Based on your description, this sounds like a condition called plantar fibromatosis (Ledderhose’s disease). Here, the plantar fascia (a layer of firm fibers under the skin in the bottom of the foot) forms hard, irregular lumps.
At first, they usually aren’t painful. But they can cause discomfort right away or later. They are not cancerous.
We don’t know what the exact cause of plantar fibromatosis is. But people with this disorder can have a similar problem in the palm of the hand. This is called palmar fibromatosis, or Dupuytren’s contracture. Some people develop this condition because of a genetic predisposition. In others, it may be secondary to:
- Plantar fasciitis (inflammation of the plantar fascia)
- Small tears in the plantar fascia with exaggerated scarring as the fascia heals, or
- A response to repetitive trauma to the bottom of the foot
Experts differ on the best way to approach this problem. Most favor the use of an orthotic to take pressure off the affected area. Other techniques include:
- Calf-stretching exercises
- Foot splints to wear at night
- Ultrasound treatments
- Local corticosteroid injections to the plantar fascia
But these are all more opinions than proven therapies.
Surgery is a last resort. When plantar fibromas are removed, it’s quite likely they will come back. But surgery may be necessary when large nodules are causing pain that can’t be relieved by other measures. Or when they compress a nerve or blood vessel.