Buns on the inner thighs can be caused by sebaceous cysts, lipomas and boils. 1. Sebaceous cysts: If the sebaceous glands in the skin of the inner thighs are blocked, this can lead to a large accumulation of sebum in the pores and a swelling. 2. Lipoma: If normal fat-like tissue grows between the subcutaneous skin and the muscle at the base of the inner thigh, a lipoma may form and a lump may appear. 3. Boils: Staphylococcus aureus and other pathogenic bacteria invade a single hair follicle and its surrounding tissues on the medial thigh root, which can lead to localized acute suppurative lesions of the hair follicle, and lumps may appear. The cause of the inner thigh root bag more reasons, it is recommended that patients go to the regular hospital in a timely manner, to clarify the cause of the disease, under the guidance of the doctor for standardized treatment.