Hi ! Good evening. I am Dr Shareef answering your query. It might be a hematoma due to some unnoticed trivial trauma during sleep, or a benign dermoid cyst. It might not be possible to give a definite opinion on it without a physical examination of the lesion. I would suggest you to show it to a general surgeon in your area to have a definite diagnosis and management. I hope this information would help you in discussing with your family physician/treating doctor in further management of your problem. Please do not hesitate to ask in case of any further doubts. Thanks for choosing health care magic to clear doubts on your health problems. Wishing you an early recovery. Dr Shareef