Abstract
BackgroundBoth mandibular condylar hyperplasia and condylar osteochondroma can lead to maxillofacial skeletal asymmetry and malocclusion, although they exhibit different biological behavior. This study attempted to compare the histological features of mandibular condylar hyperplasia and condylar osteochondroma using hematoxylin-and-eosin (H&E) staining, and immunohistochemistry staining of PCNA and EXT1 with quantitative analysis method.ResultsThe H&E staining showed that condylar hyperplasia and condylar osteochondroma could be divided into four histological types and exhibited features of different endochondral ossification stages. There was evidence of a thicker cartilage cap in condylar osteochondroma as compared condylar hyperplasia (P = 0.018). The percentage of bone formation in condylar osteochondroma was larger than was found in condylar hyperplasia (P = 0.04). Immunohistochemical staining showed that PCNA was mainly located in the undifferentiated mesenchymal layer and the hypertrophic cartilage layer, and there were more PCNA positive cells in the condylar osteochondroma (P = 0.007). EXT1 was mainly expressed in the cartilage layer, and there was also a higher positive rate of EXT1 in condylar osteochondroma (P = 0.0366). The thicker cartilage cap, higher bone formation rate and higher PCNA positive rate indicated a higher rate of proliferative activity in condylar osteochondroma. The more significant positive rate of EXT1 in condylar osteochondroma implied differential biological characteristic as compared to condylar hyperplasia.ConclusionsThese features might be useful in histopathologically distinguishing condylar hyperplasia and osteochondroma.
Highlights
Both mandibular condylar hyperplasia and condylar osteochondroma can lead to maxillofacial skeletal asymmetry and malocclusion, they exhibit different biological behavior
Patient information The diagnosis of condylar osteochondroma and condylar hyperplasia were made by experienced maxillocraniofacial surgeons, radiologists and pathologists, and diagnoses were based on the clinical symptoms, computed tomography (CT) scanning characteristics and H&E staining (Fig. 1)
Our study showed that the mean age of patients in the condylar osteochondroma group was 32 ± 10.2 years of age and 26 ± 4.8 years of age in hyperplasia group, which can be inferred that older facial asymmetry patients might suffer from condylar osteochondroma
Summary
Both mandibular condylar hyperplasia and condylar osteochondroma can lead to maxillofacial skeletal asymmetry and malocclusion, they exhibit different biological behavior. Osteochondroma is described as osteocartilaginous exostosis [1] It is considered the most common tumor of skeletal bones, comprising approximately 35 to 50% of all benign bone tumors [2], but it is rarely found in the jaw [3]. Yu et al Orphanet Journal of Rare Diseases (2019) 14:293 these methods present with inherent limitations, and the cell behavior based on pathological information is still considered the definitive choice for diagnosis. Studies of the pathogenesis and molecular biology of mandible condylar hyperplasia and condylar osteochondroma currently remain at an initial stage of investigation, and the qualitative H&E staining results showed no characterized cell behavior between these two diseases [10]
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