CLINICAL STUDY
Computed Tomography and Magnetic Resonance Imaging of Maxillofacial Lesions in Renal Osteodystrophy Ahmed Abdel Khalek Abdel Razek, MD Purpose: This study aims to describe the computed tomography (CT) and magnetic resonance (MR) imaging appearance of maxillofacial lesions in renal osteodystrophy. Patients and Methods: We retrospectively reviewed the CT and MR imaging of maxillofacial region in 9 patients (6 females and 3 males with mean age of 31 yr) with renal osteodystrophy. They presented with facial swelling (n = 6), facial disfigurement (n = 2), and oral cavity mass (n = 1). They underwent CT and MR imaging of the maxillofacial region. Results: Brown tumors (n = 6) were seen in the mandible (n = 4) and maxilla (n = 2). They appeared as mixed lytic and sclerotic (n = 4) and sclerotic (n = 2) lesions at CT. The lesions appeared as hypointense at T1-weighted images and of mixed signal intensity at T2-weighted images with intense contrast enhancement (n = 6). Uremic leontiasis ossea (n = 2) appeared at CT as diffuse hyperostosis with protruded maxilla and obliterated sinus. At MR imaging, there was expansion of the maxilla with obliteration of the maxillary sinuses and protrusion of the mandible. The lesion exhibited low signal intensity at T1-weighed images. At T2-weighted images, the lesion showed low signal intensity with small hyperintense lesions. Dystrophic calcification (n = 2) was seen in the parotid and the check. Conclusion: We concluded that CT and MR imaging are helpful for diagnosis and treatment planning of maxillofacial lesions of patients with renal osteodystrophy. Key Words: CT, MR imaging, renal osteodystrophy, leontiasis ossea, brown tumor, soft-tissue calcification Abbreviations: CT, Computed tomography, MR, Magnetic resonance, MDCT, Multidetector computed tomography, TR, Repetition time, TE, Echo time, FOV, Field of view (J Craniofac Surg 2014;25: 1354–1357)
R
enal osteodystrophy refers to a spectrum of bone diseases caused by pathologic alterations in the metabolism of calcium, phosphate, and bone in the context of poorly controlled end-stage renal disease and secondary hyperparathyroidism. Hyperparathyroidism can be classified into primary, which occurs due to
From the Department of Diagnostic Radiology, Mansoura Faculty of Medicine, Mansoura, Egypt. Received December 27, 2013. Accepted for publication January 18, 2014. Address correspondence and reprint requests to Ahmed Abdel Khalek Abdel Razek, MD, Department of Diagnostic Radiology, Mansoura Faculty of Medicine, Mansoura 13351, Egypt; E-mail: [email protected] The author reports no conflict of interest. Copyright © 2014 by Mutaz B. Habal, MD ISSN: 1049-2275 DOI: 10.1097/SCS.0000000000000819
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hyperplasia, benign, or malignant neoplasm of one or more parathyroid glands. Secondary hyperparathyroidism is caused as a result of hypocalcemia, vitamin D deficiency, or secondary to chronic renal insufficiency, which acts as a stimulus for parathyroid hormone production. Tertiary hyperparathyroidism is associated with renal failure and autonomous functioning glands in long-standing secondary hyperparathyroidism cases. The fourth type of hyperparathyroidism has been recognized, which occurs due to increased parathyroid hormone levels synthesized in patients with malignant diseases.1–5 The osseous abnormalities of the maxillofacial region are not uncommon and are among the earliest signs of renal osteodystrophy. However, the disease may be misdiagnosed or undiagnosed in some cases.3–5 There are some studies in the literature describing the computed tomography (CT) and magnetic resonance (MR) imaging appearance of osseous changes of the maxillofacial region in patients with renal osteodystrophy.6–27 The aim of this work was to describe the CT and MR imaging appearance of maxillofacial lesions in renal osteodystrophy.
PATIENTS AND METHODS A retrospective analysis of CT and MR imaging of the maxillofacial region was carried out on 9 patients with renal osteodystrophy. There were 6 females and 3 males, and their age ranged from 18 to 45 years with a mean age 31 years. They presented with facial swelling (n = 6), facial disfigurement (n = 2), and oral mass (n = 1). All patients underwent CT and MR imaging of the maxillofacial region. Biopsy with histopathological examination was done for 5 patients with brown tumors. Informed consent from the patients was waived because the study is retrospective. Approval of ethics committee has been obtained. CT examination of the maxillofacial region was performed using a 16-channel multidetector CT (MDCT) scanner (light speed; GE Healthcare Milwaukee, WI) and 64-MDCT scanner (Brilliance 64; Philips Medical Systems, Cleveland, OH) with a slice collimation of 1 mm reconstructed to 1.25/0.7 mm increment for the 16 MDCT, and a slice collimation of 0.6 mm reconstructed with 0.5 mm increment for the 64 MDCT. The acquisition parameters were 80 kV, 180 mA, pitch of 1, and section thickness of 3 mm. The images are obtained in a soft-tissue– and bone window–level setting. Coronal and sagittal images may be reconstructed from the axial sections. Magnetic resonance imaging examination of the head and neck was performed on a 1.5 T system (Magnetom, Symphony; Siemens, Erlangen, Germany) using head and neck coil. Imaging protocol induced axial/coronal T1-weighted spin echo (TR/TE = 500/15 ms) and T2-weighted fast spin echo (TR/TE = 4000/150 ms). The scanning parameters were slice thickness of 3 mm, interslice gap of 0.5 to 1 mm, matrix of 256 256, and FOV of 25 cm 20 cm. Post-contrast axial, coronal, and sagittal images were done for 5 patients after intravenous injection of gadopentate dimeglumine (Magnevist; Bayer HealthCare Pharmaceuticals, Wayne, NJ) in a dose of 0.1 mmol/kg body weight.
The Journal of Craniofacial Surgery • Volume 25, Number 4, July 2014
Copyright © 2014 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
The Journal of Craniofacial Surgery • Volume 25, Number 4, July 2014
Maxillofacial Lesions in Osteodystrophy
The image analysis was performed by 1 radiologist expert in head and neck imaging since 20 years (A.A.) who was blinded to the clinical presentation of the patient. The images were evaluated for the involved region of the maxillofacial region, signal intensity, enhancement pattern of the lesion, and effect on surrounding structures.
RESULTS Six brown tumors were detected in 5 patients. Two lesions are observed in 1 patient at the maxilla. The lesions were located in the mandible (n = 4) and maxilla (n = 2). On CT, brown tumors appeared as well-defined expansile lesions. The cortex of the lesion was thinned (n = 4) and sclerotic (n = 2). These lesions were complex lytic and sclerotic lesions (n = 4) and sclerotic lesions (n = 2). Brown tumors appeared as low signal intensity on T1-weighted images. At T2-weighted images, the lesions revealed high (n = 4) and mixed signal intensities with hypointense regions (n = 2). All lesions showed avid contrast enhancement (Fig. 1). At CT scan, uremic leontiasis ossea (n = 2) appeared as diffuse marked expansion of the maxillae and mandible. Also, there was loss of buccal cortex of the mandible with preserved lingual surface of the mandible. At MR imaging, there is expansion of the maxilla with obliteration of the maxillary sinuses and protrusion of the mandible. The lesions exhibited low signal intensity on T1-weighted images. At T2-weighted images, the lesions showed mixed signal intensity. Few well-defined small lesions of high signal intensity at T2-weighted images were seen in the mandible and in the right side of the skull vault (Fig. 2). There was encroachment upon the optic nerve in 1 patient. Multiple discrete and confluent regions of dystrophic calcification were detected in 2 patients at the parotid region and right cheek in 1 patient and in the upper eyelid in another patient. The
FIGURE 2. Uremic leontiasis ossea: A, axial CT scan shows diffuse hyperostosis and expansion of the mandible with ill definition of its buccal surface on the right side. B, Sagittal T1-weighted image shows expansion of the maxilla and protrusion of the mandible with low signal intensity. C, Coronal T2-weighted image shows bone expansion with obliteration of maxillary sinuses. D, Axial T2-weighted image shows inhomogeneous mixed signal intensity with few small well-defined hyperintense lesions representing brown tumors.
calcification appeared as multiple discrete dense patchy areas at CT and as signal void regions with no soft-tissue mass at both T1- and T2-weighted images (Fig. 3).
DISCUSSION Renal osteodystrophy appears as late manifestations of severe hyperparathyroidism, as a consequence of undiagnosed or untreated hyperparathyroidism. There are high levels of serum calcium and parathyroid hormone.1–3 Bone changes are primarily due to high bone turnover, often combined with a mineralization defect leading to increased bone deformities. The maxillofacial changes of uremic renal osteodystrophy assume 3 imaging patterns: brown tumors, uremic leontiasis ossea, and dystrophic calcification.2–7 Brown tumor is a focal reactive bone remolding lesion. This tumor represents the terminal stage of bone remodeling processes in hyperparathyroid state. It is usually an uncommon lesion occurring with the frequency of 4.5% in primary hyperparathyroidism and 1.5% to 1.7% in cases of secondary hyperparathyroidism,
FIGURE 1. Brown tumor: A, axial CT scan shows well expansile lytic lesion seen arising from the right alveolar margin. The lesion has thin cortex with few fine septae inside. Another lesion with mixed lytic and sclerotic appearance is seen arising from the posterior aspect of left maxilla. B, Axial T1-weighted image shows intermediate signal intensity of both lesions with fine hypointense regions. C, Axial T2-weighted image of the right-sided lesion shows high signal intensity with hypointense septae and left-sided lesion shows low signal intensity. D, Axial contrast T1-weighted image shows intense contrast enhancement of both lesions with non-enhanced fibrous septae.
FIGURE 3. Dystrophic calcification. A, Coronal CT scan shows multiple discrete and confluent areas of dystrophic calcification seen in the right parotid gland and the right cheek. B, Axial T1-weighted image shows signal void regions of calcification seen within the right parotid gland.
© 2014 Mutaz B. Habal, MD
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The Journal of Craniofacial Surgery • Volume 25, Number 4, July 2014
with overall incidence of 0.1%. Histologically, there is connective tissue stroma containing osteoclastic multinucleated giant cells, hemorrhage, and hemosiderin-laden macrophages. The hemorrhage and hemosiderin give the tumor a brownish color and thus its name. Brown tumor appears as a predominantly solid mass with a partly cystic area. Brown tumors can occur as solitary or multiple lesions.6–10 In the maxillofacial region, brown tumors are most commonly seen in the mandible; maxillary involvement and soft tissue such as palate are rarely reported.10,11 In this study, the brown tumors were located in the mandible in 4 patients and maxilla in only 1 patient. Radiographically, brown tumors are seen as expansile lytic lesions that are usually well defined. The cortex may be thinned or fractured.7,8 The MR imaging findings of brown tumor is variable depending upon the tissue components. The MR imaging findings are nonspecific as hypointensity on T1-weighted images, strong contrast enhancement, and heterogeneous signal intensity on T2-weighted images. The imaging features of a T2-shortening effect by the hemosiderin and fluid-fluid levels have also been described.12–14 A solitary brown tumor may be difficult to differentiate from aneurysmal bone cyst, giant cell tumor, and giant cell reparative granuloma. Multiple cystic or mixed lesions within a single bone are also the expected findings of brown tumors. Correlation with the clinical features and laboratory results are necessary for making the definitive diagnosis.3,12 Brown tumors can compress along adjacent nerves, airway, and pharynx. Brown tumors may regress after parathyroidectomy or medical management. However, surgery is indicated if the lesion is located in a critical anatomical site or it causes a neurological deficit. Brown tumor can respond to correction of the underlying disease. Brown tumors cannot be cured by surgery because they will recur unless the serum calcium and phosphorous are controlled medically and by dialysis until a renal transplant is performed.14,15 In this study, imaging is important for surgical planning of brown tumors as it detects the site of origin, extension, and its relation to surrounding vital structures. Also, the serum calcium and phosphorous are controlled before surgery. Uremic leontiasis ossea is a progressively deforming craniofacial osteodystrophy. Bone biopsy usually shows medullary fibrosis, multiple osteoclastic resorption areas, and osteoblastic hyperactivity responsible for osteoid matrix formation.16,17 Previous studies reported that in patients with uremic leontosis ossea, CT scan shows diffuse hyperostosis and expansion of the maxilla with obliteration of the maxillary sinuses as well as enlargement and sclerosis of the mandible and protruded maxilla. There is serpigenous “tunneling” or channeling within the bone and poor visualization of the cortical bone. MR imaging shows diffuse overgrowth and hypertrophy of the maxilla and mandible with mixed signal intensity of the bone marrow on both T1- and T2-weighted images and protruded maxilla.18–21 Brown tumors may be associated with uremic leontosis ossea. In this study, diffuse bone expansion can be detected at CT scan and MR imaging; however, MR imaging helps for detection of associated brown tumors.22 Uremic leontiasis ossea can be differentiated from craniofacial fibrous dysplasia and Paget disease. Craniofacial fibrous dysplasia appears usually diagnosed at the third decade of life and is typically accompanied by a normal biochemical profile. Fibrous dysplasia leads to expansion, thickening, and then sclerosis in the involved bone. This in turn causes cranial asymmetry and facial deformities in the craniofacial region without other symptoms. Paget disease affects older adults and demonstrates elevated serum alkaline phosphatase. A history of chronic renal disease and dialysis, and a high serum phosphate (and if complicated by tertiary hyperparathyroidism will have a high serum calcium) are very useful in distinguishing renal osteodystrophy from the other diseases. Furthermore,
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the radiographic changes of renal osteodystrophy are diffuse rather than monostotic or multifocal as seen in the aforementioned conditions.18–21 Few studies reported that uremic leontiasis ossea can be complicated by foraminal stenosis in the skull base possibly resulting in upper airway obstruction or cranial nerve compression such as facial palsy or hearing loss. Also, uremic leontiasis ossea may be associated with brown tumors.23–25 In this study, uremic leontosis ossea was associated with encroachment along the optic nerve in 1 patient and with brown tumors in another patient. MR imaging can detect brown tumors within uremic leontiasis ossea. Treatment of chronic kidney disease or total parathyroidectomy may slow or prevent development of leontiasis ossea. However, in some cases, surgery is needed for nerve decompression and for cosmetic purposes. Cross-sectional images with or without 3D reconstruction provides the surgeon with important information before reconstruction or corrective surgery.26 Soft-tissue calcification is a feature of severe renal hyperparathyroidism and is due to chronic elevation of calcium phosphate product, resulting in the precipitation of calcium phosphate. The calcified masses should not be misdiagnosed as tumors and myositis ossificans and surgically excised because they will recur unless the biochemical abnormalities are corrected. High serum calcium and phosphate levels may also cause disseminated calcification in the skin, joints, and arteries.3,27,28 Calcification in renal osteodystrophy has been reported in the eyelid and temporomandibular region.3 Also, calcification of both the internal carotid artery (atherosclerosis) and the external carotid artery (arteriosclerosis) has been reported in some patients. Arterial calcifications typically occur in the medial and intimal elastic tissues, giving a pipestem appearance without prominent luminal involvement.29,30 In this study, dystrophic calcification appears as discrete dense lesions at CT scan and appeared as signal void lesions at T1- and T2-weighted images.
CONCLUSIONS We concluded that cross-sectional imaging with CT and MR imaging is helpful for diagnosis and treatment planning of maxillofacial lesions in patients with renal osteodystrophy.
REFERENCES 1. Fatahzadeh M. The spectrum of orofacial manifestations in renal osteodystrophy: diagnostic challenges of an uncommon presentation. Quintessence Int 2011;42:e78–e88 2. Jevtic V. Imaging of renal osteodystrophy. Eur J Radiol 2003;46:85–95 3. Kahn J, Bourjat P. Imaging of facial changes in hyperparathyroidism. J Radiol 2005;86:999–1002 4. Fraser W. Hyperparathyroidism. Lancet 2009;374:145–158 5. Abdel Razek A. Imaging appearance of bone tumors of the maxillofacial region. World J Radiol 2011;3:125–134 6. Selvi F, Cakarer S, Tanakol R, et al. Brown tumour of the maxilla and mandible: a rare complication of tertiary hyperparathyroidism. Dentomaxillofac Radiol 2009;38:53–58 7. Benhammou A, Meziane M, Dib N, et al. Maxilla-mandibular brown tumors as a first sign of parathyroid adenoma. Ann Otolaryngol Chir Cervicofac 2009;126:216–220 8. Triantafillidou K, Zouloumis L, Karakinaris G, et al. Brown tumors of the jaws associated with primary or secondary hyperparathyroidism. A clinical study and review of the literature. Am J Otolaryngol 2006;27:281–286 9. Soundarya N, Sharada P, Prakash N, et al. Bilateral maxillary brown tumors in a patient with primary hyperparathyroidism: report of a rare entity and review of literature. J Oral Maxillofac Pathol 2011;15:56–59
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Copyright © 2014 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
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10. Ergen F, Ayvaz M, Yildiz A, et al. Brown tumour presenting as a soft-tissue mass. Clin Radiol 2012;67:286–289 11. Sutbeyaz Y, Yoruk O, Bilen H, et al. Primary hyperparathyroidism presenting as a palatal and mandibular brown tumor. J Craniofac Surg 2009;20:2101–2104 12. Hong W, Sung M, Chun K, et al. Emphasis on the MR imaging findings of brown tumor: a report of five cases. Skeletal Radiol 2011;40:205–213 13. Takeshita T, Takeshita K, Abe S, et al. Brown tumor with fluid-fluid levels in a patient with primary hyperparathyroidism: radiological findings. Radiat Med 2006;24:631–634 14. Abdel Razek A, Castillo M. Imaging appearance of primary bony tumors and pseudo-tumors of the spine. J Neuroradiol 2010;37:37–50 15. Mohan M, Neelakandan RS, Siddharth D, et al. An unusual case of brown tumor of hyperparathyroidism associated with ectopic parathyroid adenoma. Eur J Dent 2013;7:500–503 16. Collum J, Jones R, Lynham A, et al. Leontiasis ossea: a presentation of hyperparathyroidism in an indigenous Australian man secondary to chronic renal failure. J Oral Maxillofac Surg 2013;71:56–61 17. Dallaudière B, Lincot J, Cotten A, et al. An unusual facial enlargement. Skeletal Radiol 2013;42:837–838 18. Chang J, Som P, Lawson W. Unique imaging findings in the facial bones of renal osteodystrophy. AJNR Am J Neuroradiol 2007;28:608–609 19. Aggunlu L, Akpek S, Coskun B. Leontiasis ossea in a patient with hyperparathyroidism secondary to chronic renal failure. Pediatr Radiol 2004;34:630–632 20. Asaumi J, Aiga H, Hisatomi M, et al. Advanced imaging in renal osteodystrophy of the oral and maxillofacial region. Dentomaxillofac Radiol 2001;30:59–62
Maxillofacial Lesions in Osteodystrophy
21. DPhil V, Webb M, Martinez S, et al. Uremic leontiasis ossea: “bighead” disease in humans? Radiologic, clinical, and pathologic features. Radiology 1996;199:233–240 22. Taskapan H, Taskapan C, Baysal T, et al.. Maxillary brown tumor and uremic leontiasis ossea in a patient with chronic renal insufficiency. Clin Nephrol 2004;61:360–363 23. Schmidt RH, Rietz LA, Patel BC, et al. Compressive optic neuropathy caused by renal osteodystrophy. Case report. J Neurosurg 2001;95:704–709 24. Abid F, Lalani I, Zakaria A, et al. Cranial nerve palsies in renal osteodystrophy. Pediatr Neurol 2007;36:64–65 25. Shenoy V, Oghalai JS. Chronic pachymeningitis and bilateral facial paralysis secondary to renal osteodystrophy. Arch Otolaryngol Head Neck Surg 2008;134:324–326 26. Rodriguez E, Bluebond-Langner R, Spivak A, et al. Surgical management of maxillofacial uremic osteodystrophy: a case report. J Oral Maxillofac Surg 2007;65:1825–1829 27. Collins WO, Buchman CA. Radiology quiz case 2: metastatic calcifications of the middle and external ear and osteitis fibrosa of the temporal bones as a result of secondary hyperparathyroidism. Arch Otolaryngol Head Neck Surg 2002;128:459–460 28. Abdel Razek A, Huang B. Soft tissue tumors of the head and neck: imaging-based review of the WHO classification. Radiographics 2011;31:1923–1954 29. Suarez-Cunqueiro MM, Duker J, Liebehenschel N, et al. Calcification of the branches of the external carotid artery detected by panoramic radiography: a case report. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2002;94:636–640 30. Macdonald DS, Zhang L, Gu Y. Calcification of the external carotid arteries and their branches. Dentomaxillofac Radiol 2012;41:615–618
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Computed Tomography and Magnetic Resonance Imaging of Maxillofacial Lesions in Renal Osteodystrophy Ahmed Abdel Khalek Abdel Razek, MD Purpose: This study aims to describe the computed tomography (CT) and magnetic resonance (MR) imaging appearance of maxillofacial lesions in renal osteodystrophy. Patients and Methods: We retrospectively reviewed the CT and MR imaging of maxillofacial region in 9 patients (6 females and 3 males with mean age of 31 yr) with renal osteodystrophy. They presented with facial swelling (n = 6), facial disfigurement (n = 2), and oral cavity mass (n = 1). They underwent CT and MR imaging of the maxillofacial region. Results: Brown tumors (n = 6) were seen in the mandible (n = 4) and maxilla (n = 2). They appeared as mixed lytic and sclerotic (n = 4) and sclerotic (n = 2) lesions at CT. The lesions appeared as hypointense at T1-weighted images and of mixed signal intensity at T2-weighted images with intense contrast enhancement (n = 6). Uremic leontiasis ossea (n = 2) appeared at CT as diffuse hyperostosis with protruded maxilla and obliterated sinus. At MR imaging, there was expansion of the maxilla with obliteration of the maxillary sinuses and protrusion of the mandible. The lesion exhibited low signal intensity at T1-weighed images. At T2-weighted images, the lesion showed low signal intensity with small hyperintense lesions. Dystrophic calcification (n = 2) was seen in the parotid and the check. Conclusion: We concluded that CT and MR imaging are helpful for diagnosis and treatment planning of maxillofacial lesions of patients with renal osteodystrophy. Key Words: CT, MR imaging, renal osteodystrophy, leontiasis ossea, brown tumor, soft-tissue calcification Abbreviations: CT, Computed tomography, MR, Magnetic resonance, MDCT, Multidetector computed tomography, TR, Repetition time, TE, Echo time, FOV, Field of view (J Craniofac Surg 2014;25: 1354–1357)
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enal osteodystrophy refers to a spectrum of bone diseases caused by pathologic alterations in the metabolism of calcium, phosphate, and bone in the context of poorly controlled end-stage renal disease and secondary hyperparathyroidism. Hyperparathyroidism can be classified into primary, which occurs due to
From the Department of Diagnostic Radiology, Mansoura Faculty of Medicine, Mansoura, Egypt. Received December 27, 2013. Accepted for publication January 18, 2014. Address correspondence and reprint requests to Ahmed Abdel Khalek Abdel Razek, MD, Department of Diagnostic Radiology, Mansoura Faculty of Medicine, Mansoura 13351, Egypt; E-mail: [email protected] The author reports no conflict of interest. Copyright © 2014 by Mutaz B. Habal, MD ISSN: 1049-2275 DOI: 10.1097/SCS.0000000000000819
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hyperplasia, benign, or malignant neoplasm of one or more parathyroid glands. Secondary hyperparathyroidism is caused as a result of hypocalcemia, vitamin D deficiency, or secondary to chronic renal insufficiency, which acts as a stimulus for parathyroid hormone production. Tertiary hyperparathyroidism is associated with renal failure and autonomous functioning glands in long-standing secondary hyperparathyroidism cases. The fourth type of hyperparathyroidism has been recognized, which occurs due to increased parathyroid hormone levels synthesized in patients with malignant diseases.1–5 The osseous abnormalities of the maxillofacial region are not uncommon and are among the earliest signs of renal osteodystrophy. However, the disease may be misdiagnosed or undiagnosed in some cases.3–5 There are some studies in the literature describing the computed tomography (CT) and magnetic resonance (MR) imaging appearance of osseous changes of the maxillofacial region in patients with renal osteodystrophy.6–27 The aim of this work was to describe the CT and MR imaging appearance of maxillofacial lesions in renal osteodystrophy.
PATIENTS AND METHODS A retrospective analysis of CT and MR imaging of the maxillofacial region was carried out on 9 patients with renal osteodystrophy. There were 6 females and 3 males, and their age ranged from 18 to 45 years with a mean age 31 years. They presented with facial swelling (n = 6), facial disfigurement (n = 2), and oral mass (n = 1). All patients underwent CT and MR imaging of the maxillofacial region. Biopsy with histopathological examination was done for 5 patients with brown tumors. Informed consent from the patients was waived because the study is retrospective. Approval of ethics committee has been obtained. CT examination of the maxillofacial region was performed using a 16-channel multidetector CT (MDCT) scanner (light speed; GE Healthcare Milwaukee, WI) and 64-MDCT scanner (Brilliance 64; Philips Medical Systems, Cleveland, OH) with a slice collimation of 1 mm reconstructed to 1.25/0.7 mm increment for the 16 MDCT, and a slice collimation of 0.6 mm reconstructed with 0.5 mm increment for the 64 MDCT. The acquisition parameters were 80 kV, 180 mA, pitch of 1, and section thickness of 3 mm. The images are obtained in a soft-tissue– and bone window–level setting. Coronal and sagittal images may be reconstructed from the axial sections. Magnetic resonance imaging examination of the head and neck was performed on a 1.5 T system (Magnetom, Symphony; Siemens, Erlangen, Germany) using head and neck coil. Imaging protocol induced axial/coronal T1-weighted spin echo (TR/TE = 500/15 ms) and T2-weighted fast spin echo (TR/TE = 4000/150 ms). The scanning parameters were slice thickness of 3 mm, interslice gap of 0.5 to 1 mm, matrix of 256 256, and FOV of 25 cm 20 cm. Post-contrast axial, coronal, and sagittal images were done for 5 patients after intravenous injection of gadopentate dimeglumine (Magnevist; Bayer HealthCare Pharmaceuticals, Wayne, NJ) in a dose of 0.1 mmol/kg body weight.
The Journal of Craniofacial Surgery • Volume 25, Number 4, July 2014
Copyright © 2014 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
The Journal of Craniofacial Surgery • Volume 25, Number 4, July 2014
Maxillofacial Lesions in Osteodystrophy
The image analysis was performed by 1 radiologist expert in head and neck imaging since 20 years (A.A.) who was blinded to the clinical presentation of the patient. The images were evaluated for the involved region of the maxillofacial region, signal intensity, enhancement pattern of the lesion, and effect on surrounding structures.
RESULTS Six brown tumors were detected in 5 patients. Two lesions are observed in 1 patient at the maxilla. The lesions were located in the mandible (n = 4) and maxilla (n = 2). On CT, brown tumors appeared as well-defined expansile lesions. The cortex of the lesion was thinned (n = 4) and sclerotic (n = 2). These lesions were complex lytic and sclerotic lesions (n = 4) and sclerotic lesions (n = 2). Brown tumors appeared as low signal intensity on T1-weighted images. At T2-weighted images, the lesions revealed high (n = 4) and mixed signal intensities with hypointense regions (n = 2). All lesions showed avid contrast enhancement (Fig. 1). At CT scan, uremic leontiasis ossea (n = 2) appeared as diffuse marked expansion of the maxillae and mandible. Also, there was loss of buccal cortex of the mandible with preserved lingual surface of the mandible. At MR imaging, there is expansion of the maxilla with obliteration of the maxillary sinuses and protrusion of the mandible. The lesions exhibited low signal intensity on T1-weighted images. At T2-weighted images, the lesions showed mixed signal intensity. Few well-defined small lesions of high signal intensity at T2-weighted images were seen in the mandible and in the right side of the skull vault (Fig. 2). There was encroachment upon the optic nerve in 1 patient. Multiple discrete and confluent regions of dystrophic calcification were detected in 2 patients at the parotid region and right cheek in 1 patient and in the upper eyelid in another patient. The
FIGURE 2. Uremic leontiasis ossea: A, axial CT scan shows diffuse hyperostosis and expansion of the mandible with ill definition of its buccal surface on the right side. B, Sagittal T1-weighted image shows expansion of the maxilla and protrusion of the mandible with low signal intensity. C, Coronal T2-weighted image shows bone expansion with obliteration of maxillary sinuses. D, Axial T2-weighted image shows inhomogeneous mixed signal intensity with few small well-defined hyperintense lesions representing brown tumors.
calcification appeared as multiple discrete dense patchy areas at CT and as signal void regions with no soft-tissue mass at both T1- and T2-weighted images (Fig. 3).
DISCUSSION Renal osteodystrophy appears as late manifestations of severe hyperparathyroidism, as a consequence of undiagnosed or untreated hyperparathyroidism. There are high levels of serum calcium and parathyroid hormone.1–3 Bone changes are primarily due to high bone turnover, often combined with a mineralization defect leading to increased bone deformities. The maxillofacial changes of uremic renal osteodystrophy assume 3 imaging patterns: brown tumors, uremic leontiasis ossea, and dystrophic calcification.2–7 Brown tumor is a focal reactive bone remolding lesion. This tumor represents the terminal stage of bone remodeling processes in hyperparathyroid state. It is usually an uncommon lesion occurring with the frequency of 4.5% in primary hyperparathyroidism and 1.5% to 1.7% in cases of secondary hyperparathyroidism,
FIGURE 1. Brown tumor: A, axial CT scan shows well expansile lytic lesion seen arising from the right alveolar margin. The lesion has thin cortex with few fine septae inside. Another lesion with mixed lytic and sclerotic appearance is seen arising from the posterior aspect of left maxilla. B, Axial T1-weighted image shows intermediate signal intensity of both lesions with fine hypointense regions. C, Axial T2-weighted image of the right-sided lesion shows high signal intensity with hypointense septae and left-sided lesion shows low signal intensity. D, Axial contrast T1-weighted image shows intense contrast enhancement of both lesions with non-enhanced fibrous septae.
FIGURE 3. Dystrophic calcification. A, Coronal CT scan shows multiple discrete and confluent areas of dystrophic calcification seen in the right parotid gland and the right cheek. B, Axial T1-weighted image shows signal void regions of calcification seen within the right parotid gland.
© 2014 Mutaz B. Habal, MD
Copyright © 2014 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
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The Journal of Craniofacial Surgery • Volume 25, Number 4, July 2014
with overall incidence of 0.1%. Histologically, there is connective tissue stroma containing osteoclastic multinucleated giant cells, hemorrhage, and hemosiderin-laden macrophages. The hemorrhage and hemosiderin give the tumor a brownish color and thus its name. Brown tumor appears as a predominantly solid mass with a partly cystic area. Brown tumors can occur as solitary or multiple lesions.6–10 In the maxillofacial region, brown tumors are most commonly seen in the mandible; maxillary involvement and soft tissue such as palate are rarely reported.10,11 In this study, the brown tumors were located in the mandible in 4 patients and maxilla in only 1 patient. Radiographically, brown tumors are seen as expansile lytic lesions that are usually well defined. The cortex may be thinned or fractured.7,8 The MR imaging findings of brown tumor is variable depending upon the tissue components. The MR imaging findings are nonspecific as hypointensity on T1-weighted images, strong contrast enhancement, and heterogeneous signal intensity on T2-weighted images. The imaging features of a T2-shortening effect by the hemosiderin and fluid-fluid levels have also been described.12–14 A solitary brown tumor may be difficult to differentiate from aneurysmal bone cyst, giant cell tumor, and giant cell reparative granuloma. Multiple cystic or mixed lesions within a single bone are also the expected findings of brown tumors. Correlation with the clinical features and laboratory results are necessary for making the definitive diagnosis.3,12 Brown tumors can compress along adjacent nerves, airway, and pharynx. Brown tumors may regress after parathyroidectomy or medical management. However, surgery is indicated if the lesion is located in a critical anatomical site or it causes a neurological deficit. Brown tumor can respond to correction of the underlying disease. Brown tumors cannot be cured by surgery because they will recur unless the serum calcium and phosphorous are controlled medically and by dialysis until a renal transplant is performed.14,15 In this study, imaging is important for surgical planning of brown tumors as it detects the site of origin, extension, and its relation to surrounding vital structures. Also, the serum calcium and phosphorous are controlled before surgery. Uremic leontiasis ossea is a progressively deforming craniofacial osteodystrophy. Bone biopsy usually shows medullary fibrosis, multiple osteoclastic resorption areas, and osteoblastic hyperactivity responsible for osteoid matrix formation.16,17 Previous studies reported that in patients with uremic leontosis ossea, CT scan shows diffuse hyperostosis and expansion of the maxilla with obliteration of the maxillary sinuses as well as enlargement and sclerosis of the mandible and protruded maxilla. There is serpigenous “tunneling” or channeling within the bone and poor visualization of the cortical bone. MR imaging shows diffuse overgrowth and hypertrophy of the maxilla and mandible with mixed signal intensity of the bone marrow on both T1- and T2-weighted images and protruded maxilla.18–21 Brown tumors may be associated with uremic leontosis ossea. In this study, diffuse bone expansion can be detected at CT scan and MR imaging; however, MR imaging helps for detection of associated brown tumors.22 Uremic leontiasis ossea can be differentiated from craniofacial fibrous dysplasia and Paget disease. Craniofacial fibrous dysplasia appears usually diagnosed at the third decade of life and is typically accompanied by a normal biochemical profile. Fibrous dysplasia leads to expansion, thickening, and then sclerosis in the involved bone. This in turn causes cranial asymmetry and facial deformities in the craniofacial region without other symptoms. Paget disease affects older adults and demonstrates elevated serum alkaline phosphatase. A history of chronic renal disease and dialysis, and a high serum phosphate (and if complicated by tertiary hyperparathyroidism will have a high serum calcium) are very useful in distinguishing renal osteodystrophy from the other diseases. Furthermore,
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the radiographic changes of renal osteodystrophy are diffuse rather than monostotic or multifocal as seen in the aforementioned conditions.18–21 Few studies reported that uremic leontiasis ossea can be complicated by foraminal stenosis in the skull base possibly resulting in upper airway obstruction or cranial nerve compression such as facial palsy or hearing loss. Also, uremic leontiasis ossea may be associated with brown tumors.23–25 In this study, uremic leontosis ossea was associated with encroachment along the optic nerve in 1 patient and with brown tumors in another patient. MR imaging can detect brown tumors within uremic leontiasis ossea. Treatment of chronic kidney disease or total parathyroidectomy may slow or prevent development of leontiasis ossea. However, in some cases, surgery is needed for nerve decompression and for cosmetic purposes. Cross-sectional images with or without 3D reconstruction provides the surgeon with important information before reconstruction or corrective surgery.26 Soft-tissue calcification is a feature of severe renal hyperparathyroidism and is due to chronic elevation of calcium phosphate product, resulting in the precipitation of calcium phosphate. The calcified masses should not be misdiagnosed as tumors and myositis ossificans and surgically excised because they will recur unless the biochemical abnormalities are corrected. High serum calcium and phosphate levels may also cause disseminated calcification in the skin, joints, and arteries.3,27,28 Calcification in renal osteodystrophy has been reported in the eyelid and temporomandibular region.3 Also, calcification of both the internal carotid artery (atherosclerosis) and the external carotid artery (arteriosclerosis) has been reported in some patients. Arterial calcifications typically occur in the medial and intimal elastic tissues, giving a pipestem appearance without prominent luminal involvement.29,30 In this study, dystrophic calcification appears as discrete dense lesions at CT scan and appeared as signal void lesions at T1- and T2-weighted images.
CONCLUSIONS We concluded that cross-sectional imaging with CT and MR imaging is helpful for diagnosis and treatment planning of maxillofacial lesions in patients with renal osteodystrophy.
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Copyright © 2014 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
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Copyright © 2014 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.
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