LEGENDS 
Figure 1: CT scan images on axial (A) and coronal (B) planes. Partially cystic, expansive lesion infiltrates and erodes the petrous bone, extending with its more solid component, above the mastoid region, inferiorly along the upper portion of the latero-cervical region (A and B). The lesion extends intracranially, budging within the adjacent portion of middle and posterior fossa. (C) Axial 3D T2 weighted-imaging better highlights the inhomogeneous cystic content and the infiltration of the posterior part of the bony labyrinth. (D) CT scan axial imaging showing the removal of the mastoid part of the lesion, with air within the surgical cavity (arrowhead).
Figure 2. Serial MR axial fat-saturated images T2 images at the mid-level of the bony labyrinth (upper row) and slightly inferiorly (lower row), performed 1 (A, B), 4 (C, D) and 7 (E, F) months after surgery. The images clearly shows the significant volumetric reduction  of the lesion (arrowheads) with ossification of the petrous bone and the inner ear bony structure (dotted line in A and C).