Hi @irene5, I'm sure you've search the Internet thoroughly. None-the-less, I thought I'd post this article about cholesteatoma from Healthline:
Cholesteatoma: Causes, Symptoms, and Diagnosis https://www.healthline.com/health/cholesteatoma

According to the article, cholesteatomas can return and it is important to catch a regrowing cyst early. I'm also @genuinekim and @judysmayo to get their experiences about recurrence and symptoms they experienced.

Irene, does your son or is your able to tell you when he is not well or is experiencing early symptoms like the ear draining a foul smellng fluid or pressure in the ear?