A plantar fibroma is the most common reason for a lump to develop on the arch of the foot. These are often small (less than half an inch), but can grow steadily to reach sizes of 2 inches or more. They may occur as a single lesion or they may present as multiple lesions, typically along the medial border of the plantar fascia. They are benign and are composed of dense, fibrous tissue. Many patients with plantar fibromas do not have any symptoms and when they do, it is often only a vague discomfort from “walking on a lump”. These masses can be treated non-surgically with a custom or soft accommodating prefabricated (over the counter) orthotic. However, if they grow larger or are a persistent source of discomfort, they should be removed surgically.
Patients with plantar fibromas will usually report that they “just noticed the mass one day”. Occasionally they will have a history of a similar mass in the palm (Dupytren’s Contracture). As the mass gets larger, they may report increasing discomfort with prolonged standing.
Plantar fibromas are usually located on the inside of the arch of the foot. They usually feel smooth and rubbery. They are not usually tender to touch, although they may become irritated with prolonged walking.
X-rays are often negative, although if the x-rays are taken in such a way as to highlight the soft-tissues, an outline of a mass may be seen.
An MRI will show a smooth, consistent (homogenous) mass that is affiliated with the plantar fascia. An MRI will confirm the diagnosis and allow differentiation of other causes of masses in the foot, such as lipomas, ganglions, neuromas, herniations of the plantar fasica, and tumors (very rare).
Plantar fibromas are typically treated non-operatively, until they cause discomfort to the patient on a regular basis. Non-operative treatment includes:
Operative treatment is typically avoided due to both the high recurrence rate and the difficulty with obtaining clear margins. Operative treatment involves excising (cutting out) the mass. This is typically done through an incision in line with the length of the foot. The mass is then sent to be examined by the pathologist to confirm the diagnosis.
Surgery to remove a plantar fibroma can be associated with the usual array of potential complications, including: