|Year : 2015 | Volume
| Issue : 2 | Page : 237-240
Fibrous dysplasia of bone causing unilateral proptosis
Reshma Ramakrishnan, Saurabh Shrivastava, Anamika Patel, Anjaneya Agashe
Department of Ophthalmology, MGM Hospital, Kamothe, Navi Mumbai, Maharashtra, India
|Date of Web Publication||13-Mar-2015|
N 601, Haware Splendor, Sector 20, Khargar, Navi Mumbai - 410 210, Maharashtra
Source of Support: None, Conflict of Interest: None
Fibrous dysplasia (FD) is a slow growing benign noninherited disorder in which normal bones are replaced by fibrous tissue and immature woven bones. Here we report a case of 30-year-old female who presented with unilateral proptosis and lagophthalmos without any visual loss; was diagnosed with polyostotic FD. Patient was taken up for surgery. Osseous reconturing was done by shaving of involved facial bones. Postoperatively, there was a decrease in proptosis and lagophthalmos.
Keywords: Fibrous dysplasia, lagophthalmos, proptosis
|How to cite this article:|
Ramakrishnan R, Shrivastava S, Patel A, Agashe A. Fibrous dysplasia of bone causing unilateral proptosis. Med J DY Patil Univ 2015;8:237-40
| Introduction|| |
Fibrous dysplasia (FD) is an abnormal bone growth where normal bone is replaced with fibrous tissue. It can occur in any part of the skeleton but bones of skull, thigh, shin, ribs upper arm, and pelvis are commonly affected. FD can be monostotic with lesions localized in only one bone, (70-80% of all cases), or it can be polyostotic in which it involves many bones. We present a case of 30-year-old female with unilateral proptosis. On the basis of computed tomography (CT) scan and magnetic resonance imaging (MRI), a provisional diagnosis of polyostotic FD was made. Patient was treated surgically. Histopathological reports confirmed the diagnosis.
| Case Report|| |
A 30-year-old female patient presented with protrusion of the right eye and lacrimation since 3 months. On examination, there was a diffuse, nontender, hard, bony swelling over right maxillary and zygomatic area [Figure 1] also covering parietal, temporal bones [Figure 2] sternum and thoracic vertibra [Figure 3]. On ocular examination, she had axial proptosis of the right eye measuring 3 mm (Hertle's exophthalmometer), with minimal lagophthalmos [Figure 4] and [Figure 5]. Extra ocular movements were full in both eyes. Visual acuity of both eyes was 6/6. There was minimal exposure keratopathy, besides that the anterior and posterior segment were normal in both eyes.
Detailed investigations including hematological tests, CT [Figure 6] and MRI brain and orbit [Figure 7] were done. CT showed ground glass appearance of right parietal, frontal, and temporal bone along with the enlargement of the outer table of skull vault. Dense homogenous pattern of FD along with areas of hypodense attenuation in right temporal bone (squamous and petrous), right sphenoid, clivus, right zygomatico-temporal and right maxillary bone was seen. MRI showed cystic hyperintense area in right fronto-temporo-parieto occipital calvarium causing diffuse thickening and involvement of right sphenoid wings and facial bones viz. right maxilla, zygomatic process. It showed lesion causing mass effect on the right orbit causing displacement of the optic nerve laterally and proptosis of right eyeball.
|Figure 6: CT showing ground glass appearance of right parietal, frontal, and temporal bone and enlargement of the outer table of skull vault.|
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|Figure 7: MRI showing cystic hyperintense area in right fronto-temporoparieto occipital calvarium causing diffuse thickening and involvement of right sphenoid wings and facial bones viz. right maxilla, zygomatic process.|
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Provisional diagnosis of polyostotic FD was made. Patient was then taken up for surgery in consultation with the oro-maxillofacial surgeon and osseous reconturing was done. Infra-orbital sub-ciliary incision [Figure 8]a-c was made and maxilla, zygomatic and sphenoid bones were shaved. Histopathology confirmed the diagnosis. Postoperatively, there was an improvement in proptosis (1 mm by Hertle's exophthalmometer) and lagophthalmos decreased. Patient is following-up since over 1 year [Figure 9]. She has not developed any further complications or recurrence.
|Figure 8: Infra-orbital sub-ciliary incision and shaving of maxilla, zygomatic and sphenoid bones.|
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| Discussion|| |
Fibrous dysplasia is a slow growing, noninherited benign disorder in which fibrous tissue and an immature woven bone replaces the normal cancellous bones. Von Recklinghausen in 1891 first noticed FD.  The term FD was used by Lichtenstein in 1938.  It has no sex predilection and it manifests before the third decade of life, which holds true in our case. GNAS1 gene, which encodes the alpha subunit of stimulatory G protein-coupled receptor and Gs α located at chromosome 20q13.2-13.3 has been recently proposed as etiology for FD. It has been suggested that clinical severity of the lesion depends on the time of appearance of mutation.  Menon et al.,  first reported single bone involvement by the disease process and described it as "monostotic fibrous dysplasia (MFD)". Presently, the terms "monostotic" (single bone) and "polyostotic" (multiple bones) are used to describe the extent of this condition in terms of a number of bones involved. MFD constitutes about 70-80% of FD patients and is mostly seen in the second and third decade. The most commonly involved bones are femur, tibia, ribs, and facial bones. The involvement of facial and cranial bones in FD occurs in nearly 50% of patients with the polyostotic form and in 10-27% of patients with MFD.  The polyostotic form is more frequently seen in female patients, 25% of all patients with polyostotic fibrous dysplasia exhibit the disease in more than half of the skeleton. Jaffe-Lichtenstein syndrome More Details is a variant of polyostotic FD with café-au-lait pigmentation of the skin. Cranio-facial type of FD is confined to face and jaws with two or more bones involvement. FD causes ophthalmic problems such as proptosis, diplopia, ocular motility problem and cosmetic deformity.  CT scan and MRI are the main modalities of investigation for FD. CT images show the characteristics ground glass appearance in sclerotic form and nonhomogenous appearance in cystic and mixed form. It's an effective method to assess the optic nerve compression and cranial nerve entrapment.
Entities that come into the differential diagnosis of FD include nonossifying fibroma, cemento-osseous dysplasia and adamantinoma.  Nonossifying fibroma is typically seen in the lower extremities of children. They are clearly separated from FD by the absence of metaplastic osteoid formation in the fibrous stroma.  Cemento-osseous dysplasia can have a similar radiologic appearance to that of FD. However, biopsy can differentiate the two. Cemento-ossifying dysplasia in histopathology section shows a fibrous connective tissue stroma with numerous areas of hemorrhage. Within this connective tissue background is seen a mixture of woven bone and numerous irregularly shaped cementum like particles. Adamantinoma is usually associated with pain and the lesions keep increasing in size while FD lesions are generally painless and stop growing in size at bone maturity. 
Establishing the diagnosis of FD requires close cooperation between clinician, radiologist and pathologist, which was demonstrated very well in the case reported. Surgery is advocated only in symptomatic cases. Fewer than 1% of the lesions can convert to osteosarcoma, fibrosarcoma, or chondrosarcoma. Medical management with bisphosphonates has been shown to be of benefit in some cases. Irradiation is contraindicated since it may lead to radiation induced sarcoma.  Recent advances in surgical techniques have enabled more radical surgery and immediate reconstruction with good aesthetic and functional outcomes. As per Chen and Noordhoff, there are four surgical groups.  The principles of surgical treatment were based on the zones of involvement:
- Total excision of dysplastic bone of fronto-orbital, zygoma, and upper maxillary origin (zone 1) and primary bone reconstruction;
- Conservative excision on the hair-bearing skull (zone 2), central cranial base (zone 3), and tooth-bearing bones (zone 4);
- Optic canal decompression on patients with orbital dysplasia and decreasing visual acuity.
Osseous reconturing was adopted as a surgical method in our case. As per the surgeon's preference, following the infra-orbital sub-ciliary approach, the zygomatic, sphenoid and facial bones were shaved under general anesthesia. Reduction in proptosis and lagophthalmos was seen postoperatively.
| Conclusion|| |
Thus, a differential diagnosis of FD should be kept in mind when examining a patient of proptosis and a detailed general examination should be done in all patients of orbital proptosis.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9]