A hard mass at the root of the thigh is considered to be caused by enlarged lymph nodes in the inguinal region, and the patient may also have painful manifestations. The most common cause is infection of the soft tissues of the lower extremities and reactive hyperplasia of the local lymph nodes, which can be seen as localized cellulitis after trauma or lymphangitis of the lower extremities secondary to tinea pedis. Patients may also show fever and swelling of the lower extremities, which should be treated actively with symptomatic treatment such as anti-infection and improvement of microcirculation, as well as elevation of the lower extremities to promote venous blood flow back to the inguinal region. In addition, some patients are also caused by tumors, which can be seen in pelvic floor diseases or malignant tumors of the perianal area.