How fast does a thymoma tumor grow?

Question

if the tumor is the size of a small egg, how long has it approximately been growing?

Answer 1

Of all tumors, thymoma is probably one of those that's hardest to predict. Thymomas can range from those that behave relatively indolently to those that behave very aggressively and be very invasive. The best guess for a tumor that is clinically evident (meaning causing symptoms and therefore diagnosed) is probably in the order of months. But it could potentially have been there but growing slowly for years.