[Aggressive chondroblastoma]

The authors report three observations of rather extensive aggressive chondroblastoma and draw attention to difficulties of histological diagnosis, which result out of a less typical histological picture, in which signs of differentiation into cartilaginous tissue may be missing. Differential diagnosis may be facilitated by proper recognition of the cytologic character of chondroblasts by the positivity of S-100 protein, and by proving characteristic properties of chondroblasts in electronmicroscopic examination. In treating this type of tumors an increased risk of local recurrence (in one of our patients) and aggressive behaviour to surrounding tissues should be considered, exceptionally pulmonary metastases may develop, as was the case in one of our presented patients.