Giant cell tumor of the temporal bone: two case reports and literature review

Khansa Abderrahmen; Khalil Ghedira; Alia Zehani; Skander Kedous; Sofiene Bouali

doi:10.7181/acfs.2025.0026

Abstract

Giant cell tumor (GCT) of bone is a benign tumor originating from undifferentiated mesenchymal cells of the bone marrow. It most commonly arises in the epiphyseal regions of long bones. The skull represents an extremely rare location for GCT. Certain radiologic features involving the temporal or sphenoid bone strongly suggest this diagnosis. Skull GCT is a locally aggressive condition, posing surgical challenges and exposing the patient to a considerable risk of recurrence. In this article, we describe the diagnosis and surgical management of two patients with GCT of the temporal bone. The first patient is a 24-year-old man who presented with progressive left temporal swelling and hearing loss. Computed tomography revealed a 5.6× 4.6× 4.2 cm osteolytic lesion of the left temporal bone. The patient underwent neartotal resection and exhibited no recurrence after 10 years of follow-up. The second patient was a 55-year-old man presenting with gradual hearing loss in the right ear and trismus. Computed tomography showed a 4.7× 4.2× 3 cm temporo-sphenoidal erosive lesion. Complete surgical resection was performed with a favorable outcome and no recurrence.

Keywords: Case reports / Craniotomy / Giant cell tumors / Skull base / Temporal bone

Abbreviations

computed tomography

ENT

ear, nose, and throat

GCT

giant cell tumor

MRI

magnetic resonance imaging

INTRODUCTION

Giant cell tumor (GCT) of bone is a rare primary neoplasm that accounts for approximately 5% of all primary bone tumors [1]. It predominantly affects adults in their second to fifth decades of life, with a slight female predominance, and frequently occurs in the metaphyses or epiphyses of long bones after skeletal maturation [2-4]. GCT of the skull is extremely rare; when it does occur, the temporal bone is among the most frequently affected sites [4,5]. Clinical manifestations include pain, swelling, facial paresis, and hearing loss. Although GCT is a benign bone tumor, it is characterized by local aggressiveness, invasion of neighboring structures, and a high tendency for recurrence following removal. Complete surgical resection is considered the gold standard treatment, while the role of adjuvant therapies remains debated. Given the rarity of this condition, we present two cases of GCT of the lateral skull base involving primarily the temporal bone. We describe the associated clinical and radiological findings, as well as the surgical management and outcomes.

CASE REPORTS

Case 1

The first patient, a 24-year-old man, presented to our neurosurgery department in 2010 with a painless swelling in the right temporal region that had been slowly growing over 3 years. For the last 5 months, he had experienced a sensation of fullness in the right ear along with hearing impairment. His family history revealed that his father had died of leukemia at 65 years old, while his mother had died of kidney cancer at the age of 55. Physical examination revealed a well-defined mass measuring 4×3 cm in the right temporal region. It was firm, painless, and fixed to the underlying bone, and the overlying skin appeared normal. No cervical lymphadenopathy was palpable. Neurological examination was unremarkable except for moderate conductive hearing loss in the right ear. Computed tomography (CT) demonstrated a well-defined 5.6×4.6×4.2 cm osteolytic expansile lesion centered within the diploe of the squamous part of the temporal bone, altering the outer and inner tables of the skull (Fig. 1A). The tumor exhibited heterogeneous and moderate contrast enhancement, reaching the temporomandibular joint. On magnetic resonance imaging (MRI), the lesion displayed heterogeneous signals: isointensity and hypointensity on T1-weighted images and hypointensity and hyperintensity on T2-weighted images (Fig. 1C), with heterogeneous enhancement following intravenous gadolinium administration (Fig. 1B). The lesion had caused destruction of the right lateral skull base and extended to the ipsilateral carotid canal and foramen ovale. Surgical treatment was proposed, but the patient initially refused intervention and was lost to follow-up. Four years later, he was readmitted due to worsening hearing impairment in the right ear. A CT scan indicated slight progression of the osteolytic lesion. Following patient consent, surgery was performed collaboratively by the neurosurgery and oncologic ear, nose, and throat (ENT) teams. Through a C-shaped preauricular skin incision and an infratemporal fossa approach with the patient in the lateral position, surgeons encountered a grayish, soft, and well-demarcated mass involving the squamous portion of the temporal bone, the temporal fossa, the greater wing of the sphenoid bone, and the zygoma. The tumor contained hemorrhagic foci surrounded by an eggshell-like layer. Near-total tumor resection was achieved, followed by cranioplasty to reconstruct the bone defect. Histopathological examination confirmed the diagnosis of GCT. Immediately postoperatively, the patient exhibited right peripheral facial nerve palsy. CT and MRI performed 6 months after surgery confirmed near-total tumor resection (Fig. 1D). At 10 years after surgery, the patient remains disease-free with no clinical signs of recurrence. His facial paresis has improved with rehabilitation therapy.

Case 2

The second patient was a 55-year-old man who presented with gradual hearing loss in the right ear for 4 months, accompanied by tinnitus and dizziness. Over the prior 10 days, he had experienced progressive trismus. Physical examination revealed temporomandibular disorder with significant atrophy of the right temporalis muscle, positive Romberg sign, and severe right-sided conductive hearing loss. An emergent non-contrast CT scan showed a well-defined heterogeneous mass arising from the squamous part of the temporal bone, eroding the greater wing of the sphenoid and part of the middle fossa. Subsequent MRI revealed a well-demarcated extra-axial heterogeneous expansive lesion in the right middle cranial fossa on T1- and T2-weighted sequences. The mass measured 4.7×4.2×3 cm and demonstrated mild enhancement following gadolinium administration (Fig. 2A). With the patient’s consent, the lesion was surgically addressed via a C-shaped preauricular infratemporal fossa approach by a collaborative team of neurosurgery and oncologic ENT specialists. Marked hypotrophy of the temporalis muscle enabled wide exposure of the well-circumscribed yellowish tumor arising from the temporal bone. Complete surgical removal of the lesion was achieved, and the postoperative course was uneventful. Histopathological analysis revealed multinucleated osteoclastic giant cells within a back-ground of neoplastic mononuclear stromal cells (Fig. 3), findings consistent with GCT. A brain CT scan performed 1 month after surgery confirmed complete tumor resection (Fig. 2B). The patient remained disease-free at the 6-month follow-up.

LITERATURE REVIEW

GCTs of bone are osteolytic neoplasms first described in 1818 by British surgeons [6]. They were later characterized in 1940 by American pathologists [7]. These lesions, considered benign tumors, are derived from non-osteogenic stromal cells of the bone marrow within endochondral bone. They typically arise in the epiphyses of long bones, commonly the distal radius and femur, as well as the proximal tibia and fibula. Only 1% to 2% of all GCTs occur in the cranium, predominantly at the lateral skull base [1,8]. Feng et al. [4] conducted a structured literature review of PubMed/MEDLINE between 1970 and 2017 and identified only 94 cases of GCT involving the lateral skull base. More recently, in 2018, Kaya et al. [1] reviewed 110 cases of GCT originating in the skull. The authors concluded that these tumors were most frequently centered in the temporal bone (in 37 patients), followed by the sphenoid bone (20 patients). GCT likely exhibits a predilection for these regions because the sphenoid and temporal bones develop predominantly through endochondral ossification, while other skull bones form via intramembranous ossification [8].

Patients typically present with auditory symptoms such as conductive hearing loss, tinnitus, vertigo, aural fullness, otalgia, facial weakness or hypoesthesia, and headache [1,4,8]. Localized swelling in the temporal or preauricular region is another common initial symptom [4,8]. Classically, the swelling is firm, painless, and immobile, with healthy overlying skin. Other clinical features include visual dysfunction or temporomandibular joint disorders when the tumor involves the sphenoid bone or mandibular joint fossa, respectively [1,8,9].

A complete radiological assessment using both CT and MRI is essential for the diagnosis and surgical planning of GCTs of the lateral skull base. CT scans are superior to MRI for delineating the extent of bone invasion by the tumor. On CT imaging, GCT of the temporal bone typically appears as a mixed-density mass, often originating from the petromastoid region of the temporal bone [1,4]. Craniocaudal and lateral views from three-dimensional CT scans provide a more precise anatomical depiction of bone destruction in the middle cranial fossa and possible extension into the greater wing of the sphenoid, zygoma, or mastoid. Most GCTs are contrast-enhancing lesions [1]. In some cases, CT images display a soap-bubble appearance more characteristic of aneurysmal bone cysts [1]. MRI is preferred for assessing lesion texture and relationships with adjacent neurovascular structures. Typically, GCTs exhibit heterogeneous isointense and hypointense signals on T1-weighted images and hypointense and hyperintense signals on T2-weighted and diffusion images, with heterogeneous enhancement following intravenous gadolinium administration [1,5,8]. Low-intensity signals on T1- and T2-weighted images may reflect hemosiderin deposition, which is characteristic of GCT [10]. These masses are usually well-circumscribed and compress adjacent brain structures [11].

Surgical resection is the only effective treatment for patients with temporal bone GCTs. The aim of surgery is to maximize the extent of resection while preserving the anatomical and functional integrity of the surrounding neurovascular structures. The anatomical and functional complexity of the temporal bone makes complete tumor resection challenging, and surgery may lead to severe morbidity [4,5,8,10]. Moreover, GCTs are known for their local aggressiveness. The tumor may extend beyond the temporal bone, destroying the middle fossa and involving the intracranial space, infratemporal fossa, pterygopalatine fossa, or parapharyngeal space, thus making total resection less feasible [10]. Analyzing both MRI and three-dimensional CT images is crucial for accurately evaluating the tumor’s intracranial and extracranial extensions, selecting an optimal surgical approach, and determining the feasibility of complete resection. Middle cranial fossa and infratemporal fossa approaches are commonly used for tumor removal [1,4,8,10]. It is imperative to protect the critical neurovascular structures surrounding the tumor. Most reported cases with skull base destruction are reconstructed using a temporalis muscle flap [4,10]. Other reconstruction options for the bone defect include artificial patches, titanium mesh, or autologous fat [10,11].

Histopathological examination is used to confirm the diagnosis of GCT, which exhibits characteristic features. Tumor proliferation consists of sheets of stromal mononuclear spindle cells containing uniformly distributed multinucleated osteoclastic giant cells [8,5]. No atypical mitosis is observed [5], although a mitotic count of ≥10/mm2 has been correlated with aggressive forms of GCT [12]. Despite its benign nature, GCT can exhibit aggressive behavior with a tendency to recur, and in rare cases it may undergo sarcomatous transformation with possible metastasis [1,5,8]. The recurrence rate depends on the adequacy of surgical excision. Kaya et al. [1] reported a recurrence rate of 27% for cases treated solely with intralesional surgical approaches. After radical excision, the recurrence rate drops to 8% [9]. Recurrent tumors carry a higher risk of malignancy than primary GCTs [9].

Achieving “safe” total surgical resection can be difficult due to the tumor’s proximity to critical neurovascular structures. Adjuvant radiotherapy and denosumab may be reasonable alternatives in such cases. However, their use remains a topic of debate [1,2,9].

DISCUSSION

Both patients reported in this article are male. A literature review suggests an almost equal distribution of GCT between sexes, with a female-to-male ratio ranging from 1:1 to 1.5:1 [4,13]. Our patients were 24 years old and 55 years old, corresponding to the most frequently affected age range for this disease: between the second and fifth decades of life. In our first case, a family history of malignancies was reported, although exact histological diagnoses were unknown. GCT is associated with mutations in the histone H3.3 protein, particularly the H3F3A p.G34W mutation. Other malignancies correlated with H3.3 mutations include chondroblastoma and pediatric glioma. Immunohistochemical testing for the H3F3A G34W mutation may be useful in distinguishing GCT from diagnoses such as chondroblastoma, non-ossifying fibroma, giant cell reparative granuloma, primary aneurysmal bone cyst, and giant cell-rich osteosarcoma [14].

Both patients in this series presented with hearing symptoms. The first case was associated with swelling in the temporomandibular region, while the second included vestibular signs. A 2018 literature review by Gamboa et al. [15] concerning 94 patients indicated that clinical presentations included headache (33%), hearing loss (31%), facial or periauricular swelling (22%), facial or periauricular pain (17%), tinnitus (15%), aural fullness (10%), diplopia (10%), vision loss (10%), ear pain (8%), facial nerve palsy (8%), proptosis (5%), and dizziness (5%).

In GCT, multinucleated osteoclastic giant cells are activated by mononuclear neoplastic cells through the binding of the RANKL (receptor activator of nuclear factor kappa B ligand), expressed by neoplastic cells, to its receptor (RANK), present on the surface of osteoclastic cells. This phenomenon leads to increased bone absorption [14]. GCT of bone is characterized by an osteolytic appearance on CT, manifesting as soft tissue masses that expand into and destroy the bone without invading the cerebral cortex [13]. MRI classically shows a heterogeneous, well-delineated mass with hypointense to isointense signals on T1-weighted images, isointense to hyperintense signals on T2-weighted images, and enhancement following gadolinium administration [13]. These typical radiological findings were present in our two cases.

We achieved total resection in one of our two patients (Case 2), which represents the preferred treatment option for GCT of bone. The patient remains under close clinical and radiological follow-up due to the known risk of recurrence even after radical resection. In Case 1, the patient remained recurrence-free during 10 years of follow-up, despite undergoing near-total resection. He also experienced transient facial nerve palsy in the postoperative period. In GCT of the lateral skull base, the facial nerve is often invaded by the tumor in one or more segments, although preoperative facial paralysis is infrequent [1,8,10,11].

A review of the literature suggests that radiation therapy has been employed for unresectable remnants or recurrence, while targeted therapy with denosumab has been effectively used in inoperable cases or to reduce tumor volume before surgery [4,12,16,17].

In conclusion, we describe two typical cases of GCT of bone in a rare location—the lateral skull base—with long-term follow-up in one patient. Approximately 100 cases have been reported in the English-language literature. For this entity, attention should be given to early detection and early radical resection to achieve favorable outcomes. Close follow-up is recommended due to the potential risk of GCT recurrence.

Notes

Conflict of interest

No potential conflict of interest relevant to this article was reported.

Funding

None.

Ethical approval

The study was approved by the Institutional Review Board of Mongi Ben Hamida National Institute of Neurology (No. CE 2025/21).

Patient consent

The patients provided written informed consent for the publication of the case details and the use of images.

Author contributions

Writing - original draft: Khansa Abderrahmen, Khalil Ghedira, Alia Zehani. Writing - review & editing: Khalil Ghedira, Sofiene Bouali, Skander Kedous. Investigation: Khansa Abderrahmen, Alia Zehani. Supervision: Sofiene Bouali. Validation: Khalil Ghedira, Sofiene Bouali.

Fig. 1.

A 24-year-old man with right temporal swelling and conductive hearing loss. (A) Axial head computed tomography scan in bone window showing an expansive osteolytic mass lesion in the right temporal bone. (B, C) Axial T1-weighted images after gadolinium administration and coronal T2-weighted images demonstrating mixed hypointense and hyperintense signals on T2-weighted images with heterogeneous enhancement. (D) Postoperative coronal T2-weighted image showing near-total resection.

Fig. 2.

A 55-year-old man with right temporomandibular disorder, temporalis muscle atrophy, positive Romberg sign, and severe conductive hearing loss. (A) Preoperative axial T1-weighted magnetic resonance image with gadolinium showing a large, expansive tumor in the temporal fossa with heterogeneous contrast enhancement. (B) Three-dimensional reconstruction of postoperative computed tomography scan at 1 month after surgery, showing gross total resection of the tumor with a large bony defect in the right middle cranial fossa.

Fig. 3.

(A) Tumor proliferation with mild density and diffuse architecture adjacent to aneurysmal vascular changes (hematoxylin and eosin [H&E] stain, ×10). (B) Giant cells of large volume with multiple nuclei, associated with mononuclear cells containing ovoid nuclei (H&E stain, ×40).

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