What is foot lump? A foot lump is a protuberance or localized area of swelling occurring on the foot. Other terms used to describe the various types of lumps include bump, nodule, contusion, tumor and cyst. Foot lumps can be caused by any number of conditions, including infections, inflammation, tumors or 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. Foot lumps due to local infectious causes may appear as boils, or abscesses. Traumatic causes of foot lumps range from bug bites to more severe injuries that can produce a localized collection of blood in the tissues (hematoma). Joint deformities can create a bump on the foot. The common bunion is a tender bump at the base of the great toe due to rotation and sideways angling of the bones that make up the great toe. Both benign and malignant tumors of the skin, soft tissues, or bones of the feet can sometimes feel like lumps. In these cases, either a biopsy or surgical removal of the foot lump can determine whether cancer is present. Cysts, which are fluid-filled, sac-like structures that can form in various parts of the body, often feel like lumps. Some cysts may be present at birth, while others develop as a result of inflammation, tumors, or wear-and-tear over time. Conditions that produce inflammation throughout the body, such as rheumatoid arthritis (chronic autoimmune disease characterized by joint inflammation), may be associated with foot lumps. Foot lumps caused by infection, inflammation or trauma are usually temporary and subside as the underlying condition resolves. Foot lumps that persist or continue to grow over time may signal more serious conditions, such as tumors. If you have a foot lump that is persistent or causes you concern, seek prompt medical care.