A lump at the edge of a woman’s underwear at the base of her thigh may be a lump in the groin or perineum. Possible causes are inguinal hernia, lymphadenitis, lymphoma, vestibular gland cysts, and other diseases, usually accompanied by symptoms of local pain. It may also be a superficially generated lipoma or fibroma of the skin with no obvious pressure pain. Common etiologies are classified as follows: 1. Inguinal hernia: Inguinal hernia is commonly seen as inguinal hernia and inguinal hernia with a lump in the groin in the early stages. Common causes are weakness of the abdominal wall due to congenital or acquired defects, and increased intra-abdominal pressure due to excessive exertion such as coughing and sneezing. Inguinal hernia can be caused by forceful defecation, heavy labor, pregnancy, etc. It is usually treated surgically, with the aid of antibacterial medication in case of infection. If not treated in time, it may lead to more serious abdominal wall damage and even life-threatening incidence such as impaction; 2. Lymphadenitis: it is a benign lesion of lymph nodes caused by infection of lymph nodes by pathogenic bacteria, commonly found in the groin or neck and other parts of the body, which may manifest as enlargement and pain in the groin. It is usually treated with antibiotics and antiviral drugs and in severe cases leads to abscesses that require surgical incision and drainage. If not effectively treated, it may develop into sepsis with the course of the disease; 3. Lymphoma: also called malignant lymphoma, the specific cause is unknown, and it is found in lymph nodes or lymphatic tissue. It is more common in the neck, armpit and inguinal lymph nodes. Inguinal lymphoma is mostly a painless lump in the early stage, but the enlarged lump in the later stage may cause pain by pressing on the nerves, affecting activities and even causing abdominal pain. The treatment is usually based on chemotherapy and can be assisted by medications such as cetapenem and ibrutinib as prescribed by the doctor; 4. Vestibular gland cysts: they are caused by blockage of the opening of the vestibular gland, resulting in the inability of the contents to be discharged and their accumulation inside. The cysts are not obvious when they are small, but there is a lump at the vestibular perineum that can be palpated, and with the development of the disease the abscess becomes larger and may produce a feeling of falling. If the mass is large and accompanied by signs of infection, it can be treated with povidone iodine solution or potassium permanganate solution as prescribed by the doctor, or surgical methods such as laser stoma and adenotomy can be used for treatment; 5. Other: superficial skin lipomas or fibroids are mostly benign, without pressure pain, and the mass can be palpated in the groin or perineum. However, as the disease progresses, the lump may become larger and affect the activity, or even become malignant, so it should be treated in hospital in time. Women with lumps at the root of the thigh should go to the hospital in a timely manner, undergo relevant examinations, and follow the medical advice for timely treatment after diagnosis, so as not to delay the treatment.