Myofibroblasts in a collagen nevus detected by electron microscopy

A solitary collagenous connective tissue nevus on the foot of a 1-year-old infant was studied under electron microscopy. The collagen appeared normal in size, appearance, and orientation, although variable in fiber diameter. Relatively little elastic tissue was seen. The presence of myofibroblasts was notable. These large branching specialized fibroblasts were laden with highly aligned 6-8 nm microfibrils, presumably actin.