A case of osteochondroma of the coronoid process

Abstract

Jacob disease is a rare condition that affects the coronoid process. In 1899, Jacob was the first to describe osteochondroma of the coronoid process, forming a pseudoarthrosis joint between the coronoid process and the zygomatic arch. A 21-year-old man with a 7-year history of progressive limitation of mouth opening was referred to our hospital by his dentist. The maximum interincisal opening was 20 mm. A radiographic examination showed a right enlarged fungiform coronoid process. Three-dimensional computed tomography clearly demonstrated the anatomic relation between the coronoid process and the surrounding bony structure. The coronoid process was bilaterally excised by an intraoral approach. Histopathological examinations revealed compact cortical bone surrounded by a thin band of cartilage tissue diagnosed as osteochondroma, which matched the characteristics of Jacob disease. After the operation, the maximum interincisal opening was 48 mm.