|Year : 2018 | Volume
| Issue : 2 | Page : 93-96
Polyostotic fibrous dysplasia without craniofacial involvement: An unusual presentation
Seema Sharma1, Milap Sharma1, Parvinder Singh1, Vipin Sharma2
1 Department of Pediatrics, Dr. Rajendra Prasad Government Medical College, Kangra, Himachal Pradesh, India
2 Department of Orthopaedics, Dr. Rajendra Prasad Government Medical College, Kangra, Himachal Pradesh, India
|Date of Web Publication||10-Dec-2018|
House No. 23, Block-B, Type-V, Dr. Rajendra Prasad Government Medical College, Kangra at Tanda, Himachal Pradesh
Source of Support: None, Conflict of Interest: None
Fibrous dysplasia (FD) is a benign bone disorder resulting into the replacement of bone with fibrous tissue. These fibrous bones are prone for deformities, pain, and pathological fractures, hence requiring treatment. We report a case of polyostotic FD without craniofacial involvement.
Keywords: Dysplasia, polyostotic, precocious
|How to cite this article:|
Sharma S, Sharma M, Singh P, Sharma V. Polyostotic fibrous dysplasia without craniofacial involvement: An unusual presentation. J Sci Soc 2018;45:93-6
|How to cite this URL:|
Sharma S, Sharma M, Singh P, Sharma V. Polyostotic fibrous dysplasia without craniofacial involvement: An unusual presentation. J Sci Soc [serial online] 2018 [cited 2019 May 26];45:93-6. Available from: http://www.jscisociety.com/text.asp?2018/45/2/93/247147
| Introduction|| |
Fibrous dysplasia (FD) is an uncommon, sporadic disorder of the fibro-osseous skeleton characterized by the replacement of bone with fibrous tissue., The lesion was first described by Lichtenstein  in 1938. In 1937, Albright et al. described a syndrome characterized by polyostotic FD that included areas of pigmentation, skeletal changes, and endocrine failure. FD is caused by somatic mutation of the GNAS gene, coding Gs alpha protein, which regulates cAMP. When FD affects only one bone, it is called monostotic FD, and in multiple bone involvement, it is called polyostotic FD., In addition to these forms, there is a hereditary familial form of localized FD, which is called cherubism described by Jones. FD accounts for nearly 5% of the benign bone lesions. The monostotic FD is 8–10 times more common than polyostotic FD. There is no sexual predilection in FD, except for McCune–Albright syndrome (MAS) which affects females exclusively. The polyostotic form usually is seen in children younger than 10 years, whereas monostotic form typically is found in slightly older age group. Widespread involvement of the skeleton is possible along with varying combinations of café au lait skin spots and/or endocrine dysfunction such as precocious puberty, renal phosphate wasting, hyperthyroidism, and/or growth hormone excess. Pain at the involved site is the most common symptom, although more common in adults as compared to children. The diagnosis of FD is possible only by the clinical assessment and typical radiological appearance, i.e., the ground-glass appearance. Confirmation of the diagnosis can be done with biopsy which shows “Chinese letter pattern.” The skeletal sites involved in FD are established most of the times in childhood. Monostotic FD has a different skeletal involvement compared to polyostotic FD. Craniofacial involvement in FD occurs in nearly 100% of polyostotic and 30% of monostotic forms. We report the case of a 7-year-old male child with polyostotic FD without craniofacial involvement.
| Case Report|| |
A 7-year-old male child, second child of nonconsanguineous marriage, presented with pain and swelling of the right lower limb along with difficulty in walking for 2½ months. The pain and swelling in the right lower limb were preceded by fall over the right ankle joint while walking. There was no apparent internal or external bleed. There was no history of weight loss, fever, night sweats, and decreased appetite. On examination, vitals were stable, and general and systemic examination was normal. On local examination, tenderness was present over the proximal and distal parts of the right lower limb. Fundus examination revealed macular choroiditis of the left eye. Keeping in view testicular volume <4 ml and no pubic hair, patient was categorized as Tanner Stage 1. Laboratory investigations showed hemoglobin 11.4 g/dl, total leukocytes count 5400/μl, erythrocyte sedimentation rate 10 mm in 1st h, serum calcium 9 mg/dl, serum phosphorus 4.7 mg/dl, serum alkaline phosphatase (ALP) 261 U/L, serum 25-hydroxyvitamin D 15.95 ng/mL, serum blood urea nitrogen 10 mg/dl, serum creatinine 0.2 mg/dl, and serum prolactin 8.89 ng/mL. Thyroid profile and urine examination were normal. X-rays [Figure 1] and [Figure 2] showed radiolucent lesions in metaphyseal ends of the right femur, right tibia. X-rays of the left side of the appendicular skeleton, skull, and chest were within normal limit. Computed tomography (CT) scan of the right leg [Figure 3] was suggestive of multiple cystic lesions involving the metaphyseal ends of right tibia and femur with well-defined sclerotic margins, endosteal scalloping, but no periosteal reaction, so kept the possibility of polyostotic FD. Injection pamidronate at 1 mg/kg was given over 3 days and repeated every 3 months. Calcium and Vitamin D (1000 mg and 6 lakh U) were also started after giving the injection pamidronate. All these interventions resulted in significant improvement in this child without any adverse effects. In our case, there was no compelling indication to seek a biopsy, any sudden change in the clinical presentation, or behavior of the lesion might warrant further investigation in future.
|Figure 1: X-rays showing radiolucent lesions in metaphyseal ends of the right tibia and distal end of the right femur|
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|Figure 2: X-ray showing radiolucent lesions in metaphyseal end of the proximal right femur|
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|Figure 3: Computed tomography scan of the right lower limb showing multiple cystic lesions involving the metaphyseal ends of right tibia with well-defined sclerotic margins, endosteal scalloping, but no periosteal reaction|
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| Discussion|| |
FD is an uncommon developmental disorder of the bone resulting in conversion of normal bone and marrow into fibrous tissue. Such bones are prone for pathological fractures, pain, deformities, and functional impairment. FD is essentially a disease of young population with incidence of 1:4000–1:10,000. FD is a benign disease resulting from postzygotic activating mutations of the GNAS locus at 20q13.2-q13.3, which codes for the alpha subunit of the Gs G-coupled protein receptor. Gs alpha is central in the cell signal pathway that leads to the generation of the intracellular second messenger, cAMP. cAMP is involved in the signal transduction from multiple cell surface receptors, including parathyroid hormone, follicle-stimulating hormone, luteinizing hormone, thyroid-stimulating hormone, and melanocyte-stimulating hormone. The defect in Gs alpha explains the molecular etiology of the association of extra skeletal manifestations with FD. In bone, this activating mutation results in impaired differentiation and proliferation of bone marrow stromal cells. These cells form the structural framework upon which hematopoiesis occurs in the bone marrow, and a subset of these cells are multipotent cells capable of differentiating into multiple cells, namely osteoblasts, osteocytes, chondrocytes, and bone marrow adipocytes. In FD, these cells are proliferated along with arrest of the normal differentiation resulting into formation of fibro-osseous skeleton. Disease can involve one bone (monostotic) or multiple (polyostotic) and may occur in isolation or in combination with café au lait skin macules and hyperfunctioning endocrinopathies termed as MAS. Bones of the 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., Rarely, FD may be associated with intramuscular myxomas, termed Mazabraud's syndrome. FD is 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 the bone. In most cases, the radiographic and clinical findings are sufficient to diagnose FD without a biopsy. 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 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. Prapayasatok et al. reported a case with a rare radiographic “sunray” appearance in FD. In the presented case, the panoramic radiography revealed a “ground-glass” appearance of the lower long bones on the right side without craniofacial involvement, which is an unusual presentation in polyostotic FD. The differential diagnosis 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. There are three different patterns of polyostotic FD based on the radiographic features, namely pagetoid (56%), sclerotic (23%), and the radiolucent type (21%). Pagetoid and lytic type involves mostly calvarial bones, while skull base and face bones have sclerotic lesions. CT scan is helpful in accurately establishing the diagnosis and the extent of involvement. In doubtful cases, histological examination is done, which shows “Chinese letter” appearance.
If FD is asymptomatic, it can be noticed incidentally in cone beam CT, CT scans, and radiographs. If there is no symptom or evidence of progression during follow-up, surgical treatment is not considered. Surgical intervention is reserved for the prevention and treatment of fractures and major deformities. Studies have reported the nonsurgical treatment of FD with calcitonin, disodium etidronate, and pamidronate. In aggressive forms of FD, increased remodeling activity and bone resorption encouraged the use of calcitonin to inhibit osteoclastic resorption,, while pamidronate which is a potent inhibitor of bone resorption like other biophosphonates has a lasting effect on bone turnover. Pamidronate has been successful in the treatment of Paget's disease, malignant hypercalcemia, lytic bone metastases, multiple myeloma, and osteoporosis. FD treated with intravenous pamidronate showed reduced bone turnover, decreased bone pain, and improvement in radiological lesions. Recurrence of FD is rare when the lesion has occurred in adults, but it is seen more commonly in growth period. Patients with craniofacial FD have the risk of recurrence ranged from 15% to 20%. Concentration of serum ALP may be important marker for the detection of the recurrence of the lesion. The patients who had FD have higher ALP; this may be a reliable marker for estimating tumor progress, and a sudden rise in ALP was correlated with the regrowth of FD by Park et al. Our patient showed promising results with pamidronate therapy without any side effect.
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], [Figure 3]