Plantar Fibromatosis in a Mentally Challenged Man Treated with Intralesional Corticosteroids.

A 21-year-old mentally challenged man presented with a fixed plaque lesion on the right foot, which had been present for 10 years. Dermatologic examination revealed an erythematous, painful, firm, fixed plaque-nodular lesion on the plantar aspect of the right foot (Figure 1A). Nothing of distinction was noted from his family history or his laboratory tests. An incisional biopsy revealed parallel, regular bundles composed of uniform, plump spindle cells. Thin collagen fibers were seen in contact with and located between the spindle cells. This mass was separated from the surrounding soft tissue by an irregular, unclear border (Figure 2A). İmmunohistochemically, the spindle cells showed diffuse, strong reactivity to vimentin (Figure 2B) and smooth muscle actin.