|Year : 2015 | Volume
| Issue : 3 | Page : 472-475
Fibrous dysplasia of maxilla: Report of two cases
Nisha Dua1, Neetu Singla2, Saloni Arora2, Shaveta Garg2
1 Department of Oral Medicine and Radiology, Sri Sukhmani Dental College and Hospital, Dera Bassi, Punjab, India
2 Department of Oral Medicine and Radiology, Guru Nanak Dev Dental College and Research Institute, Sunam, Punjab, India
|Date of Submission||15-Sep-2015|
|Date of Acceptance||19-Nov-2015|
|Date of Web Publication||25-Nov-2015|
Department of Oral Medicine and Radiology, Guru Nanak Dev Dental College and Research Institute, Bathinda-Patiala Road, Sunam - 148 028, Punjab
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Fibrous dysplasia (FD) is an idiopathic skeletal disorder in which the trabecular bone is replaced and distorted by poorly organized, structurally unsound fibro-osseous tissue. The lesion is classified into two forms: Monostotic (75-80%) and polyostotic. A distinct form of Polyostotic FD, known as McCune-Albright Syndrome, is accompanied by cutaneous pigmentation and sexual precocity, and this occurs almost exclusively in women. Typical radiographic appearance shows an expanded osseous lesion having poorly defined margins covered by a thin "eggshell" cortex and lacking periosteal new bone formation. Here, we are presenting two case reports of FD involving the maxilla.
Keywords: Fibrous dysplasia, maxilla, monostotic, polyostotic
|How to cite this article:|
Dua N, Singla N, Arora S, Garg S. Fibrous dysplasia of maxilla: Report of two cases. J Indian Acad Oral Med Radiol 2015;27:472-5
| Introduction|| |
Fibrous dysplasia (FD) is a disturbance of bone metabolism that is classified as a benign fibro-osseous lesion. The fibrous connective tissue containing abnormal bone replaces normal bone. FD is a benign intramedullary fibro-osseous lesion originally described by Lichtenstein in 1938 and by Lichtenstein and Jaffe in 1942.  It is a sporadic benign skeletal disorder that can affect one bone (monostotic form) or multiple bones (polyostotic form), and the latter may form part of the McCune-Albright syndrome (MAS) or of the Jaffe-Lichtenstein syndrome (JLS). JLS is characterized by polyostotic FD and café-au-lait pigmented skin lesions, while MAS has additional features of hyperfunctional endocrinopathies manifesting as precocious puberty, hyperthyroidism, or acromegaly.  FD is attributed to GNAS1 0(guanine nucleotide-binding protein, α-stimulating activity peptide 1) gene mutation resulting in abnormal proliferation and differentiation of pro-osteoblasts. 
| Case Reports|| |
A 16-year-old male patient reported to the Department of Oral Medicine and Radiology with the chief complaint of painless swelling on the left side of face since 3 years which started with a pea size and gradually increased to attain the present size. There was no history of trauma, paresthesia, and difficulty in chewing food, and it was not associated with any other symptoms. Extraorally [Figure 1]a, a diffuse swelling (3 × 4 cm approximately) was seen, superoinferiorly starting from 2 cm below the infraorbital margin to the line joining the commissure and the ear lobe, and mediolaterally starting from the left side of nasal septum, causing obliteration of left nasolabial fold, to ramus of mandible on the left side, which was bony hard and nontender in nature. Intraorally, the swelling extended from 24 to 27 tooth region, with expansion of the buccal cortical plate and obliteration of vestibule. Overlying mucosa was smooth and it was bony hard and nontender [Figure 1]b. Provisional diagnosis of fibro-osseous lesion of left maxillary region was made. Teeth in the vicinity of the lesion were vital. Complete hemogram showed all the parameters were within normal limits. Serological investigations including serum calcium, serum phosphorus, and alkaline phosphatase (ALP) were also within normal range.
|Figure 1: (a) Facial photograph showing asymmetry over left side of face. (b) Intraoral photograph showing swelling of left alveolar margin. (c) IOPA radiograph showing loss of lamina dura and groundglass appearance. (d) Maxillary cross-sectional occlusal view reveals homogeneous, granular radio-opacity of left maxillary alveolar bone with expansion of buccal plate. (e) OPG showing granular radio-opacity of left maxilla involving maxillary sinus. (f) PNS view showing granular radio-opacity of left maxillary sinus. (g) Histopathologic section showing features consistent with fi brous dysplasia|
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Intraoral periapical (IOPA) radiograph [Figure 1]c of 24, 25, 26, 27 revealed loss of lamina dura around the teeth and a homogeneous ground-glass radio-opaque pattern in the periapical areas. Maxillary occlusal cross-sectional view [Figure 1]d revealed homogeneous, granular radio-opacity of left maxillary alveolar bone with expansion of buccal cortical plate extending from 23 to 27, giving a granular or ground-glass appearance. On the palatal side, homogeneous radio-opacity partially covered the greater palatine foramen. Margins of the lesion blended with adjacent areas. Orthopantomograph (OPG) and paranasal sinus (PNS) view [Figure 1]e and f revealed homogeneous granular radio-opacity on the left side of maxilla involving the maxillary sinus. Surgical recontouring of maxilla was done and histopathological examination revealed a connective stroma which was cellular and fibrous with plump cells. It was intermixed with bone of varying sizes and shapes confirming FD [Figure 1]g. The histologic features were suggestive of a fibro-osseous lesion. After the clinical features and radiological features were correlated, it was diagnosed as FD.
A 26-year-old male patient reported to the Department of Oral Medicine and Radiology with the chief complaint of slowly growing painless swelling in the left upper back teeth region since 4 years. Extraorally, nothing was significant. Intraorally, the swelling started with the size of a pea and gradually increased to attain the present size over a period of time. There was no history of trauma, paresthesia, and difficulty in chewing food, and it was not associated with any other symptoms. On palpation, the consistency was bony hard and nontender and there was no local rise of temperature. The swelling involving the left maxillary alveolar bone extended from 24 to 28 with expansion of buccal and palatal cortical plates and obliteration of the buccal vestibule [Figure 2]a. Overlying mucosa appeared normal, firm, and was nontender. Teeth surrounding the lesion were vital. Provisional diagnosis of fibro-osseous lesion of left maxilla was made. Complete hemogram showed normal parameters except raised erythrocyte sedimentation rate (ESR). Serological investigations including serum calcium, serum phosphorus, and ALP were within normal range.
|Figure 2: (a) Intraoral photograph showing swelling of left alveolar margin. (b) IOPA radiograph showing loss of lamina dura with groundglass appearance of bone. (c) Maxillary cross-sectional occlusal reveals homogeneous, granular radio-opacity of left maxillary alveolar bone with expansion of buccal plate extending from 23 to 27 teeth region. (d) OPG showing granular radio-opacity on the left side of maxilla involving maxillary sinus. (e) PNS view showing maxillary sinus obliteration on the left side. (f) Histopathologic section showing bony trabeculae resembling Chinese characters in the connective tissue|
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IOPA radiograph [Figure 2]b of 24, 25, 26, 27 revealed loss of lamina dura around 24, 25, 26, 27 and a homogeneous granular radio-opaque pattern in the periapical areas. Supraeruption of 26 was also seen. Maxillary cross-sectional occlusal radiograph [Figure 2]c revealed homogeneous, granular radio-opacity of left maxillary alveolar bone with expansion of buccal plate extending from 23 to 27, giving a granular or ground-glass appearance. Margins of lesion blended with the adjacent areas. OPG and PNS view [Figure 2]d and e revealed homogeneous granular radio-opacity causing obliteration of the maxillary sinus. OPG also revealed that 26 was present below the occlusal line with proximal caries. The lesion was surgically excised and histopathology of the excised tissue showed a benign fibro-osseous lesion formed by a hypercellular fibroblastic stroma consisting of spindle cells arranged in whorls with storiform pattern and also in loose sheets with intervening collagen. Among these was immature woven bone with Chinese letter configuration. These features were suggestive of FD [Figure 2]f.
| Discussion|| |
FD is commonly a benign lesion in which irregularly distributed spicules of bone lie in cellular fibrous stroma. The lesion is believed to be hamartomatous developmental abnormality of bone.  FD is essentially a disease of young population with incidence of 1:4000 to 1:10,000.  Bones of face and skull are frequently involved, resulting in asymmetry and spontaneous fractures. Craniofacial structures are involved in 10% of monostotic type, 50% of mild polyostotic cases, and 100% of severe polyostotic cases. Maxilla and mandible are commonly affected with the temporal bone involved in 18% of cases.
Reed's definition states that FD is an arrest of bone maturation and presence of woven bone with ossification resulting from metaplasia of a nonspecific fibro-osseous type.  In FD bone is actually replaced by fibrous tissue.  It commonly presents as an asymptomatic, unilateral, and slowly progressive enlargement of involved jaw. Fusiform swelling generally involves buccal cortical plate with displacement of teeth resulting in malocclusion.  The exact cause of FD is not known. It is classified by WHO as developmental in origin. The condition is not thought to be hereditary. The etiology has been linked with a mutation in the Gsα gene located at chromosome 20q13.2-13.3. The specific location of the mutation is at position 201, which is usually occupied by arginine (R201) and is replaced by either a cysteine (R201C) or a histidine (R201H). 
The GNAS1 gene encodes a G-protein that stimulates the production of cAMP. The mutation results in the continuous activation of the G-protein leading to overproduction of cAMP in affected tissues. Hyperfunctioning of affected endocrine organs frequently gives rise to precocious puberty, hyperthyroidism, growth hormone excess, and overproduction of cortisol.  There is increased proliferation of melanocytes resulting in large café-au-lait spots. cAMP is thought to have effect on the differentiation of osteoblasts leading to FD. 
Its onset is usually insidious, although recurrent bone pain is the most common presenting skeletal symptom. But, in contrast, this feature was not present in the cases presented here. There is an evidence of bowing, and deformity or thickening of long bones, often unilateral in distribution. FD of craniofacial complex may differ both radiologically and histologically from its counterparts in the axial skeleton.  FD appears frequently in axial as a circumscribed radiolucency with thin sclerotic periphery, whereas cases of craniofacial FD, especially those affecting the jaws and adjacent bones, are poorly defined and more radio-opaque. A reason for the difference in appearance between maxillofacial FD and FD of long bones is that the former occurs in skeleton derived from membranous bone.
Fries has described three radiological patterns in craniofacial FD. , The first is pagetoid or ground glass with bone expansion and alternate areas of radiodensity and radiolucency. It occurs in more than half of the patients, most of whom are older than 30 years of age and have had symptoms for an average of 15 years. The second pattern is sclerotic, with bone expansion and a homogenous radiodensity. The third type is cyst-like, usually a round or oval lesion with a sclerotic border. The sclerotic and cyst-like patterns occur in younger individuals (age below 20 years). Other features include fingerprint bone pattern, orange peel appearance, and superior displacement of mandibular canal in mandibular lesion.  Skeletal radiographic features include "shepherd's crook" deformity of femoral neck and "bowing deformities" in weight-bearing long bones.
In most cases, the radiographic and clinical findings are sufficient to allow the practitioner to diagnose without a biopsy. Differential diagnoses with similar radiographic appearance, such as ameloblastoma, ameloblastic fibroma, ameloblastic odontoma, ameloblastic fibro-odontoma, central giant cell granuloma, odontogenic cyst, ossifying fibroma, osseous dysplasia, chronic sclerosing osteomyelitis, and osteosarcoma, should be considered.  The density and trabecular pattern of FD lesions is variable. Early lesions may be more radiolucent than mature lesions and, in rare cases, may appear to have granular internal septa, giving the internal aspect a multilocular appearance. The abnormal trabeculae are usually shorter, thinner, irregularly shaped, and more numerous than the normal trabeculae. This creates a variable radio-opaque pattern. It may have a granular appearance ("ground-glass" appearance, resembling the small fragments of a shattered windshield), a pattern resembling the surface of an orange (peau d'orange), a wispy arrangement (cotton wool), or an amorphous, dense pattern. A distinctive characteristic is the organization of the abnormal trabeculae into a swirling pattern similar to a fingerprint. 
Routine investigations include complete hemogram and levels of serum calcium, serum phosphorus, and serum ALP. Serum ALP is occasionally elevated, but calcium, parathyroid hormone, 25-hydroxyvitamin D, and 1,25-dihydroxyvitamin D levels are normal in most cases of FD. Persons with extensive polyostotic FD may have hypophosphatemia, hyperphosphaturia, and osteomalacia. Premature secretion of pituitary follicle stimulating hormone is found. There may be an elevated basal metabolic rate.  The microscopic appearances are those of a hypercellular and cytologically uniform fibrous stroma within which delicate and irregularly shaped trabeculae of woven bone are deposited. The configurations of these bony trabeculae are often referred to as resembling Chinese characters. 
Malignant changes with FD include osteosarcoma, fibrosarcoma, chondrosarcoma, and Ewing's sarcoma.  Useful biomarkers such as serum ALP and urinary hydroxyproline can be used to monitor response in nonsurgical treatment of the disease rather than diagnosis.  Hormone treatment includes calcitonin and pamindronate. Chapurlat et al. (1997) reported that patients treated with bisphosphonate pamindronate show less bone pain, the number of painful sites is also reduced, and there is significant improvement of radiographic lesion. Surgery is the primary treatment of choice, which usually consists of conservative "recontouring" of tooth-bearing area of jaw.  But surgical treatment for cranio-maxillo-facial lesions is controversial. Excision of all the affected bone is usually fruitless since it is impossible to be sure of the limits of the disease. However, it is only indicated if an important function is threatened, deformity becomes substantial, or complications develop. 
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
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Conflicts of interest
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[Figure 1], [Figure 2]