CASE 12673 Published on 14.06.2015

Fibrous dysplasia of the mandible - A rare site of occurrence

Section

Head & neck imaging

Case Type

Clinical Cases

Authors

Dr. Akhilanand Chaurasia

Department of Oral Medicine and Radiology,
King George's Medical university
Shahmina Road, Chawk,
Lucknow, India 226003,
Email:chaurasiaakhilanand49@gmail.com
Patient

7 years, female

Categories
Area of Interest Head and neck ; Imaging Technique Conventional radiography, CT
Clinical History
A 7-year-old female patient complaining of asymmetrical swelling of the left side of the face, progressively increasing in size. No associated facial pain or numbness was described.
Imaging Findings
1. Panoramic radiograph shows unilateral fibrous dysplasia involving the left side of the mandible. The lesion involves the body, ramus, angle, coronoid and condylar process. There is lateral expansion and increased bone density extending from body to condyle and coronoid process of the left side, giving it a ‘ground glass appearance’.

2. CT shows ill-defined expansion of body, ramus, angle, coronoid and condylar process on the left side of the mandible with diffuse sclerosis and few lytic areas showing a ‘ground glass appearance’. A few foci of cortical dehiscence were noted.
Discussion
Fibrous dysplasia (FD) is a developmental bone anomaly. It is characterized by unorganized proliferation of fibrous tissue within the medullary bone leading to formation of poorly calcified and immature bone [1]. In 1891, von Recklinghausen described it as “osteitis fibrosa generalisata”. In 1938, Lichtenstein introduced the term “fibrous dysplasia”. The incidence of FD is 2.5% of all bone lesions and 7% of all benign bone tumours [2]. The most commonly involved bones are femur, tibia, ribs and facial bones. Facial and cranial bone involvement in FD occurs in approximately 50% of cases with the polyostotic form and in 10-27% of cases with monostotic form [3]. Fibrous dysplasia is twice as common in the maxilla as the mandible and the posterior part of the jaw is more frequently affected than the anterior [4]. Clinically FD is characterized by a diffuse swelling in the affected region causing facial swelling and asymmetry. Petrikowski et al suggested that in fibrous dysplasia of the mandible, upward displacement of the mandibular canal may be unique to fibrous dysplasia and could be pathognomonic [5].
Radiographic appearance of FD varies depending on the stage of development and quantity of bony matrix within the lesion. The lesion is initially more radiolucent and well-defined and gradually changes to a mottled, ill-defined radiopacity in the later stages. The radiological picture in fibrous dysplasia varies from ground glass appearance, peau d’orange, cotton wool to an amorphous, dense pattern.
A distinctive characteristic is the organization of the abnormal trabeculae into a swirling pattern similar to a fingerprint [6]. In the differential diagnosis of FD ameloblastoma, ameloblastic fibroma, ameloblastic odontoma, ameloblastic fibroodontoma, central giant cell granuloma, odontogenic cyst, ossifying fibroma, osseous dysplasia, chronic sclerosing osteomyelitis and osteosarcoma should be considered [7]. The key histologic features of fibrous dysplasia are delicate trabeculae of immature bone with no osteoblastic rimming enmeshed within a bland fibrous stroma of dysplastic spindle-shaped cells, commonly referred to as Chinese characters [8]. Treatment of fibrous dysplasia usually involves bony recontouring, modelling osteotomies, bi-maxillary osteotomies and calvarial remodelling [9, 10]. Malignant transformation of FD has been reported in less than 1% of cases [11]. Fibrous dysplasia can transform into osteosarcoma, fibrosarcoma or chondrosarcoma [12].
Differential Diagnosis List
Fibrous dysplasia of mandible
Ameloblastic fibroma
Central giant cell granuloma
Osseous dysplasia
Final Diagnosis
Fibrous dysplasia of mandible
Case information
URL: https://www.eurorad.org/case/12673
DOI: 10.1594/EURORAD/CASE.12673
ISSN: 1563-4086
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