A plantar fibroma is a mass that develops under the skin along the bottom of the foot. It is essentially a non-cancerous tumor made up of cartilage and other soft tissues. Most plantar fibromas are harmless and do not cause symptoms or major health problems. If there are multiple tumors or a fibroma grows very large, however, a person may have difficulties walking or chronic aches and tenderness in the affected foot. A doctor can assess a symptomatic plantar fibroma and determine whether or not treatment in the form of medications or surgery is necessary.
It is not clear what causes a plantar fibroma to develop. Tumors arise from the band of elastic connective tissue called the plantar fascia that supports the arch of the foot. Many doctors believe that recurring injuries to the plantar fascia, as can occur with high activity levels or wearing inappropriate footwear, may precede fibroma development. Fibromas are more common in males than in females, and most people who develop them are middle-aged or elderly.
Plantar fibromas are usually very small and asymptomatic. Even large lumps are usually painless, though they may become noticeable when wearing tight shoes or standing barefoot. A fibroma can become irritated and inflamed with excessive walking or running, which may result in redness, tenderness, and swelling around the mass. It is important to visit a doctor whenever chronic foot pain or an unusual bump is present to receive an accurate diagnosis and learn about possible treatment options.
In most cases, a physician can diagnose a plantar fibroma by simply feeling the lump in the foot and asking about symptoms. A fibroma is usually firm to the touch and can be moved around slightly underneath the skin. Imaging scans may be taken in some cases to look for underlying damage to the plantar fascia band and to determine the exact size of the tumor.
A plantar fibroma that does not cause symptoms does not normally require treatment. The doctor may simply suggest keeping an eye on the mass to make sure it does not grow larger in the future. If pain and inflammation are present, the physician may inject the foot with a corticosteroid or prescribe a topical anti-inflammatory cream. He or she might also suggest investing in more comfortable shoes or cushioning inserts to help take pressure off of the bottoms of the feet.
Surgery is only necessary if fibromas become very large and painful. An experienced surgeon can carefully remove the mass from the plantar fascia and repair the surrounding tissue. Patients who undergo surgery usually need to rest their feet for at least two weeks and then attend physical therapy sessions to ensure complete recoveries.