In Nepal: In this patient, the meninges, brain vein and facial nerve were already exposed (giant cholesteatoma).
A cholesteatoma is described as chronic purulent inflammation of the middle ear with bone destruction, in most cases deriving from squamous epithelium growing from the external auditory canal into the middle ear.
The squamous epithelium of the external auditory canal of a healthy ear and the mucous membrane of the middle ear are completely separated by the tympanic membrane. If this barrier is removed, squamous cells can grow into the tympanic cavity. This pomotes an epidermoid proliferation of squamous epithelium into the middle ear region. The defective drainage of secretions and bacterial super-infection - frequently with Pseudomonas aeruginosa- maintains a chronic inflammatory process of the ingrowing epithelium. This inflammation can spread to the bony parts of the middle and inner ear and successively destroy them.
Source: Praxis Dr. Eberle