What is a Plantar Fibroma
A plantar fibroma is a benign knot consisting of fibrous tissue embedded in the plantar fascia, in the arch of the foot.

Signs and Symptoms
The most noticeable sign of a plantar fibroma is a lump in the arch of the foot that is firm to the touch. It can stay the same size or become larger, and additional fibromas can develop. People with a plantar fibroma may or may not experience pain. if pain does occur, it is usually caused by shoes pushing against the lump in the arch. 

Diagnosis
Your podiatrist will examine the foot in question and press on the affected area. An MRI or biopsy may be performed to rule out any other causes and aid in the diagnosis.