[Fibroma of the tendon sheath. Diagnosis and differential diagnosis]

Ten cases of fibroma of the tendon sheath were examined by means of histological, topochemical, and immunohistochemical methods. Investigations were aimed at re-evaluation of histological variability and definition of diagnostic criteria. Microscopic observations suggested the following features to be typical of fibroma of the tendon sheath: Primitive mesenchymal or fibroblastic cells without further differentiation, slit- and cleft-like spaces with lining cells decorated by endothelial markers, and collagenous, cartilaginous or myxoid basic substance at least in areas rich with sulphated glycosaminoglycans. Differential diagnostic distinction of tendon sheath fibroma from myxoid cartilage tumors, fasciitis nodularis, and myxoid fibromatosis as well as from fibrohistiocytic lesions and giant cell tumors of tendon sheath is discussed with reference to the above definition.