How are you? Can you elaborate on the lump's location or characteristic? This could be due to plantar fibromatosis which are mostly benign growths that occur on the bottom of the foot.The plantar fascia is a thick, broad, inelastic band of fibrous tissue that is found along the bottom of the foot.Plantar fasciitis refers to an inflammation of the plantar fascia and can be the result of some type of injury such as from repeated trauma to the tissue. Treatment that may help include anti-inflammatory mediation, icing, stretching, activity modification, and heel inserts. If the lump persists, you need to have this checked by your doctor for proper evaluation. Direct clinical examination is important and a biopsy may also be done to rule out malignancy. Take care and regards.