development was assessed by preoperative computed tomography and classified into one of the four degrees following the 2015 JOS staging system: MC0 (almost no cell growth), MC1 (cellular structures only around the mastoid antrum), MC2 (well-developed cellular structures), and MC3 (cellular structures extending to the peri-labyrinthine area) (Figure 2) .
The technique chosen is generally based on the extent of the disease and the surgeon's preference, and it ranges from canalplasty with skin grafting for lesions confined to E AC, to canalplasty or canal-wall-up mastoidectomy with reconstruction of canal defects for lesions involving mastoid cells
, to canal-wall-down mastoidectomy for lesions with large wall defects exhibiting mastoid erosion.
The computed tomography scan indicated normal middle and inner ear structures with well pneumatized mastoid cells
in both ears preoperatively (Figure 1a).
A CT scan, performed two days later, showed right side mastoid cells
filled with liquid and thickening of mucosa.