I have an arachnoid cyst that I had fenestration surgery done on May 2011. I had an mri done this morning due to increase head pain (feels like a knife is stabbed in the top of my head) and neck and spinal cord pain. I have also fallen three times in the eek. The cyst has grown from 3.6cmx2.4cm to 4.0cmx2.8cm in a month and a half. This is understand from my past and I understandno this. But the mri also for the first time showed a 1.0cmx.80cm nodule like mass inside the cyst. report stated maybe due to increased protein . Any help on what this may mean?