What is a thigh lump? A thigh lump is a bulge, bump, nodule, contusion, tumor, or swollen area on your thigh. Lumps can be caused by any number of conditions, including infections, inflammation, tumors and trauma. Depending on the cause, lumps may be single or multiple, soft or firm, painful or painless. They may grow rapidly or may not change in size. You may also have other symptoms, depending upon the cause of your thigh lump. Thigh lumps due to infectious causes in or near your leg may appear as boils or abscesses. Traumatic causes of thigh lumps can include minor injuries such as bug bites or severe injuries that can produce a localized hematoma (collection of blood in body tissues). Although these are rare causes, both benign and malignant tumors of the skin, soft tissues, or bones can appear as lumps on the thigh. In these cases, either a biopsy or surgical removal of the lump can determine whether cancer is present. A thigh lump can be a sign of injury and require emergency care. It may in some cases be accompanied by serious injuries to the leg. Seek immediate medical care (call 911) for serious symptoms, such as paralysis or inability to move a body part, loss of sensation, absent pulses in your feet, uncontrolled or heavy bleeding, or uncontrollable pain. If your thigh lump persists or causes you concern, seek prompt medical care.