An uncommon, poorly circumscribed, benign neoplasm arising in the soft tissues of infants, children and adolescents. It is characterized by the presence of haphazardly arranged spindle-shaped fibroblasts, collagenous stroma formation, and plaque-like growth pattern. There is a strong genetic component associating the neoplasm with Gardners syndrome and deep fibromatosis/desmoid tumor. [from
NCI]