Lederhose's disease is a condition that can cause the formation of painful bumps on the bottom of the foot. Lederhose's disease is often confused with other problems involving the sole of the foot, such as corns or benign tumors, all of which can cause nodules to form in the sole of the foot. In the case of Lederhose's disease, the layer of tissue beneath the skin forms tight nodules of tissue called fascia. No one knows exactly why the nodules form, but the condition is closely related to Dupuytren's contracture
in the hand.
Benson LS, et al. "Dupuytren's contracture" J. Am. Acad. Ortho. Surg., Jan 1998; 6: 24 - 35.