Garre’s osteomyelitis, also referred to as chronic sclerosing osteomyelitis or proliferative periostitis, is an uncommon form of chronic osteomyelitis primarily observed in children and adolescents. The disease exhibits no clear sex predilection and has an estimated annual incidence of around 13 per 100,000 individuals, although this figure may be underreported due to its indolent progression and non-specific clinical features. This condition was first described in 1893 by Carl Garre, a Swiss surgeon, who documented the sclerotic and proliferative response of the periosteum to persistent low-grade infection or chronic irritation.[1]

Garre’s osteomyelitis is characterized by a chronic inflammatory reaction in the bone, leading to a unique pattern of subperiosteal new bone formation. Unlike acute osteomyelitis, which presents with suppuration and systemic signs of infection, Garre’s variant evolves slowly and is typically non-suppurative. It is often associated with dental infections such as periapical periodontitis, periodontal disease, or complications from dental caries. The offending pathogens stimulate a low-grade inflammatory response, which triggers the periosteum to deposit successive layers of new bone in an effort to wall off the infection.[2]

The mandible is the most frequently affected bone, likely due to its dense cortical structure, relatively poor vascularity, and common exposure to odontogenic infections. Radiographically, the condition is notable for a layered “onion-skin” appearance of the periosteal reaction, though this may vary depending on the stage and chronicity of the disease.[3]

In 1955, Pell et al. were among the first to document a case of Garre’s osteomyelitis involving the mandible, thereby establishing its clinical significance in the context of maxillofacial infections. Since then, although rare, several cases have been reported across different age groups and anatomical sites, with the majority involving the lower jaw. Early diagnosis is essential to prevent complications and avoid unnecessary surgical interventions.[1,2]

This case report presents an unusual manifestation of Garre’s osteomyelitis with a focus on its clinical presentation, radiographic findings, histopathological features, and management challenges, thereby contributing to the limited but growing literature on this rare entity.

A 14-year-old male presented to the Pediatric Outpatient Department with a primary complaint of progressive swelling over the left cheek accompanied by noticeable facial asymmetry (Figure 1). The swelling was initially sudden in onset and had gradually increased in size over time. On physical examination, the swelling was found to be bony hard, non-tender, and fixed to the underlying structure, suggesting an underlying skeletal pathology rather than soft tissue involvement.

The patient’s history revealed a preceding episode of dental caries involving the first deciduous molar of the left mandible, which eventually exfoliated. Following this, the patient experienced a painful eruption of the corresponding permanent tooth, which was initially managed symptomatically. An occlusal radiograph of the mandible revealed a classical “onion-skin” appearance of the periosteum (Figure 2), which is considered pathognomonic for chronic sclerosing osteomyelitis, particularly Garre’s osteomyelitis.

Over the past three years, the patient had multiple recurrences of similar swelling, approximately ten episodes in total, causing considerable distress. During this period, he was evaluated by both Dentistry and Rheumatology departments in view of the recurrent nature of the swelling and concerns regarding possible autoimmune or systemic inflammatory conditions. However, systemic evaluations, including complete blood counts, ESR, CRP, and autoimmune profile, remained within normal limits, ruling out rheumatological or systemic infectious etiologies.

In our hospital, a contrast-enhanced CT (CECT) scan of the head and neck was conducted (Figure 3), which confirmed the presence of chronic osteomyelitis of the mandible. The radiological findings showed irregular bony thickening of the mandibular cortex with periosteal new bone formation and no signs of suppuration or necrosis, which strongly favored the diagnosis of Garre’s osteomyelitis.

Based on the clinical, radiological, and historical findings, a definitive diagnosis of chronic sclerosing osteomyelitis (Garre’s osteomyelitis) was made, attributed to a long-standing low-grade odontogenic infection originating from the root of the previously carious molar.

The patient underwent surgical extraction of the offending permanent tooth, along with gingival curettage to eliminate residual sources of infection. He was started on a course of broad-spectrum oral antibiotics, targeting common oral flora, including anaerobes. Postoperatively, the patient reported substantial relief in pain and swelling, with improvement in facial symmetry over subsequent follow-ups.

For residual discomfort, he was prescribed non-steroidal anti-inflammatory drugs (NSAIDs), specifically Naproxen, and was advised to remain under regular clinical follow-up to monitor for potential recurrence or need for further surgical intervention. At present, the patient remains clinically stable, with no new episodes of swelling or pain, indicating a favorable response to the treatment.

Figure 1 (a,b)- patient presenting with left cheek swelling and facial asymmetry

Figure 2- Occlusal Radiograph

Figure 3- CECT Head and Neck

Management:

The main treatment goal is to eliminate the etiological factor- most commonly by the extraction of the offending/ causative tooth. In this case, endodontic intervention ( tooth extraction with gingival curettage )was done as the tooth was restorable and the patient parent’s were hesitant for surgical extraction. There is no need for biopsy during diagnosis, except when the cause is unknown . Usually, radiographic findings or CT are sufficient.

Garre’s osteomyelitis, also known as chronic sclerosing osteomyelitis with proliferative periostitis, is a rare and distinctive form of chronic osteomyelitis that primarily affects the jawbones, particularly the mandible. It is characterized by a localized periosteal thickening, triggered by persistent low-grade irritation or chronic odontogenic infection. The condition typically occurs in children and adolescents, owing to the high osteogenic potential of the periosteum in this age group.

Pathophysiologically, the condition arises when a low-virulence infection, often odontogenic in origin (e.g., dental caries, periapical abscesses, or periodontal disease), extends from the spongiosa of the bone to the periosteal layer. This stimulates a defensive reparative response by the periosteum, leading to layered deposition of new bone along the cortex. While the inciting stimulus is often infectious, the actual clinical manifestation of Garre’s osteomyelitis depends on a complex interplay of local and systemic factors—including the virulence of the infecting organisms, host immune response, local blood supply, and critically, osteoblastic activity of the periosteum.[4,5,6]

Interestingly, in some cases, the etiopathogenesis may remain idiopathic, with no clear infectious trigger identified. Regardless, the resultant new bone formation produces a characteristic “onion-skin” radiographic appearance, which serves as a diagnostic hallmark. However, this radiologic finding is not pathognomonic, as it can also be seen in other bone pathologies, including Ewing's sarcoma, osteosarcoma, and fibrous dysplasia, thereby complicating diagnosis and potentially leading to misclassification.[6]

Although Garre’s osteomyelitis is well recognized in dental and maxillofacial literature, its diagnosis remains challenging due to its non-specific clinical presentation and overlapping radiological features with more aggressive bone pathologies. As a result, diagnostic dilemmas frequently arise, making treatment planning and clinical decision-making difficult. The absence of systemic signs of infection, such as fever or elevated inflammatory markers, often leads to underrecognition of this chronic inflammatory condition.[7,8]

From a histological perspective, the lesion demonstrates chronic inflammatory infiltrates, new bone trabeculae, and fibrosis, consistent with a long-standing inflammatory stimulus. However, histopathological confirmation is not always required for diagnosis, especially when the clinical and radiological findings are classic.[8]

The rarity of this disease can be attributed to the need for a unique combination of factors for its development: a chronic, low-grade infection, typically from an odontogenic source, and a periosteum that retains significant osteoblastic activity, as is often seen in younger individuals. In adults, due to decreased periosteal activity, the same low-grade stimulus may not elicit similar bony proliferation.[4,5,8]

Management of Garre’s osteomyelitis is usually conservative, aimed at eliminating the source of infection, typically through dental extraction, endodontic therapy, or gingival curettage, followed by appropriate antibiotic therapy. In most cases, resolution of the offending stimulus leads to gradual regression of the periosteal reaction, and surgical recontouring of the bone is rarely required unless there is persistent cosmetic deformity.[7,8]

In this case, the patient experienced multiple recurrences over three years, highlighting the chronicity and persistence of the condition when the etiological source remains untreated or inadequately addressed. Once the offending tooth was extracted and local infection controlled, the symptoms improved significantly, reinforcing the importance of early diagnosis and definitive removal of the infection source in preventing long-term morbidity.

To conclude, Garre’s osteomyelitis remains a challenging but important diagnosis, particularly in the pediatric population presenting with unilateral bony swelling of the jaw. A high index of suspicion, combined with clinical, radiographic, and occasionally histologic correlation, is essential to differentiate it from more aggressive lesions and to guide timely and appropriate treatment.

Intriguing case of chronic osteomyelitis involving the mandible which is served as separate entity when compared to osteomyelitis in other parts of the body. Prolonged clinical course, characterized by intermittent periods of exacerbation followed by improvement and slowly progressive swelling. Mimicking other new bone formation pathological  conditions, creating dilemma.

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