Histopathological and scintigraphic features of condylar hyperplasia.

This investigation was undertaken to correlate the scintigraphic and histological features of condylar hyperplasia to identify consistent diagnostic findings. A series of 34 surgically excised condyles were examined from a 5 year period. Of these, 20 were diagnosed clinically and histologically as condylar hyperplasia. In 18 of these the presentation was one of increasing facial asymmetry. In all 20 cases there was an increased uptake of Technetium 99 as determined by gamma scintigraphy. The thickness of the fibrous articular layer, undifferentiated germinal mesenchyme layer and the hyperplastic cartilage layer were measured using an eyepiece graticule and the presence and frequency of islands of cartilage in the subchondral bone were noted. 7 patients received tetracycline hydrochloride 14 and 4 days pre-operatively in an attempt to quantify the calcification rate. An uninterrupted layer of undifferentiated germinal mesenchyme is a consistent feature of condylar hyperplasia. An increased uptake on scintigraphy is proportionally related to the thickness of the hypertrophic cartilage and not only to the presence but also the frequency of cartilage islands in the subchondral bone.