Hi. Since it's from nine months and not increasing, it may be a cyst or a Lipoma. However, I hope u realise it's not possible to diagnose this without seeing and without examining it. Please see a dermatologist/ dermatosurgeon in your city and then he could probably help you with the diagnosis and if it needs to be removed. Let me know if you need any further assistance in this regard. Warm regards. govindmittalatgmail.com