Clinical and radiological features of Jacob’s disease. A case report involving an osteochondroma of the coronoid process

Introduction: A large number of disorders affecting the masticatory system can cause mouthopening restrictions. Among them is Jacob’s disease, characterized by restricted jaw movements and caused by pressure of the mandible coronoid process, which is longer than normal in size, on the posterior aspect of the zygomatic arch, together establishing new joint formation. Observation: We present a case report of a 29-year-old male patient presenting limited mouth opening. Inter-incisal maximum mouth opening was 5 mm. On panoramic radiograph an elongated coronoid process of the mandible was evident. Computed tomography (CT) scans showed the relationship between the exophytic mass and the inner surface of the zygomatic arch. An extra-oral coronoidectomy was performed. A mouth opening of 55 mm was achieved intra-operatively. The post-operative period was without complications. The histopathological diagnosis was osteochondroma. Discussion: The clinical, radiological and histopathological characteristics and surgical approach to Jacob’s disease are discussed. Conclusion: In a patient with a limitation of mouth opening, and without any temporo-mandibular joint disease, an examination of the coronoid process is required to identify hypertrophy ofthe coronoid process and to diagnose Jacob’s disease