MKI67 and cholesteatoma of middle ear: Currently, hyper-proliferation of keratinocytes has been discovered in middle ear cholesteatoma, demonstrated by significantly high expression of numerous epithelial cell proliferation markers such as proliferating cell nuclear antigen (PCNA), Ki-67, cytokeratin (CK) 13, and CK16 in middle ear cholesteatoma epithelium [13–15].