Hi, Thanks for writing in. From the description of the cyst on the head, it appears that it might be a scalp swelling, There are many kinds of swelling involving the head and scalp. Some of these remain inactive for a long time and might become enlarged slowly with time. These are commonly cysts like sebaceous cysts and can have a central opening when looked at closely. There are other cysts like epidermoid cyst or dermoid cyst. Dermoids and epidermoids are slow-growing benign cysts that typically occur in the scalp and the skull of infants and young children. All these cysts are essentially benign. It will help to consult your doctors once you are back from your vacation. Please do not worry.