Eksopl does have real health issues which are apparently very serious, he spent time in a hospital and he doesn't want to talk about it publicly, but I'm not sure if it's a tumor.

I think that idea stems from people joking about Eksopl and AoC (Who did have a tumor) in the aftermath of Easymodo's death, and then people took it seriously and so the confusion began. Chinese whispers, you know?

But then again, you might be more informed if you're in touch with IRC, and maybe even Eksi himself.