benign notochordal cell tumor
Benign notochordal cell tumors are vertebral lesions that are usually asymptomatic and discovered incidentally on imaging of the head or spine. As this is a poorly-recognized entity, it can often be confused with aggressive vertebral lesions, such as a chordoma, when it is seen on imaging.
Initially, the term intraosseous chordoma was used although given that the relationship between these lesions and chordomas remains uncertain it is probably best to avoid this term. Another term that has been used previously is giant vertebral notochordal rest.
Autopsy studies show benign notochordal cell tumors are extremely common with a reported incidence of up to 20% in cadaveric specimens . While only the larger of these lesions can be seen on imaging it is felt they are under-reported .
The vast majority of lesions are asymptomatic but a small proportion of patients can present with chronic back pain and coccydynia .
The distribution is similar to chordomas:
- clivus (50%)
- vertebral body sclerosis
- can extend to the cortex or involve the entire vertebra
- preserved trabeculae
- no cortical destruction
- well-defined osseous lesions
- T1: hypo- or isointense; may demonstrate hyperintense intra-lesional punctiform foci representing fat lobules due to entrapped bone marrow
- T2: hyperintense
- T1 C+ (Gd): usually no enhancement (in around 75% of cases)
- DWI: no restricted diffusion
- no soft tissue component
Often show no uptake on bone scintigraphy.
Treatment and prognosis
While there is a consensus that no specific treatment is required for asymptomatic lesions, the long-term malignant potential of benign notochordal cell tumors to transform into chordomas is not known and many advocate interval follow-ups . In most instances they are quiescent but reports of these tumors co-existing with chordomas or perhaps degenerating/transforming into chordomas exist .