A dumbbell-shaped mass on the left at C1/C2 has a component anterior to the cord, which it displaces posteriorly with a subtle increase in T2 signal, and a component within the foramen.
The mass has intrinsically high T1 signal, low T2 signal and probably enhances somewhat although this is difficult to confirm given the prominent intrinsic high T1 signal.
Conclusion:
Morphology of the mass suggests a diagnosis of schwannoma, although occasionally meningiomas can also be dumbbell-shaped. The presence of intrinsic high T1 signal suggests melanin. Both meningiomas and schwannomas have melanotic variants and meningeal melanocytoma is an additional differential diagnosis to consider. A melanoma metastasis is less likely given the extra-axial location.
Overall a malignant melanotic nerve sheath tumour is favoured given the morphology.