Final answer:
Cholesteatoma is caused by bacterial infection which can lead to chronic inflammation, resulting in the abnormal growth of a skin cyst in the middle ear.
Step-by-step explanation:
The cause of Cholesteatoma formation due to marginal perforation followed by endothelial erosion can be attributed to a bacterial infection. Cholesteatoma is a type of ear condition that occurs when a skin cyst grows abnormally in the middle ear behind the eardrum, often due to chronic inflammation. According to the discussion, the chronic inflammation that results in a torn membrane and the erosion of inner ear bones can be due to increased pressure from fluid buildup in the middle ear. This fluid buildup can be induced by a bacterial infection which leads to the condition known as otitis media with effusion, with or without active infection. As a result, bacterial infection is the most likely cause of Cholesteatoma in this scenario.