Periostitis ossificans (Garrè's osteomyelitis) radiographic study of two cases

Summary. Background.  Periostitis Ossificans (PO) is a non‐suppurative type of Osteomyelitis, commonly occurring in children and young adults, in mandible. The most common cause for PO is periapical infection of mandibular first molar. Radio graphically PO is characterized by the presence of lamellae of newly formed periosteal bone outside the cortex, giving the characteristic appearance of ‘onion skin’. Case reports.  Two male children 11 years of age reported to the Department of Oral Medicine with a painless and persistent bony hard swelling in the mandible, with a short duration ( Figs 1, 5). Both the patients had grossly decayed mandibular permanent first molar tooth with periapical infection and buccal cortical plate expansion ( Figs 2, 6). The radiographic study revealed different appearances, the Orthopantomograph of case I showed a single radiopaque lamella outside the lower cortical border, without altering original mandibular contour ( Fig. 3) and in case II showed a newly formed bony enlargement on the outer aspect of the lower cortical border without altering the original madibular contour ( Fig. 7). Occlusal radiograph of both the patients showed two distinct radiopaque lamellae of periosteal bone outside the buccal cortex ( Figs 4, 8). 1An 11‐year old boy (case 1) with a diffuse swelling of the right side of lower jaw.5An 11‐year‐old boy (case 2) with a localized swelling in the left side of mandible.2Intraoral view in case 1 showing carious right mandibular first molar with buccal expansion.6Intraoral view in case 2 showing temporary filling in carious left mandibular first molar tooth.3Orthopantomograph in case 1 showing an ill‐defined area of osteosclerosis with a periapical radiolucency of 0·5 cm in right mandibular first molar. Note a single radiopaque lamella below the lower border of mandible, separated by a fine radiolucent line.7Orthopantomograph in case 2 showing intense area of osteosclerosis in 36 region extending to lower border and a newly formed bony enlargement on the outer aspect of original cortex without altering the mandibular contour.4Occlusal view of the right mandible in case 1 showing fusiform buccal expansion extending from 46 to 48 regions with two radiopaque lamellae. Note the osteolytic area in the new bone in 46 region.8Occlusal view of the left mandible in case 2 showing buccal expansion with homogenous fine trabecular pattern and with two distinct radiopaque lamellae. Kawai et al. classified PO of mandible into type I and type II, based on whether the original contour of mandible is preserved or not. Each type is further classified into two sub types ( Table 1). In case I, the orthopantomographic appearance is characteristic of type I‐1 ( Fig. 3), but the appearance in occlusal radiograph is characteristic of type I‐2 ( Fig. 4). In case II, the appearances in both the radiographs are characteristic of type I‐2 ( Figs 7, 8). 1 Classification of PO based on the radiographic appearance [10].TYPE I (Original contour of mandible preserved) TYPE II (original contour of mandible is lost)Subtype 1 Single lamella seen as a radiopaque line of periosteal new bone overlying the original cortex separated by a radiolucent line. Newly formed bony enlargement with resorption of original cortex and osteolytic areas usually visible. Subtype 2 Visible hemi‐elliptical newly formed bony enlargement, well outlined with a thin cortical surface located on the outer aspect of original cortex producing an onion skin appearance. Deformation with a homogeneously dense osteosclerotic bone that made original cortex discernible.This subtype occasionally showed duplication of newly formed periosteal bone on the outer aspect of the deformed mandibleConclusions.  Apart from the typical onion skin appearance, PO shows various other radiographic appearances. The radiographic appearance of Periostitis Ossificans may reflect the duration, progression and the mode of healing of the disease process. The radiographic classification of PO depends on the type of radiographs taken for evaluation.