Right anterolateral foramen magnum mass compresses the cervico-medullary junction and upper cervical cord and mostly displaces the right vertebral artery towards the midline. Exhibits iso signal on T2, high signal on FLAIR and low signal on T1 and enhances homogeneously on post-contrast series with an enhanced dural tail overlying the clivus. It measures 5.8 x 2 x 2.3 cm in maximum CC, TS and AP axises. Dilated ventricular system.