Lymphatic cyst is a collection of lymphatic fluid with an epithelial lining which can either represent lymphatic malformations or may occur after trauma or operation. Idiopathic lymphatic cyst of the thigh in adulthood is extremely rare. We report a case of a 27-year-old Thai female presented with a rapidly growing mass over her right thigh. https://www.spidertattooz.com/USC-Trojans-9FIFTY-Snapback-Hat/