Benign notochordal cell tumor

Benign notochordal cell tumours (BNCT) are vertebral lesions that are usually asymptomatic and discovered incidentally on imaging of the head or spine. As this is a poorly-recognised entity, it can often be confused with aggressive vertebral lesions, such as a chordoma, when it is seen on imaging.

Epidemiology

Autopsy studies show BNCTs are extremely common with a reported incidence of up to 20% in cadaveric specimens ¹. While only the larger of these lesions can be seen on imaging it is felt they are under-reported ². 

Clinical presentation

The vast majority of lesions are asymptomatic but a small proportion of patients can present with chronic back pain and coccydynia ².

Pathology

Location

The distribution is similar to chordomas:

• clivus (50%)
• vertebrae
• sacrum/coccyx

Radiographic features

CT

• vertebral body sclerosis
  • can extend to the cortex or involve the entire vertebra
• preserved trabeculae
• no cortical destruction

MRI

• well-defined osseous lesions
  • T1: hypo- or isointense. May; 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

Nuclear medicine

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 BNCTs to transform into chordomas is not known and many advocate interval follow-ups ⁵.

Differential diagnosis

• chordoma
• ecchordosis physaliphora
• notochordal vestiges of the intervertebral diskdisc