Plantar fibromatosis is a fibrotic tissue disorder of the plantar fascia that consists of excess collagen or fibrotic tissue. The excess collagen is commonly referred to as a fibroma. It is most commonly located in the arch of the foot in a tissue layer called the plantar aponeurosis. The two most common symptoms of plantar fibromatosis are firm nodules that can be felt just under the skin and pain that can be constant or increases when standing or walking. Plantar fibromas often increase in size and density over time but not indefinitely.