Introduction

Definition

Ossifying fibroma and fibrous dysplasia are both benign fibro-osseous lesions of the oral cavity.¹ Ossifying fibroma is a slow-growing, well-circumscribed, benign tumour of the bone that arises from the cells of the periodontal ligament.² Fibrous dysplasia is a condition in which the replacement of the bone with fibro-osseous tissue takes place.³

Importance of distinguishing between ossifying fibroma and fibrous dysplasia

It is important to distinguish between the conditions for appropriate clinical management, prognosis assessment, and guidance for treatment and follow-ups. Each condition has its own clinical presentations, radiographic findings, histopathological features, management and treatment options.¹

Etiology

Ossifying fibroma

The etiology of the condition is unclear. It is mostly believed that it is associated with trauma and inflammation. There is no evidence regarding a specific gene mutation.²

Fibrous dysplasia

It is characterised by the replacement of bone with fibrous tissue. It usually starts in childhood, progresses slowly with the enlargement of the bone, which eventually ceases with puberty. The pathogenesis is related to the GNAS (guanine nucleotide-binding protein, alpha-stimulating) gene mutation. It results from an abnormality in the development of bone-forming mesenchyme.¹

Epidemiology 

Ossifying fibroma 

It is a rare lesion, and occurs mainly during the third to fourth decade of life. The female predilection is more than that of males (5:1).¹ White people are more commonly affected than black.

Fibrous dysplasia

It is a rare lesion and can occur in any age group. Children and adults are most commonly affected. There is no gender predilection. It is more common in the skull and facial bones (with the maxilla being the most affected area).¹ It starts in childhood, with a slowly progressive enlargement of bone that generally slows and ceases with puberty.²

Clinical presentation 

Ossifying Fibroma v/s Fibrous Dysplasia are both conditions that affect the bone, but their different clinical features are as follows:-

_1,2,3 

Radiographic features

Ossifying fibroma

• Well-defined margin with radiopaque lesion
• Moderate cortical expansion
• Osteoblastic rimming²

Fibrous dysplasia

• Classic ground glass appearance is seen
• Varying degrees of radiopacity and lucency depending upon the amount of calcified material present¹

Histopathological features

• Ossifying fibroma is histologically composed of varying amounts of osteoid, rounded cementoid calcifications and bone. Fibrous dysplasia is described as gritty or sandy
• Fibrous dysplasia is histologically composed of irregular, randomly oriented bony trabeculae.  Increased alkaline phosphatase, especially when a tumour is growing. Endocrine abnormalities can also be seen¹ 

Treatment

Both conditions involve surgical excision with curettage. 

Ossifying fibroma has a poor prognosis and, due to its aggressive behaviour, has a greater propensity for recurrence.

Fibrous dysplasia

If fibrous dysplasia is mild and does not cause any pain or discomfort, the best treatment is to wait and watch. Regular monitoring with imaging studies can help to keep track of time.

Pain relievers such as acetaminophen and NSAIDS can be given.³

Bisphosphonates are used to relieve bone pain and slow down bone turnover by inhibiting osteoclast activity.

Surgery and curettage are needed when fibrous dysplasia becomes aggressive and causes severe symptoms such as bone fractures, deformities, and nerve compression.¹

Summary

Ossifying fibroma and fibrous dysplasia are both bone conditions but differ in occurrence, location, radiographic appearance and clinical presentation. Ossifying fibroma primarily affects the jawbone, while fibrous dysplasia mostly affects the long bones and shows a ground-glass appearance radiographically. Both conditions require imaging and biopsy for accurate diagnosis and appropriate management.¹ Treatment options depend on the severity of the condition. Mostly in fibrous dysplasia, as long bones are involved, the chances of pain and bone fractures increase. Treatment includes surgical removal and curettage. Medications are given in order to reduce pain and may be followed by bisphosphonates to reduce bone turnover. 

FAQs

Who can get ossifying fibroma?

It occurs in adults of the age group 30-40, and females are more common.

Is ossifying fibroma cancerous?

Ossifying fibroma and fibrous dysplasia are both benign non-cancerous

What is the treatment for fibrous dysplasia?

The treatment depends on the severity and location of the symptoms. Options include surgery, medications to reduce pain, and bisphosphonates to slow bone turnover.

What is the treatment for ossifying fibroma?

Surgical excision is often recommended, especially when the tumour is causing more pain and discomfort 

What is the prognosis of ossifying fibroma?

Ossifying fibroma is really aggressive in nature and has a tendency to recur.