Large nodular bumps at the base of the thighs may be caused by boils, enlarged lymph nodes, sebaceous cysts or lipomas. 1. Boils: acute suppurative inflammation in the deep part of the hair follicles and the surrounding tissues, hard bumps appear on the local skin of the thighs which are initially follicular inflammatory papules, and after the inflammation spreads, hard nodules are formed, which can be accompanied by redness, swelling and pain. 2. Swollen lymph nodes: there are many lymph nodes in the groin at the thigh root, and when there is inflammation near the thigh root, it is easy to have swollen lymph nodes. This kind of inflammation is usually caused by viral, bacterial and other infections, and the patient may even be accompanied by pain and other symptoms in addition to large nodule bumps at the thigh root. 3. Sebaceous cyst: it is a kind of cyst formed by the restriction of sebum discharge, which is manifested by the appearance of bean to coin-sized lumps at the root of thighs, with smooth edges, which can be moved under the skin after being pushed and squeezed. 4. Lipoma: Lipoma is a benign tumor formed by proliferation of mature fat tissue. It can occur in any part of the human body. When the patient’s body is too obese, there will be the performance of large nodular bumps at the root of thigh. There are many reasons that cause large nodular bumps at the root of the thigh, patients should go to the hospital in time to do the relevant examination, identify the cause of the disease under the guidance of the doctor for treatment.