<s>[INST] Many years ago I was d iagnosed with Tarlov cysts, which are thought to be congenital .M ine are VERY large and may be symptoms of lower back pains.... or not. There is erosion if L3 (1/4 of L3) ,with about 1/3 of my sacrum. Some nerve fibers go through the cysts. I have U. Colitis in remission, and I have been hospitalized many times for rest ^& blood transfusions. The steroids have caused cataracts, glaucoma & severe osteoporosis. When is surgery necessary? ? [/INST] Hello! Thank you for your question on Chat Doctor! I understand your concern. Your clinical situation is very complicated, because colitis can cause irradiating back pain. Taylor cysts are usually asymptomatic and do not need treatment. But in a case like yours, if the erosion of L3 is near the cyst and not because of osteoporosis, I would recommend consulting with a neurosurgeon for the possibility or treatment. A careful physical examination for the neurological signs would be very helpful to determine if there is any articular pain related to the cyst. In this case surgery would be needed. Hope to have been helpful! Best Wishes!  </s>