The fibromatoses. An ultrastructural study of 31 cases.

During a five year period, thirty one cases of fibromatoses were studied with electron microscopy. A special survey was performed in relation with the proliferating cell, the extracellular space and the morphologic features of some peculiar entities as: juvenile aponeurotic fibroma, nasopharyngeal angiofibroma, recurring digital fibroma of infancy and the group of proliferative fasciitis-myositis. The main conclusions drawn of this study are: the myofibroblast is the proliferating cell of these lesions; those cells are actively synthesizing native and fibrous long spacing collagen; there are frequent intracytoplasmic inclusions of fibrous long spacing collagen; the cytoplasmic inclusions of recurring digital fibroma of infancy correspond to modifications of the cytoskeleton; and, the ganglion-like cells of proliferative fasciitis-myositis are modified myofibroblasts.