Periostitis Ossificans Arising in the Mandibular Bone of a Young Patient: Report of an Unusual Case and Review of the Literature.

Periostitis ossificans, also known as Garré osteomyelitis, is a specific type of chronic osteomyelitis that forms new bone under the periosteum resulting from a periosteal reaction to chronic inflammation or infections. It commonly affects the mandible secondary to odontogenic infection. The therapeutic approach involves eliminating the infectious cause and antibiotic administration. This report describes an unusual case of periostitis ossificans arising from the mandible of an 11-year-old boy. The cause of infection was correlated with a lower right unerupted third molar, which had no obvious connection with the oral cavity. The histologic diagnosis was chronic osteomyelitis with proliferative periostitis. The patient has been followed for 1 year, without any evidence of recurrence. Periostitis ossificans can be diagnostically problematic, and various conditions must be considered in the differential diagnosis.