Epidemiology and preferred localization
Chordomas are classified as low- to intermediate-grade malignant tumors. Despite their relative rarity in general oncology (2–4% of primary malignant bone lesions), chordoma ranks second in frequency among primary malignant tumors of the spinal column. Furthermore, this neoplasm accounts for over 50% of all primary sacral tumors.
The disease predominantly manifests in the older age group—from 50 to 70 years. It has been noted that in elderly patients, men are significantly more frequently affected, especially when the tumor is located in the sacral region.
The main feature of chordoma is its strictly midline location. The tumor affects the axial skeleton and has two preferred localizations:
- Sacrococcygeal region (50% of cases): typically, the pathological process is localized below the level of the S3 vertebra.
- Skull base (clivus) region (40% of cases): the second most frequent zone of involvement.
- In other parts of the spine, the neoplasm is rare, with the cervical spine being affected more frequently than the thoracic or lumbar spine.
Clinical presentation and diagnostic imaging
Chordomas are characterized by a slow growth rate. Consequently, clinical symptoms, which are usually associated with the compression of adjacent anatomical structures, may persist for a long time before the definitive diagnosis is made.
Diagnostic imaging plays a key role in identifying and staging the process:
- Radiography: In early stages, the tumor is easily missed. A standard radiograph is informative only when the neoplasm is large in the pelvis or lumbosacral region. The main radiological sign is bone destruction, sometimes accompanied by amorphous calcification.
- CT and MRI: These methods reliably visualize the soft-tissue component of the tumor. Massive tissue extension anteriorly into the pelvic cavity is frequently determined.
MRI semiotics of chordoma:
- T1-weighted images (T1WI): signal varies from intermediate to low.
- T2-weighted images (T2WI): a high signal is characteristic, although this sign is nonspecific. The formation of a lobulated hyperintense structure is typical for chordoma but may mimic chondrosarcoma.
- Contrast enhancement: following gadolinium administration, characteristic contrast enhancement along the tumor septa is observed.
Treatment, prognosis, and benign counterparts
The primary and most effective treatment method for chordoma is wide surgical excision (wide excision). In situations where the tumor is deemed unresectable or wide resection is technically impossible due to the involvement of critical structures, radiation therapy is used.
Prognosis and complications:
- Distant metastases are rare.
- Death usually results from severe complications caused by the relentless local spread of tumor masses.
- Local recurrence (often multifactorial) poses a huge problem. It is recorded in 40% of cases. It is hypothesized that one of the main causes of recurrence is iatrogenic implantation of tumor cells into tissues during surgery.
Benign notochordal lesions: There are benign counterparts to malignant chordoma—benign notochordal rests (benign notochordal rest) or benign notochordal cell tumors. They occur strictly in the same sites of the axial skeleton, but do not progress clinically.
The main radiological difference between benign counterparts and chordoma is the complete absence of signs of cortical bone destruction and the absence of an extraosseous soft-tissue component. In modern literature, whether these benign rests can serve as precursors to classical malignant chordoma remains a subject of scientific debate.
Briefly: answers to topical questions
Which cranial nerves and anatomical structures are most frequently compressed in chordoma of the clivus?
In chordoma of the clivus (clivus), adjacent structures are most frequently compressed, which clinically manifests as lower cranial nerve palsies. The exact list of involved anatomical formations is not detailed, but the tumor is localized in the area of the spheno-occipital synchondrosis (spheno-occipital synchondrosis of the clivus), basiocciput, and the apex of the petrous part of the temporal bone.
What histological variants (subtypes) of malignant chordoma are distinguished?
The following histological variants of malignant chordoma are distinguished:
- Chordoma, NOS — includes chondroid chordoma and poorly differentiated chordoma.
- Dedifferentiated chordoma — an independent entity.
What specific radiation therapy methods are used to treat unresectable chordomas?
Proton therapy is specifically used to treat unresectable chordomas. This method is the preferred type of radiation treatment when critical structures are in close proximity and standard radiation doses cannot be delivered. Proton therapy is also highly effective in repeat courses of irradiation for chordoma recurrences. In general, radiation therapy is indicated in unresectable cases or when wide excision (wide excision) is technically unfeasible.
To remember the two main localizations of chordoma, use the association "From head to tail in a straight line": clivus (base of the skull) and sacrum (the very bottom of the spine), everything strictly along the midline.
Class and exam questions
How to differentiate chordoma from chondrosarcoma or metastases on MRI?
The key differential diagnostic sign is the strictly midline origin of chordoma. Both tumors can produce a lobulated hyperintense structure on T2WI, but chondrosarcomas and metastases are more often displaced from the midline.
What is the typical localization of chordoma in the sacrum?
In lesions of the sacrococcygeal region, the tumor focus is usually located in the lower sections, below the level of the S3 sacral vertebra.
Why do chordomas recur so frequently?
Recurrences occur in approximately 40% of cases. This is believed to be due to the implantation (seeding) of tumor cells into surrounding tissues directly during surgical intervention.
What else to study on this topic
- Differential diagnostic imaging of midline spinal tumors
- Ewing sarcoma and Askin tumor: CT and MRI presentation of bone lesions
- Malignant vascular bone tumors (hemangioendothelioma and angiosarcoma)
- Principles of wide excision in orthopedic oncology
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