Clival Chordoma and Calvarial Tumors
Tumors arising from the clivus—the midline portion of the skull base located anterior to the brainstem—are exceedingly rare, yet they demand a high level of subspecialty expertise because of their intimate relationship to critical neurovascular anatomy (the brainstem, cranial nerves, the basilar artery, and venous plexuses). The most common primary tumors in this region are chordoma and chondrosarcoma.
Tumors involving the bones of the cranial vault (calvarium) are more common and may be benign or malignant, primary or metastatic. A sound diagnostic and treatment strategy is built on the integration of the clinical presentation, imaging (CT/MRI), and histopathologic confirmation when clinically necessary.
Clivus vs calvarium: what do these terms mean?
Two distinct bony regions of the skull—requiring fundamentally different surgical strategy and oncologic planning.
The clivus is a midline portion of the skull base located anterior to the brainstem. In this region, cranial nerves (vision, eye movements, swallowing), major vessels, and other critical neurovascular structures are in close proximity. Even slow-growing tumors may produce significant neurological symptoms given the confined anatomy.
The calvarium comprises the bones forming the roof and lateral aspects of the skull. Lesions in this region often present as a palpable skull mass or are discovered incidentally on CT/MRI of the brain. The principal diagnostic challenge is to distinguish benign, indolent lesions from malignancy, including metastatic disease.
Symptoms and neurological signs
Clival tumors typically present with neurological symptoms. Calvarial lesions more often cause local findings (a palpable mass or pain) or are detected incidentally on imaging.
Clivus (skull base)
- Diplopia (often from abducens nerve involvement) and ocular motility disturbance.
- Headache or a sense of pressure, sometimes progressive.
- Cranial neuropathies: facial numbness or pain, hoarseness, dysphagia, sensory changes.
- Long-tract signs: weakness, imbalance, gait disturbance when the brainstem is compressed.
Calvarium (skull vault)
- Painless, slowly enlarging mass, often seen in benign lesions.
- Painful or rapidly enlarging mass, raising concern for a more aggressive process.
- Less commonly, symptoms due to intracranial extension or compression of adjacent neurovascular structures.
Imaging: what CT and MRI tell us
Imaging is the primary roadmap that shapes treatment strategy. For clival tumors, the critical factor is the lesion’s relationship to adjacent cranial nerves and vascular structures. For calvarial lesions, interpretation focuses more on patterns of bony change and lesion margins.
CT is particularly valuable for assessing bone destruction, calcifications, sclerotic margins, and involvement of the inner and outer tables within the diploë of the calvarium. MRI is critical for evaluating soft-tissue extension and the lesion’s relationship to the brainstem and adjacent neurovascular anatomy.
Indolent / benign patterns: well-defined, sclerotic borders; diploic expansion with disproportionate involvement of one table.
Aggressive / malignant patterns: ill-defined margins; multifocal disease; symmetric destruction of both inner and outer tables; associated soft-tissue mass.
For clival lesions, additional studies—such as specialized vascular imaging or tailored protocols—may be necessary depending on extent and vessel involvement. The diagnostic and treatment plan is always individualized.
Our Neuroknife approach: when to observe, biopsy, or treat
At Neuroknife, our priorities are diagnostic clarity and timely, safe treatment—always with preservation of neurological function as the central principle.
Our decision-making is structured around three core questions:
(1) Are there clinically meaningful symptoms?
(2) Does imaging suggest indolent biology or aggressive behavior?
(3) Would management change based on histopathology?
Neurological symptoms (e.g., diplopia, cranial neuropathies) or clear interval growth on imaging → proceed to diagnostic and/or therapeutic intervention.
Non-diagnostic imaging or concern for malignancy/metastatic disease → consider biopsy to guide definitive planning.
In clival tumors, the operative goal is not “maximal resection at any cost.” Our aim is maximal safe resection in a high-risk anatomical corridor, often integrated with high-dose radiotherapy (e.g., proton therapy) to achieve reliable long-term local control.
We draw clear boundaries between general, statistically expected parameters and what requires personalization—including anatomy, age, histology, baseline neurological status, and the patient’s goals.
Clival chordoma: what it is and how it is treated
A typically slow-growing tumor arising from notochord remnants, most often in the midline. The principal challenge is regional anatomy—not growth rate.
Chordoma is a neoplasm derived from remnants of the embryologic notochord. Although often slow-growing, it can cause symptoms due to cranial nerve involvement and brainstem compression. Common presentations include diplopia and headache.
Radiographically, chordoma is typically midline and produces characteristic clival bone destruction. On MRI, it often demonstrates high T2 signal and contrast enhancement.
• Small lesion, asymptomatic patient with concordant imaging → close surveillance may be appropriate.
• Symptoms or documented growth → prioritize surgical treatment with the goal of maximal safe resection.
• Because chordomas frequently require high-dose radiotherapy, we plan from the outset using a comprehensive strategy (surgery designed with adjuvant radiotherapy in mind).
Recurrence is relatively common and requires reassessment for potential re-operation and/or radiotherapy. Our goal is durable local control while preserving neurological function and maximizing quality of life.
Skull base chondrosarcoma: key distinguishing features
It can resemble chordoma on imaging, but it more often arises off-midline and has a distinct biological profile.
Chondrosarcoma is a tumor arising from cartilaginous tissue and mesenchymal cells. At the skull base, it often involves the clival region or the petroclival junction and may present with diplopia, headache, and multiple cranial neuropathies due to compression of adjacent neurovascular structures.
Treatment typically includes maximal safe surgical resection and high-dose radiotherapy, aiming for optimal local control, particularly when complete resection is not anatomically feasible.
Surgical approaches to the clivus (endoscopic and open techniques)
Approach selection is driven by the vertical level of clival involvement (upper, middle, or lower third), lateral extension, and whether there is intradural involvement.
Surgical options broadly include endoscopic endonasal and open microsurgical approaches. Endoscopic techniques have expanded significantly and, in selected cases, offer direct access to midline lesions while avoiding extensive craniotomy.
Open approaches are chosen based on the clival segment involved and extent of disease:
- Upper third: frontotemporal/orbitozygomatic or subtemporal approaches.
- Middle third: transpetrosal or retrosigmoid approaches, depending on lateral extension.
- Lower third: approaches involving the occipital condyle or far-lateral corridors when indicated.
Calvarial tumors: benign vs malignant (a practical guide)
In calvarial disease, clinical history, growth rate, and imaging patterns often provide reliable insight into biological behavior.
Benign lesions include congenital cysts (epidermoid and dermoid), fibrous dysplasia, eosinophilic granuloma (benign histiocytosis), osteoma, and hemangioma. Malignant lesions include sarcoma, lymphoma, and—most commonly—metastatic disease.
• a slowly enlarging, painless mass with well-circumscribed margins on imaging → pattern more consistent with benign disease.
• a painful, rapidly enlarging mass with ill-defined margins and/or multifocal lesions → warrants urgent, structured evaluation with biopsy or complete surgical excision.
In patients with a known cancer history, any new lesion involving the calvarium is assessed with a high index of suspicion for metastatic disease. Management is individualized based on tumor histology, systemic staging, and the broader oncologic plan.
Common benign calvarial lesions
Most benign calvarial lesions can be definitively treated with appropriate surgical excision. Alternatively, truly asymptomatic lesions without documented growth may be monitored safely with structured surveillance.
Epidermoid / dermoid cyst
These are benign congenital lesions resulting from ectodermal inclusion. They typically appear as well-demarcated osteolytic lesions of the calvarium. On MRI, epidermoid cysts often demonstrate diffusion restriction (DWI restriction), which is highly useful diagnostically. When indicated, treatment is complete excision of the lesion including its capsule to achieve durable local control.
Fibrous dysplasia
A benign bone disorder in which normal bone is replaced by fibro-osseous tissue. It commonly involves the sphenoid and frontal bones and may lead to deformity and/or neurovascular compression. Radiotherapy is contraindicated due to a documented risk of malignant transformation. Surgery is considered only when there is a clear clinical indication—such as significant deformity, persistent pain, or cranial nerve dysfunction from compression.
Osteoma
A benign, slow-growing bony tumor composed of mature cortical bone. It is often a local or cosmetic concern; surgical removal is discussed when symptomatic or when it causes substantial functional or aesthetic impact.
Malignant calvarial disease: sarcoma and metastases
Here, our goals are diagnostic precision, durable local control, targeted decompression when needed, and a clearly documented integration of the lesion into the patient’s overall oncologic plan.
Sarcoma
Calvarial sarcomas are rare but biologically aggressive. Imaging often shows irregular, poorly defined margins with an osteolytic pattern. Management is based on wide surgical excision with clear margins, including resection of involved dura when present, followed by multidisciplinary oncologic therapy with radiotherapy and/or chemotherapy protocols.
Metastases
Metastatic disease is the most common malignant process involving the calvarium in adults. Lesions may be solitary or multifocal. Imaging patterns vary by primary tumor—some are predominantly osteoblastic (e.g., prostate or breast), whereas others are osteolytic (e.g., lung cancer, melanoma). Surgery is primarily aimed at decompression, symptom control, and histopathologic confirmation, while systemic therapy is planned in collaboration with the oncology team.
Recovery, rehabilitation, and follow-up
Follow-up is tailored to histology, extent of resection, and the multimodality plan (radiotherapy and/or systemic oncologic therapy).
After treatment for clival chordoma or calvarial tumors, we typically organize:
- Protocol-driven imaging surveillance (MRI/CT) aligned with the oncologic diagnosis.
- Neurological assessment, with particular attention to cranial nerve function, ocular motility, and swallowing/phonation.
- An individualized rehabilitation plan with realistic, function-oriented goals for return to daily activities.
- Close coordination with radiation oncology and neuro-oncology to plan adjuvant treatment and optimize long-term local control.
Frequently asked questions (FAQ)
What is the most common cause of diplopia in clival tumors?
Diplopia is often related to involvement or compression of the abducens nerve, as well as other cranial nerves at the skull base. It is a characteristic symptom and warrants specialized neurosurgical evaluation together with targeted imaging.
Chordoma and chondrosarcoma: are they the same?
No. Although both can arise at the skull base and may share imaging features, they have distinct origins and biological behavior. Definitive diagnosis requires histopathologic confirmation and is essential for appropriate treatment planning.
When is observation appropriate instead of immediate intervention?
For small, stable lesions without clinical symptoms and with low-risk imaging features, a structured surveillance plan with MRI and/or CT may be appropriate. The development of symptoms (such as diplopia) or documented growth typically prompts re-evaluation and adjustment of the treatment strategy.
When is biopsy or excision needed for calvarial tumors?
When a lesion shows rapid growth, pain, ill-defined or aggressive imaging features, or when there is a known history of malignancy, biopsy is often required for tissue diagnosis. In selected cases, surgical excision can serve both diagnostic and therapeutic purposes.
Is radiotherapy always required after surgery for clival tumors?
Not always. The need for radiotherapy depends on histology, extent of resection, and residual disease. In chordomas and chondrosarcomas, high-dose radiotherapy is frequently incorporated to optimize durable local control—especially when complete resection cannot be achieved safely.
Specialized neurosurgical evaluation for chordoma and calvarial tumors
If you have been diagnosed with a cranial lesion consistent with chordoma, chondrosarcoma, or a calvarial process, timely evaluation by a specialized neurosurgical team is critical. At Neuroknife, the first step is a clear, evidence-based distinction between lesions that can be monitored safely and those that require timely surgery or tissue diagnosis.
Managing complex skull base neoplasms requires a high-volume, specialized center with years of focused experience and meaningful exposure to comparable cases—such as the Neuroknife team. Deep familiarity with anatomical variability and complication prevention directly influences operative strategy, outcome, and long-term prognosis.
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