Table 2. Toyama classification of spinal dumbbell tumors based on MRI shape and three-dimensional location.

Classification by Asazuma et al. [7]

*Subtypes based on the extent of extra-foraminal tumor extension

MRI, magnetic resonance imaging

Type	Tumor location	Subtype (if present)*
Type I	Intradural and extradural	n/a
Type II	Extradural with compression in intervertebral foramen	A – Extradural and foraminal
		B – Extradural and paravertebral
		C – Foraminal and paravertebral
Type III	Intradural and extradural with compression in intervertebral foramen	A – Intradural, extradural, foraminal
		B – Intradural, extradural, and paravertebral
Type IV	Extradural and intravertebral (invasion of vertebral body)	n/a
Type V	Extradural and extralaminal (invasion of lamina)	n/a
Type VI	Extradural with multidirectional invasion of bone	n/a