Hey do glioma arise on/in calvarium and do they take years to grow big, i mean do they take 7 years to get large without symptom. i have extra axial lesion from seven years without symptoms. do you think it could be cancerous? thank you.:?

Your question is not clearly stated. Glioma is one type of tumor of the brain, not bone. What do you mean by extra-axial lesions? It is not feasible to provide a meaningful opinion without additional information and physical examination and may be some tests.

A glioma is a primary brain cancer and can be slow growing or quite malignant and rapid if high grade. These are not external to the brain. Your description suggests far more likely that you possess an incidental meningioma. Would see a neurosurgeon and get a direct opinion.