What are causes of periodontal cysts? I have one which will be removed this coming week. It is benign. My oral surgeon mentioned this is very rare and could have been growing for years. Could it be a cause of lupus or connected to it in some way? Usually, many of my medical tests state there is/has been inflammation but no one could identify where. I also had skin cancer (basal) removed 6 mo. ago. Any ideas to enlighten me would be great. Thank you.