Giant cell tumor of the sacrum

Abstract

Giant cell tumor of the sacrum is a rare primary tumor in a challenging anatomical location without clear consensus on treatment. We present a case of giant cell tumor of the sacrum and subsequent treatment with preoperative embolization, L5 to S4 laminectomy, partial sacrectomy, intraoperative thermal ablation, and L4 to pelvis stabilization and fusion.

Giant cell tumor (GCT) of the bone is a primary intramedullary bone tumor that comprises 5% of primary bone tumors, with sacral tumors accounting for 2% to 8% of GCT.^1,2 GCT is considered a locally aggressive, intermediate-grade benign bone tumor with rare cases of malignant degeneration and systemic metastasis.³ Most commonly, it occurs in the metaphysis, with extension to the epiphysis in most skeletally mature patients.^3,4 In all locations, it occurs commonly in patients between the age of 20 and 45 years and has no gender predilection.² Patients with GCT of the sacrum may present with a history of progressive lower back pain, lower extremity pain with point tenderness, and palpable masses on physical exam.⁵ Symptoms may include pain, saddle anesthesia, and neurologic deficits in sacral nerve distributions.^2,5 There is a paucity of literature describing this neoplasm and a lack of consensus for the management of GCT of the sacrum. The anatomical location and close relation of the tumor to nerve roots pose challenges for surgical resection. This article describes one method of treatment used for GCT of the sacrum, with discussion of other relevant surgical treatment options.

CASE DESCRIPTION

A 56-year-old woman was referred to the orthopedic spine clinic after 3 months of worsening low back pain, with radicular pain and numbness radiating down her legs—the right greater than the left. She denied bowel and bladder incontinence, fever or chills, weight loss, weight gain, night sweats, or a history of cancer. On physical examination she had no objective motor deficit, had decreased sensation to pinprick in her distal lower extremities, and had decreased S1 reflex with positive bilateral straight leg raise sign.

Magnetic resonance imaging (MRI) and computed tomography (CT) (Figure 1) revealed a lytic, destructive sacral mass centered at S2 to S4. MRI demonstrated an 8.1 × 8.7 × 3.2 cm multilobulated destructive mass involving the S2 to S4 vertebral bodies causing severe canal stenosis, with evidence of presacral extension and invasion in the right piriformis muscle. Metastatic workup was negative. A CT-guided core biopsy confirmed the diagnosis of GCT. Surgical options discussed with the patient included en bloc resection with reconstruction vs intralesional resection, partial sacrectomy, argon beam thermal ablation, and lumbopelvic fixation. The patient had additional consultations with orthopedic oncology, hematology/oncology, and radiation oncology. After a multidisciplinary discussion of pros and cons and risks and benefits, the patient elected to proceed with the latter surgical option. She subsequently underwent preoperative tumor embolization.

Figure 1.

Patient imaging. T2 weighted MRI, (a) sagittal and (b) axial views, revealing a large, expansile, multilobulated tumor of the sacrum with presacral extension. CT, (c) sagittal and (d) axial, demonstrating large, lytic, expansile destructive mass involving the sacrum.

L5 to S4 laminectomy and lumbopelvic stabilization with spine fusion were performed from L4 to the pelvis (Figure 2). A bone graft was placed in the posterolateral gutters to perform an L4–S1 fusion. After completing a wide laminectomy, intralesional resection of the tumor was performed around the thecal sac with preservation of the sacral nerve roots. A partial sacrectomy was performed to resect gross disease. Orthopedic oncology then performed additional curettage, pulse lavage, and thermal ablation of the cavity. A high-speed burr was used to decorticate the end ostium and remove macroscopic tumor tissue. The treatment was augmented with ablation using argon beam coagulation in order to treat the surfaces of the residual sacrum.

Figure 2.

(a) Tumor resection. (b) Completed laminectomy, partial sacrectomy, and spinal instrumentation with visualization of decompressed sacral nerve roots.

Postoperatively, the patient had no neurological deficits in her lower extremities with preservation of bowel and bladder function. She was discharged home after clearing physical therapy. At 3-week, 6-week, and 3-month follow-up, she continued to improve significantly, with no low back pain or radicular symptoms. She maintains full strength and sensation in her lower extremities, with x-rays showing no signs of hardware complications (Figure 3). Plans have been made for continued follow-up with spine surgery and hematology/oncology for surveillance and monitoring for local recurrence and systemic disease.

Figure 3.

Three-month follow-up anteroposterior radiograph of the pelvis revealing postoperative decompression and lumbopelvic posterior instrumentation with posterior intrapedicular screw and rod fixation from L4 to S1.

DISCUSSION

Patients commonly present with local tenderness at the site of the tumor.⁴ Our patient’s history of worsening back pain with lower extremity radiculopathy is consistent with documented cases in the literature. Patients also commonly present with focal neurological deficits such as bowel/bladder incontinence, weakness, numbness, or paresthesia.² Upon diagnosis, GCTs often have extended to nerve roots and are very vascular.³ Our patient presented with low back and radicular pain but without focal neurological deficits. The tumor involved the spinal canal and sacral nerve roots with extension into the presacral region and invasion into the piriformis.

There is no clear consensus on the treatment of GCT in the sacrum due to its rarity and the difficult anatomical location, requiring case-by-case management.^3,6 The sacrum is reportedly the most common location for a spinal GCT.⁷ Available treatment options include denosumab, serial embolization, interferon, radiation therapy (such as proton beam therapy and external beam irradiation), and intralesional curettage or wide resection.⁶ Intralesional curettage utilizes a burr and pulse lavage to reduce targeted bone. Wide resection (en bloc) is removal of a tumor and a margin of healthy surrounding tissue to ensure total excision.⁸ Wide resection has decreased local recurrence but increased morbidities such as infection and nerve injury.⁶ Obtaining a wide resection in this anatomical location is challenging, is more invasive, can require a multistage operation and diverting colostomy, and sacrifices the sacral nerve roots. Surgical intervention via either intralesional curettage or wide resection of locally resectable tumors is considered optimal.⁶ Other adjuvant therapies have been used in conjunction with extended curettage for GCT. These include phenol, liquid nitrogen, and thermoablation. However, argon beam laser coagulation provides a higher level of accuracy with respect to vital anatomical structures—particularly important given the proximity of disease to the dura mater and exiting nerve roots.⁹ In 2010, Thangaraj et al proposed a treatment algorithm that matches the treatment of our patient.¹⁰ Their algorithm starts with embolization preoperatively, followed by resection of small distal tumors and finally curettage of tumors. Though nonsurgical management with denosumab may be appropriate in select cases, we did not feel this was appropriate in our patient.^11,12

Ultimately, after thorough discussions, our patient opted for a plan that would attempt to definitively address the tumor, improve her pain, preserve function, and minimize permanent neurological deficits. She will also undergo additional postoperative adjunct treatment with external beam radiation with close surveillance for local recurrence. She will need long-term surveillance, as recurrence rates of GCT have been reported to be as high as 50% if a form of treatment other than en bloc resection is performed.¹³ In addition, due to the known incidence of pulmonary metastasis, the patient had preoperative staging studies including a chest CT and will be followed by oncology with routine monitoring to identify pulmonary involvement. This case report demonstrates a multidisciplinary approach for surgical management of GCT of the sacrum.