Plantar fibromatosis is a benign (non-cancerous) soft tissue tumour located at the bottom of the foot usually on top of the plantar fascia along the arch of the foot. It is also known as Ledderhose disease. Due to the location of this tumour, it may be confused with plantar fasciitis. These tumours vary in size and many are nonpainful for a long time, often until they grow large, protruding prominently under the skin. It is reported that the average size of is approximately 1.1cm and mostly demonstrates an elongated shape as opposed to a round or oval shape (Bedi & Davidson 2001). Plantar fibromatosis can often be diagnosed clinically however diagnostic imaging such as ultrasound or MRI can be helpful to confirm a diagnosis in less obvious cases (if the tumour is too small to see in a clinical setting). Diagnostic ultrasound is recommended as the imaging modality of choice due to its cost effectiveness over MRI ( Bedi & Davidson 2001).
Treatment
Not all cases of plantar fibromatosis require treatment as some cases are non-painful and can spontaneously resolve however in painful cases the most effective treatment is to offload pressure from the lesion. Pain is produced on weight bearing such as standing and walking. Most patient’s respond very well to an offloading device such as an orthosis (insole) with a deflective pad to reduce compression of the fibroma. Rarely do these lesions need to be excised (surgically removed). A small number of cases may require surgical removal, however, surgery is not without its complications. Patients may be left with painful scarring after surgical removal due to the scar line being on the bottom of the foot which can become aggravated when walking. In some cases, the fibroma tissue is embedded within the plantar fascia and foot muscles. This makes removal more difficult and can lead to damage and weakening of the plantar fascia and plantar foot muscles which can lead to secondary problems. There is also a high recurrence rate following surgical excision.
Summary
Plantar fibromatosis is a benign soft tissue mass that is often visible clinically, however in cases of smaller plantar fibroma’s that may not be seen clinically, this condition may be confused with plantar fasciitis due to the location of the tumour (on top of or within the plantar fascia). The symptom pattern of painful plantar fibromatosis may be confused with plantar fasciitis as both conditions are exacerbated by weight-bearing and relieved by rest. When suspected plantar fasciitis is not responding to usual treatment one should always consider diagnostic testing such as ultrasound which can assess the plantar fascia for thickening along with degenerative changes, which confirms plantar fasciitis. In the absence of plantar fascia thickening, the sonographer may look for other abnormalities such as a hypoechoic mass which is indicative of a plantar fibroma. Most plantar fibroma’s respond well to simple offloading with an orthosis and surgical excision should not be taken lightly for this condition.
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