Benign Fibro-osseous Tumor of The Clivus: A Case Report

Ahmad Aldajani, MBBS, SBORL-HNS, JBORL, FKSU* ^1,2, Fatima S. Alangari, MBBS ¹, Abdulrazag Ajlan, MBBS, FRCSc ³, Abdulaziz S. Alrasheed, MBBS, MSc. FRCSc ¹

1. Department of Otorhinolaryngology Head & Neck Surgery, Faculty of Medicine, King Saud University, Riyadh, Saudi Arabia.

2. Department of Otorhinolaryngology Head & Neck Surgery, Faculty of Medicine, University of Jeddah, Jeddah, Saudi Arabia

3. Division of Neurosurgery, Department of Surgery, College of Medicine, King Saud University, Riyadh, Saudi Arabia.

*Correspondence to: Ahmad Aldajani, Department of Otorhinolaryngology Head & Neck Surgery, College of Medicine, University of Jeddah, Jeddah, Saudi Arabia - Department of Otolaryngology Head & Neck Surgery, College of Medicine, King Saud University, Riyadh, Saudi Arabia

ORCID ID: 0000-0001-8043-9096.

Copyright

© 2024 Ahmad Aldajani,. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Received: 01 March 2024

Published: 16 March 2024

Abstract

Clival lesions are uncommon and can indicate a variety of benign and malignant disorders, with chordoma and chondrosarcoma being the most prevalent with 0.2% and 0.15% respectively of all intracranial tumors and 1-4% and 11% of all bone malignancies. Fibro-osseous lesions are usually caused by fibrous dysplasia, in which medullary bone is replaced by fibro-osseous tissue, causing the afflicted bone to deform and overgrow. We present a case of a benign fibro-osseous tumor of the clivus with radiographic images in a 32-year-old female patient who had a history of on and off headache, with an unremarkable physical examination. Radiological imaging revealed a clival tumor. She underwent an endoscopic transnasal transsphenoidal resection of the clival tumor with frozen section sent intra-operatively. Frozen section showed a benign fibro-osseous lesion demonstrated by a benign low-grade spindle cells lesion and tiny fragment of benign bone, which were consistent with a benign lesion. Histopathological examination and molecular testing supported our diagnosis. In this case, radiographic imaging together with histopathological examination were vital in the diagnosis of fibro-osseous lesions in the clivus. Evaluation and therapy must take a multidisciplinary approach and it is crucial to remember that these patients may develop new symptoms that mask more serious disorders, thus serial follow-ups are essential.

Introduction

A piece of bone at the base of the skull is known as the clivus. A mass involving or arising from the clivus might originate from either the skull base or the intracranial compartments. Clival lesions are uncommon and can indicate a variety of benign and malignant disorders, with chordomas and more or less chondrosarcomas being the most prevalent. They represent approximately 0.2% and 0.15% respectively of all intracranial tumors.[1] Chordomas and chondrosarcomas account for 1-4% and 11% of all bone malignancies respectively, and also, chondrosarcoma accounts for 6% of skull base tumors. [2-3] Metastatic lesions of the clivus are extremely rare representing 0.02% of all intracranial tumors. [4] Fibro-osseous lesions are usually caused by fibrous dysplasia, in which medullary bone is replaced by fibro-osseous tissue, causing the afflicted bone to deform and overgrow. [5-7] The lesion's position truly reflects the tumor's embryological origin in that particular area. In this case, a 32-year-old female patient had a benign fibro-osseous lesion of the clivus.

Case Presentation

This is a case of a 32-year-old female patient, known case of Allergic Rhinitis (AR) for a long time. She was in her usual state of health until six years prior to admission when she started complaining of on/off episodes of posterior headache. The episodes lasted for couple of hours and was described as “electrical sensation-like” and heaviness of the head, and was 6/10 on the pain scale which affected her daily activities. It was relieved temporarily by analgesia and physiotherapy. The pain, which was non-radiating, usually started at the early hours in the morning and was associated with photophobia, neck pain and on/off night sweats. There was no history of nasal obstruction, Rhinorrhea, smell changes, facial pain or pressure. There was also no history of ear pain, ear discharge, vertigo, tinnitus or hearing loss. Furthermore, there was no history of airway distress, hoarseness, stridor, aspiration or dysphagia. The patient denied any history of neurological symptoms including tingling sensation, numbness, paresis, paralysis, change in mental status or behavior, coordination problems, seizures or motor loss. She also denied any history of raised Intracranial pressure (ICP) symptoms such as diplopia, blurred vision, visual loss or changes in vision. No history of radiation exposure or constitutional symptoms such as fever, fatigue, loss of appetite or weight loss where mentioned. Meanwhile, her Family history revealed that her uncle died from abdominal cancer. Lastly, her past surgical and social history were negative.

On clinical examination, Neurological examination including motor, sensory and cerebellar examination were normal. Vision and eye movements were normal. Head and neck examination including lymph node examination was negative and did not reveal any palpable LN. Ear examination was normal and showed an intact tympanic membrane bilaterally. However, her nasal examination showed a deviated nasal septum to the right with hypertrophied inferior turbinates bilaterally. Throat examination was normal.

MRI brain was done and showed a Clival lesion with its epicenter of midline to the right, measuring 25x29x15 mm in transverse, antrum posterior and craniocaudal dimensions respectively. It shows heterogeneous iso-intense signal on the T1-weighted images and a hypointense signal on the T2-weighted images (Image 1) (Image 2). It extends into the right occipital condyle. CT scan without and with contrast (Image 3) reviled right-sided petro-clival mildly expansile lytic lesions; which showed sclerotic rim and few internal patchy ossified matrix. No aggressive bone distraction was noted.

Management options were discussed with the patient and an immediate family member including the risks of surgery. Decision was made to proceed with the surgical resection of the tumor as the most likely clinical diagnosis based on the radiological images was clival chondrosarcoma.

The patient was booked for an endoscopic transnasal transsphenoidal resection of the clival tumor + intra-operative frozen section. (Image 4) shows an endoscopic image of the tumor intra-operatively. During surgery, two samples were sent for frozen section and another sample was sent as a permanent specimen for histological examination. The first frozen sample came back showing benign low grade spindle cells lesion and tiny fragment of benign bone, and the second sample came back as benign low grade spindle cells lesion. A discussion was made between the Rhinologist, Neurosurgeon and Histopathologist and they all agreed that the tumor features consist with a benign Fibro-osseous lesion. Decision was made then to only debulk the tumor and reconstruct the area.

Surgery was uneventful and she had no post-operative complications noted. The patient was discharged in a stable condition day 2 post-operatively with no headache, nasal bleeding or watery nasal discharge. She was seen 1 week post-operatively with no complaint. A nasal endoscopic examination was done in the clinic and showed a healthy well-healing mucosa with no signs of infection. (Image 5).

Histological examination showed a benign fibro-osseous lesion with features of fibrous dysplasia, spindle cells and few giant cells, which were consistent with a benign lesion. A tissue sample was sent out for molecular studies (MDM2 amplification) to rule out a well differentiated/low grade osteosarcoma. The result showed absence of MDM2 amplification. Final diagnosis was benign clival fibro-osseous tumor. The case was discussed in the tumor board and they all agreed that it’s a benign lesion of the clivus, and planned for 3 months follow up with MRI scans.

Image 1. MRI (T1 with contrast) of the clival tumor

Image 2. MRI (T2) of the clival tumor

Image 3. CT scan of the clival tumor in the sagittal, coronal and axial views

Image 4. Endoscopic image of the tumor intraoperatively.

Image 5. Endoscope image of the healthy well-healing mucosa 1 week postoperatively

Discussion

A patient with a benign fibro-osseous tumor of the clivus appeared with a history of headache in this case. The clivus is a small dip behind the dorsum sellae of the sphenoid bone. It is found in the midline area of the skull base and is made up of the basilar part of the occipital bone and the corpus ossis sphenoidalis. This portion of bone near the base of the skull is surrounded by the brainstem's major structures and nerves, as well as critical arteries such as the internal carotid arteries. Its major function is to divide and connect the numerous anatomical compartments of the skull, as well as to serve as a landmark for the anatomical atlanto-occipital alignment.

Only a few cases of clival fibro-osseous lesions have been reported in the literature. [10] Many cases of fibro-osseous lesions at the base of the skull have been identified and discovered by chance. [9-11] A variety of illnesses affect the clivus, including neoplasms, non-neoplastic, inflammatory, and traumatic lesions. Clival diseases can be asymptomatic or manifest themselves in a variety of ways, ranging from a generalized headache to cranial nerve palsies and life-threatening complications. [9-10] Slow-growing fibro-osseous lesions can often be seen in the absence of symptoms. It primarily affects people in their early adulthood (20-30 years) and is more common in women than in men. [12] In this case, our patient had intermittent headaches that were positioned posteriorly.

The most prevalent site for fibro-osseous lesions of the skull base is the clivus. [13-14] Early lesions are more radiolucent, but later lesions are more opaque, with the characteristic "ground glass" or "peau d'orange" on radiographs. [12] On a CT scan, fibro-osseous tumors look like osteolytic lesions with a central region of mineralization and sclerotic margins. MRI findings are influenced by the degree of lucent and sclerotic regions, as well as the structure and volume of marrow in the cancellous clivus. [12-15] A high T1 signal on MRI indicates fatty transition, whereas T2 appears as a low to high signal intensity. Diagnostic confusion on MRI arises when the conventional finding of low signal intensities on T1- and T2-weighted images is absent yet MRI contrast enhancement is still detectable. A neoplasm is a term used to describe this situation. CT scanning is advised in this scenario, and it has previously been reported that 56 percent of CT scans reveal ground-glass opacity, with other forms such as homogenously dense and cystic opacity also present. [15]

Individuals with fibro-osseous lesions should be monitored closely and have serial imaging done, especially if they are asymptomatic. Fibro-osseous lesions are mainly treated with clinical observation because the majority of patients are asymptomatic. [9] Connective tissue and varied amounts of mineralized substances, which may be bony or cementum-like structures, make up fibro-osseous lesions. Due to the tendency of various fibro-osseous lesions to have similar histopathologic appearances, and the management of each lesion is different, it is vital for oral radiologist to differentiate and confirm the diagnosis.

Surgery is usually reserved for cases of worsening or intolerable deformity, cranial nerve involvement, condyle extension, severe discomfort, or malignant transformation. While many fibro-osseous lesions in the craniofacial region need open or mixed techniques to access the tumor, fibro-osseous lesions in the skull base can often be treated by endoscopic endonasal surgery (EES) with minimal patient morbidity. Solitary clival lesions without condylar extension can be treated conventionally or endoscopically, but in rare cases, a more comprehensive treatment is required. Dissecting devices can drill or fragment fibro-osseous lesions because they are softer than normal bone.

Conclusion

A patient with a benign fibro-osseous tumor of the clivus was shown in this report. Radiographic imaging, such as classical radiological findings on CT and MRI scans, as well as the presence of classic symptomatology and examination results, can usually be used to make the diagnosis of clival tumors. Slow-growing lesions can often be seen in the absence of symptoms. Fibro-osseous lesions of the skull base are usually painless, with symptoms appearing gradually. Evaluation and therapy must take a multidisciplinary approach. Radiology is vital in the diagnosis of fibro-osseous lesions in the skull and skull base. When other more frequent causes of headache and/or cranial nerve symptoms have been ruled out, it is crucial to remember that these patients may develop new symptoms that mask more serious disorders. Because these lesions may recur, serial follow ups are essential.

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