nishii et al14	68	F	Numbness in right upper limb	Suboccipital craniectomy with C1-3 laminectomies	Subtotal (almost complete)	None at 18 months
Current case	41	F	Neck pain	Suboccipital craniectomy, C1-2 laminectomy, Gamma Knife radiosurgery to the recurrent lesion	Gross total resection	Yes, at 8 years

Radiotherapy has been recommended for cases with subtotal resection, aggressive phenotype and recurrent cases where a repeat surgery was contraindicated.^21–23 Even in patients with complete resection, adjuvant radiation has been shown to improve survival.²⁴ GKRS has been used for intracranial and spinal SFT as adjuvant therapy for residual or recurrent tumours with reasonable tumour control rates.^{3 25–27} GKRS to a recurrent SFT at the craniocervical region has not been previously used. This case demonstrates that GKRS can be a safe and effective treatment for recurrent SFT located at the craniocervical junction. Recently, some authors have reported shorter recurrence-free survival and overall survival in patients receiving stereotactic radiosurgery before the tumour resection.^{28 29} Therefore, stereotactic radiosurgery is recommended for residual and recurrent tumours. Antiangiogenics agents have been recently used with optimistic results.³⁰

Learning points.

• Craniocervical junction solitary fibrous tumour (SFT) is a rare tumour that can recur and spread with high frequency.

• Recurrent craniocervical junction SFT can be treated with Gamma Knife radiosurgery (GKRS) with a significant volume reduction of the lesion.

• GKRS can be a safe and effective treatment for recurrent SFT located at the craniocervical junction.

Ethics statements

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