The causes of a tendinous bag in the groin of the thigh are inguinal lymphadenitis and inguinal hernia. 1. Inguinal lymphadenitis: it is mainly manifested by enlarged lymph nodes in the groin area and localized redness, swelling, heat and pain. Some patients may be accompanied by symptoms such as chills and high fever. It is mainly caused by infection of tissues or organs in other parts of the body, low immunity, etc. It should be actively treated with anti-infection. 2. Inguinal hernia: manifested as a pear-shaped, retractable, soft mass in the inguinal area when standing or walking, the patient will also have local pain, swelling, abdominal pain, abdominal distension, defecation, defecation difficulties, mainly due to abdominal surgery, chronic liver disease, cirrhosis and ascites and other diseases, requiring surgical treatment. When there is a tendon bag in the groin of the thigh, it is necessary to go to the hospital at the first time, early diagnosis, early treatment.