Intramedullary tumors
These neoplasms are located directly within the spinal cord tissue. More than 90% of them are glial tumors, among which are:
- Astrocytoma (astrocytoma). Most commonly detected in children and young adults. It is characterized by a diffusely infiltrative growth pattern, making it inoperable.
- Ependymoma (ependymoma). Typical for adult patients and individuals with neurofibromatosis type 2 (NF-2). Unlike astrocytoma, it has clear margins. Key radiological patterns include the "cap sign" (cap sign, indicating hemorrhage), satellite cyst formation, and accompanying syringomyelia (syrinx).
Other, less frequent intramedullary lesions include:
- Haemangioblastoma (haemangioblastoma), which is closely associated with von Hippel-Lindau syndrome (VHL syndrome).
- Ganglioglioma (ganglioglioma), characteristically occurring predominantly in childhood.
- Metastases (rarely encountered).
It is important to remember tumor mimics (tumour mimics). Within the spinal cord, neoplastic processes can be simulated by demyelinating diseases such as multiple sclerosis (MS — multiple sclerosis) and neuromyelitis optica (NMO — neuromyelitis optica).
Intradural extramedullary tumors
This group is localized beneath the dura mater but outside the spinal cord itself. The main representatives are:
- Nerve sheath tumours (nerve sheath tumours). These include schwannoma (schwannoma) and neurofibroma (neurofibroma). They can be either solitary or multiple. Multiple schwannomas are a typical manifestation of NF-2, while multiple neurofibromas are characteristic of neurofibromatosis type 1 (NF-1).
- Meningioma (meningioma). Classically, this is a tumor of elderly individuals. An exception is patients with NF-2: in them, meningiomas develop at a young age and are often multiple.
- Metastases. In this space, they can spread leptomeningeally (most commonly in breast or lung cancer), or present as "drop metastases" (drop metastases) descending along the cerebrospinal fluid pathways (characteristic of medulloblastoma, ependymoma, and others).
Mimics (tumour mimics) in this space can include intervertebral disc herniation, facet joint cysts, as well as systemic processes such as sarcoidosis and granulomatosis with polyangiitis.
Extradural and primary vertebral tumors
These lesions affect structures located external to the dura mater, including the bony apparatus of the spine.
The most common extradural tumor is metastases, which structurally are divided into osteolytic and osteoblastic.
Primary vertebral tumors are classified based on their degree of aggressiveness:
- Benign (benign): haemangioma (haemangioma), osteoid osteoma (osteoid osteoma), aneurysmal bone cyst (aneurysmal bone cyst), and eosinophilic granuloma (eosinophilic granuloma). They have a typical, easily recognizable radiological appearance.
- Locally aggressive (locally aggressive): chordoma (chordoma) and giant cell tumour (giant cell tumour).
- Malignant (malignant): multiple myeloma / plasmacytoma (multiple myeloma / plasmacytoma), chondrosarcoma (chondrosarcoma), Ewing sarcoma (Ewing sarcoma), and osteosarcoma (osteosarcoma).
Role of imaging modalities
Modern diagnostic imaging is the foundation of spinal oncology, allowing a detailed assessment of the nature of the pathology according to the WHO classification (WHO grading) using indirect methods.
- MRI and CT provide the most accurate assessment of tumor invasion into surrounding soft tissues. Visualization of the extent of intraspinal spread and evaluation of central spinal canal compression are particularly important.
- PET/CT (PET/CT) serves as the modern standard (standard of care) for the staging of all patients with bone and soft tissue sarcomas. The method is also indispensable for monitoring treatment response and regular follow-up for early detection of recurrences.
Briefly: answers to topical questions
What radiological signs are characteristic of a vertebral hemangioma?
For an asymptomatic vertebral hemangioma, axial CT scans show the «polka-dot pattern», while sagittal reconstructions show the «corduroy sign». On sagittal T1-weighted and T2-weighted MRI scans, the body of the affected vertebra exhibits a high-intensity signal due to the fatty component, against which linear striations with a low signal from thickened bone trabeculae are visible. The aggressive variant of hemangioma demonstrates a hypointense signal on T1-weighted images and expansile growth.
Which diseases can mimic intramedullary tumors, and what are their MRI features?
Intramedullary tumors can mimic demyelinating diseases such as multiple sclerosis and neuromyelitis optica. Multiple sclerosis plaques in the spinal cord are visualized on T2-weighted images as wedge-shaped or oval hyperintense lesions. They are located predominantly dorsally and laterally, and are characterized by variable contrast enhancement. In transverse myelitis, the lesions occupy most of the spinal cord cross-section and can extend longitudinally over several segments.
For quick memorization of the three localization levels, imagine the principle of a matryoshka doll: the core is the spinal cord (intramedullary tumors), the inner sleeve is the meninges (intradural extramedullary), and the rigid outer framework is the bones and outer tissues (epidural).
Class and exam questions
What is the main difference between astrocytoma and ependymoma on imaging?
Astrocytoma grows in a diffuse-infiltrative manner, rendering it inoperable. Ependymoma, in contrast, has clear margins and is often accompanied by the «cap sign» (cap sign), satellite cysts, and syringomyelia.
What diseases mimic spinal cord tumors?
In the intramedullary space, these are demyelinating processes: multiple sclerosis (MS) and neuromyelitis optica (NMO). In the extramedullary space, these include disc herniations, facet joint cysts, sarcoidosis, and Wegener's granulomatosis.
How does neurofibromatosis affect nerve sheath tumors?
In neurofibromatosis type 2 (NF-2), patients frequently develop multiple schwannomas. Neurofibromatosis type 1 (NF-1) is characterized by the presence of multiple neurofibromas.
What are drop metastases?
These are drop metastases (drop metastases), which spread from a primary tumor (e.g., medulloblastoma or ependymoma) downward along the cerebrospinal fluid pathways, settling in the intradural extramedullary space.
What else to study on this topic
- Radiological semiotics of the cap sign and syringomyelia in ependymomas.
- Features of leptomeningeal dissemination of breast and lung cancer metastases.
- Typical radiological picture of benign vertebral tumors (hemangioma, osteoid osteoma).
- Specifics of using PET/CT to monitor treatment response in sarcomas.
- Differential diagnosis of multiple sclerosis (MS) and neuromyelitis optica (NMO) from true tumors.
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