Advancing Preoperative Diagnosis: Case Report and Imaging Analysis of Cervical Spine Tenosynovial Giant Cell Tumor

Introduction

Tenosynovial giant cell tumor (TGCT) is a rare, benign, but locally aggressive, disease that develops in the synovia of joints, bursa, or the tendon sheath [1]. According to growth patterns and biological behavior, TGCT can be categorized into localized type or diffuse type [2]. The diffuse type commonly involves weight-bearing joints like the knees, ankles, and hips, with the possibility of invasion. In contrast, the localized type usually presents as a solitary, well-defined mass next to tendons or small joints such as hand and wrist. Involvement of the spine is quite rare. Since the first localized-type case was reported in 2002 by Dingle [2], only 34 cases have been published [1–13]. Thus, pre-operative diagnosis is very challenging. Typically, spinal TGCT is located close to the adjacent facet joint, with widening of the facet joint, suggesting an origin in the synovial tissue, and presents with a characteristic low-intensity signal on T2-weighted images due to hemosiderin deposition [14]. However, when encountering an atypical bone-centered lesion, as illustrated in our case, its low-intensity signal and lytic radiographic appearance could mimic other benign and malignant diseases, including giant cell tumor of bone, metastatic disease, and osteoblastoma [14], thus posing a diagnostic dilemma. In this report, we provide a new case of localized TGCT concentered in the C5-6 right vertebral lamina and spinal process, resulting in an expansive, destructive lesion, and we describe its computed tomography (CT) and magnetic resonance imaging (MRI) findings to enhance awareness and improve accurate preoperative diagnosis.

Case Report

CLINICAL HISTORY:

A 33-year-old man experienced neck pain of level 2 on the numeric rating scale (NRS), radiating to the right upper limb for over 1 year, then it started to progress for 1 month, to a level of NRS=5. There was no weakness of the lower limbs or limitation in the cervical spine range of motion (ROM). There were no changes in bowel or bladder function. The physical examination revealed modest soreness in the right side of the cervical spine. No masses were palpated. Neurological examination revealed no abnormalities in the upper or lower extremities.

IMAGING:

The CT revealed a 4.97×11.4×2.76 cm osteolytic, expansive, destructive lesion concentered in the C5 right vertebral lamina and spinal process (Figure 1). The C6 spinal process was also affected, and the cortical bone had deteriorated. The lesion was well-defined, and the soft tissue density was uniform. There was no calcification or ossification identified within the mass. MRI demonstrated a lobulated mass located in the C5-6 right vertebral lamina and spinal process. The MRI revealed a heterogeneous isointense lesion on T1- weighted images with low signal relative to muscle on T2-weighted images (Figure 2). Following contrast medium injection, the lesion showed obvious heterogeneous enhancement. A dynamic contrast-enhanced MRI (DCE-MRI) revealed that the time-intensity curve (TIC) was of type II (rapid enhancement with low washout curve).The tumor was located next to the spinal foramen and had obliterated the right lateral recess. The thecal sac was displaced laterally without spinal cord compression. Overall imaging features of the lesion were suggestive of a slow-growing tumor involving posterior elements of the cervical spine, and the possibility of giant cell tumor was a concern. To definitively characterize the lesion, preoperative CT-guided fine needle aspiration and core biopsy were performed. Hematoxylin and eosin preparation slides showed mononuclear cell proliferation with scatted multinucleated giant cells. On the basis of these data, combined with the imaging findings, a preliminary diagnosis of giant cell tumor of bone was made.

TREATMENT:

Given the technical difficulty of surgical resection, to avoid inadvertent injury to adjacent critical structures such as major vessels and nerve roots, preoperative 3D printing of the tumor was performed to assess its intraoperative location and extent. Subsequently, a single-stage combined anterior and posterior en-bloc resection was performed. A C5-C6 laminectomy was performed and the spinal process was totally removed. The mass was fulvous, soft, irregular, and heterogeneous, extending to the right facet joint. The right C5 and C6 roots were anteriorly displaced, and the C5 root was adhesive with adjacent soft tissue. After carefully decompressing the C5 root and right vertebral arteries, the tumor was complete excised. The removed specimen measured roughly 8×6×2.5 cm. Stabilization was achieved by C5-6 interbody fusion and posterior internal fixation (Figure 3).

PATHOLOGICAL FINDINGS:

Histologically, the lesion was composed of spherical histocyte-like cells, numerous multinucleated giant cells, foamy cells, and siderophages with a large amount of hemosiderin. There was no reactive bone or cartilage formation within the tumor. There was no evidence of malignancy. Immunohistochemistry revealed that the giant cell tumor was strongly positive for CD68, CD163, and D2-40. Ki-67 immunostaining demonstrated 10% nuclear proliferation. The final histological diagnosis was suggestive of giant cell tumor of the tendon sheath (Figure 4).

FOLLOW-UP EXAMINATION:

The patient’s neck pain and forearm numbness improved considerably. There was no sign of a recurrence on the CT and MRI during the 2-year follow-up.

Discussion

In the present study, we describe a new case of bone-centered, spinal, localized TGCT, and offer a thorough review, focusing on imaging findings and diagnostic considerations. Spinal TGCT should be considered when an osteolytic lesion involving the posterior elements of the vertebral facet joints appears with low signal intensity on T2-weighted image and with a type II TIC.

To the best of our knowledge, only 34 cases of localized TGCT have been reported. These cases can be found in 19 reports, from January 2002 to April 2024. They included 20 women and 14 men, and the mean age at onset was 34.25 years (range: 9-65 years). The most common symptom was pain (55.89%), followed by neurological symptoms. Among them, 73.52% of the cases (25/34) affected the cervical spine. The symptoms in our case were consistent with previous reports on spinal TGCT.

Due to its rarity and due to having similar clinical and imaging features with other benign and malignant diseases, the definitive preoperative diagnosis of spinal TGCT poses a clinical challenge in daily practice. Advanced imaging modalities such as CT and MRI are highly valuable in defining the nature of the lesion and narrowing the list of the differential diagnoses. According to our literature review, 84.37% of cases (27/32) showed osteolytic bone destruction with formation of sclerosis rim or soft mass with bone erosion; only 5 cases displayed soft tissue without bone change (Table 1). Most TGCT lesions involve the posterior components of the spine with a hyper-density soft tissue tumor, which may be associated with hemosiderin accumulation [15]. The presence of calcification or matrix mineralization is uncommon. Spinal TGCT is thought to originate from the facet joint synovial lining and usually is associated with widening of the facet joint [16]. However, our case showed a bone-centered lesion with expansile bone destruction and without evidence of widening of the facet joint. This suggests that these unconventional sites could result in diagnostic difficulty.

MRI is especially important for recognizing the origin of the lesion as synovial in nature. Case reports found that 57.58% of cases (19/33) appeared as isointense on T1-weighted images, and 69.7% of cases (23/33) appeared as hypointense on T2-weighted images. The low signal intensity in T2-weighted images and blooming artifacts on MRI are thought to be characteristic features of TGCT [17]. In our case, the lesion appeared with low signal relative to muscle on T2- weighted images, which was similar to previously reported findings. It was worth noting that the T2-weighted low signal intensity was affected by the amount of hemosiderin [18]. In our case, a large amount of hemosiderin deposition was also demonstrated on histological analysis. As a different approach from conventional contrast enhancement, we performed the dynamic contrast-enhanced MRI (DCE-MRI). Another result was a type II TIC (rapid enhancement with low washout curve). This finding may have been associated with increased capillary permeability due to thickened synovial inflammatory pathology [19].

Considering our case was of a bone-centered lesion, primary bone lesions such as aneurysmal bone cysts (ABCs), giant cell tumors of bone, osteoblastoma, and metastases should be included in differential diagnosis, due to their similar low signal intensity and lytic radiographic appearance. ABCs and osteoblastoma both show a predilection for the posterior vertebral elements. ABCs classically present as multiple expansile cystic lesions with variable signal intensity on T1- and T2-weighted images. If there is presence of fluid-fluid levels, it is more likely that the lesion may be an ABC. Osteoblastoma usually shows calcification or matrix mineralization within the tumor, and hyperintensity with extensive marrow edema on T2-weighted images. Giant cell tumors of bone show involvement of the vertebral body more than the posterior element, with variable findings on T2-weighted images. However, the ultrastructural cytochemical features of multinucleated giant cells and mononuclear stromal cells have similarities [20]. Metastatic tumors should be considered when malignant tumors have already occurred, or when there is involvement of the posterior vertebral body or spinal attachments, particularly in elderly patients. Regarding our case, the lesion concentered in the C5 right vertebral lamina and spinal process made definitive diagnosis difficult on the basis of imaging features.

Currently, the nature of spinal TGCT is still obscure. Reaction to chronic inflammation, metabolic disequilibrium, and trauma have been considered as possible etiological factors [21]. Chromosomal aberrations such as trisomy 5, trisomy 7, and monoclonalities have also been associated with the development of spinal TGCT [16]. Overexpression of colony-stimulating factor-1 (CSF-1), caused by translocation from chromosome 1p13 to 2q25, is considered characteristic of-- and diagnostic of-- TGCT. In our case, immunohistochemistry showed positive results for CD68 and CD168, indicating that the majority of reacting cells were monocytes.

Gross total resection (GTR) is the recommended course of action because of the local aggressive nature of this tumor, with a high risk of recurrence [11]. GTR, however, is risky for neurovascular damage and is technically difficult. In our case, preoperative 3D printing of the tumor was conducted before surgery to assess the intraoperative location and extent of the tumor, which can serve to avoid inadvertent injury to adjacent major vessels and nerve roots. In cases in which complete resection cannot be performed, subtotal resection combined with radiation should be considered due to the high recurrence rate (66.7%) [13]. Recently, targeted therapy has gained momentum. Pexidartinib, a CSF-1 receptor inhibitor, has been utilized to treat recurrent or incurable TGCT [17]. It has been demonstrated to diminish tumor size, symptoms, and improve functional performance in patients [17].

Conclusions

Bone-centered spinal TGCT can be misdiagnosed as a different type of benign or primary malignant tumor. It is important to raise the awareness of TGCT as an important differential diagnosis. When an osteolytic lesion involving the posterior elements of vertebral facet joints shows low signal intensity on T2-weighted imaging and type II TIC, the possibility of spinal TGCT should be considered.