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Radiology Quiz Case 2: Diagnosis

Radiology Quiz Case 2: Diagnosis Diagnosis: Osteochondroma arising from the lateral process of C4 and hereditary multiple exostoses (HME) Hereditary multiple exostoses, familial osteochondromatosis, and diaphyseal aclasis are synonyms for a rare, autosomal dominant clinical condition that is characterized by multiple osteochondromas. An osteochondroma is a cartilage-capped bony excrescence that typically grows from the metaphysis of long bones. It is the most common type of benign bone tumor, with solitary tumors occurring in 1% to 2% of the population. It is also the most common type of radiation-induced benign bone tumor.1Hereditary multiple exostoses were first described by Hunter2in 1835. The overall prevalence is 1:50 000, with virtually all patients presenting in early childhood.3Recent genetic studies have identified mutations in 2 genes— EXT1and EXT2—that are responsible for more than 70% of the cases of HME.4Most of these cases involve loss-of-function mutations supporting a tumor suppressor function of the EXTgenes. EXT1has been shown to regulate chondrocyte proliferation and differentiation during endochondral bone development, thereby providing a promising genetic basis for this disease.5 In HME, the exostoses develop shortly after birth in bones that undergo endochondral ossification, with the knee and humerus being the most common locations. Development of exostoses at the expense of longitudinal growth often results in short stature, which is seen in 40% of cases, as well as leg-length inequality due to asymmetrical growth.1The cartilage cap is histologically identical to the physeal growth plate, and the exostoses increase in size and number with growth but often become latent in adulthood. There is a 1% risk of malignant degeneration into chondrosarcoma or osteosarcoma, although the percentage is slightly higher in patients with HME (3%-5%).1Suspicion of sarcomatous transformation should be raised if any exostosis rapidly increases in size or becomes painful. Osteochondromas can remain asymptomatic; however, they often cause bony and cosmetic deformities. Other complications include fracture through the stalk of a pedunculated exostosis as well as pressure effects on adjacent soft tissues such as neurovascular compromise and bursa formation. Clinically, most cases of HME present either with a painless bony swelling or with a slowly growing mass. On plain radiographic imaging, a well-defined pedunculated or sessile bony excrescence is seen arising from the metaphysis and usually growing away from the joint. Plain radiography alone is usually sufficient to make the diagnosis. Magnetic resonance imaging is the imaging modality of choice in symptomatic cases. It confirms continuity of the parent cortex and marrow with the osteochondroma and the presence of a hyaline cartilage cap, which is very hyperintense on T2- and STIR-weighted images. A cartilage cap thickness exceeding 2 cm in adults should raise the suspicion of malignant transformation.6Magnetic resonance imaging provides excellent demonstration of soft-tissue structures and is used in the diagnosis of reactive bursa formation, impingement syndromes, neurovascular compromise, and postoperative tumor recurrence.6It is the method of choice in diagnosing compression of the spinal cord, nerve roots, and peripheral nerves. Computed tomography is an excellent modality to demonstrate calcified lesions such as osteochondromas. It also effectively shows the continuity of parent bone with the tumor and its associated cartilage cap. Although magnetic resonance imaging is sensitive for fibro-osseous lesion detection, further characterization with plain radiography or computed tomography may provide a more specific diagnosis. Computed tomography, with its multiplanar and 3-dimensional capabilities, is particularly useful in the imaging of pelvic and spinal osteochondromas to determine the bony anatomy and for surgical planning. Ultrasonography can be used to depict the cartilage cap as well as to demonstrate complications such as arterial and venous thrombosis, aneurysm formation, and bursitis. No treatment is necessary for asymptomatic osteochondromas; however, surgical resection should be considered if there is a suggestion of malignant transformation or other significant complications. Surgery is often performed for limb-length discrepancies and forearm deformities. Malignant degeneration usually results in low-grade chondrosarcoma and can be treated with wide excision. In our case of cervical osteochondroma, there were no clinical or radiologic features to suggest malignant transformation, and the patient was treated conservatively with planned surveillance. The solution to a case of “a hard lump to swallow” would have been apparent if the patient's history of HME had been obtained on presentation! Return to Quiz Case 2. Box Section Ref ID Submissions Residents and fellows in otolaryngology are invited to submit quiz cases for this section and to write letters to the Archivescommenting on cases presented. Quiz cases should follow the patterns established. See Instructions for Authors (http://archotol.ama-assn.org/misc/ifora.dtl). Material for CLINICALPROBLEMSOLVING: RADIOLOGYshould be submitted electronically via the online submission and review system at http://manuscripts.archoto.com. Reprints are not available from the authors. References 1. Murphey MDChoi JJKransdorf MJFlemming DJGannon FH Imaging of osteochondroma: variants and complications with radiologic-pathologic correlation. Radiographics 2000;20 (5) 1407- 1434PubMedGoogle ScholarCrossref 2. Hunter J The Works of John Hunter. Vol 1. London, England Longman Rees1835; 3. Schmale GAConrad EU IIIRaskind WH The natural history of hereditary multiple exostoses. J Bone Joint Surg Am 1994;76 (7) 986- 992PubMedGoogle Scholar 4. Wuyts WVan Hul W Molecular basis of multiple exostoses: mutations in the EXT1 and EXT2 genes. Hum Mutat 2000;15 (3) 220- 227PubMedGoogle ScholarCrossref 5. Hilton MJGutiérrez LMartinez DAWells DE EXT1 regulates chondrocyte proliferation and differentiation during endochondral bone development. Bone 2005;36 (3) 379- 386PubMedGoogle ScholarCrossref 6. Woertler KLindner NGosheger GBrinkschmidt CHeindel W Osteochondroma: MR imaging of tumor-related complications. Eur Radiol 2000;10 (5) 832- 840PubMedGoogle ScholarCrossref http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Archives of Otolaryngology - Head & Neck Surgery American Medical Association

Radiology Quiz Case 2: Diagnosis

Archives of Otolaryngology - Head & Neck Surgery , Volume 136 (9) – Sep 20, 2010

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References (6)

Publisher
American Medical Association
Copyright
Copyright © 2010 American Medical Association. All Rights Reserved.
ISSN
0886-4470
eISSN
1538-361X
DOI
10.1001/archoto.2010.141-b
Publisher site
See Article on Publisher Site

Abstract

Diagnosis: Osteochondroma arising from the lateral process of C4 and hereditary multiple exostoses (HME) Hereditary multiple exostoses, familial osteochondromatosis, and diaphyseal aclasis are synonyms for a rare, autosomal dominant clinical condition that is characterized by multiple osteochondromas. An osteochondroma is a cartilage-capped bony excrescence that typically grows from the metaphysis of long bones. It is the most common type of benign bone tumor, with solitary tumors occurring in 1% to 2% of the population. It is also the most common type of radiation-induced benign bone tumor.1Hereditary multiple exostoses were first described by Hunter2in 1835. The overall prevalence is 1:50 000, with virtually all patients presenting in early childhood.3Recent genetic studies have identified mutations in 2 genes— EXT1and EXT2—that are responsible for more than 70% of the cases of HME.4Most of these cases involve loss-of-function mutations supporting a tumor suppressor function of the EXTgenes. EXT1has been shown to regulate chondrocyte proliferation and differentiation during endochondral bone development, thereby providing a promising genetic basis for this disease.5 In HME, the exostoses develop shortly after birth in bones that undergo endochondral ossification, with the knee and humerus being the most common locations. Development of exostoses at the expense of longitudinal growth often results in short stature, which is seen in 40% of cases, as well as leg-length inequality due to asymmetrical growth.1The cartilage cap is histologically identical to the physeal growth plate, and the exostoses increase in size and number with growth but often become latent in adulthood. There is a 1% risk of malignant degeneration into chondrosarcoma or osteosarcoma, although the percentage is slightly higher in patients with HME (3%-5%).1Suspicion of sarcomatous transformation should be raised if any exostosis rapidly increases in size or becomes painful. Osteochondromas can remain asymptomatic; however, they often cause bony and cosmetic deformities. Other complications include fracture through the stalk of a pedunculated exostosis as well as pressure effects on adjacent soft tissues such as neurovascular compromise and bursa formation. Clinically, most cases of HME present either with a painless bony swelling or with a slowly growing mass. On plain radiographic imaging, a well-defined pedunculated or sessile bony excrescence is seen arising from the metaphysis and usually growing away from the joint. Plain radiography alone is usually sufficient to make the diagnosis. Magnetic resonance imaging is the imaging modality of choice in symptomatic cases. It confirms continuity of the parent cortex and marrow with the osteochondroma and the presence of a hyaline cartilage cap, which is very hyperintense on T2- and STIR-weighted images. A cartilage cap thickness exceeding 2 cm in adults should raise the suspicion of malignant transformation.6Magnetic resonance imaging provides excellent demonstration of soft-tissue structures and is used in the diagnosis of reactive bursa formation, impingement syndromes, neurovascular compromise, and postoperative tumor recurrence.6It is the method of choice in diagnosing compression of the spinal cord, nerve roots, and peripheral nerves. Computed tomography is an excellent modality to demonstrate calcified lesions such as osteochondromas. It also effectively shows the continuity of parent bone with the tumor and its associated cartilage cap. Although magnetic resonance imaging is sensitive for fibro-osseous lesion detection, further characterization with plain radiography or computed tomography may provide a more specific diagnosis. Computed tomography, with its multiplanar and 3-dimensional capabilities, is particularly useful in the imaging of pelvic and spinal osteochondromas to determine the bony anatomy and for surgical planning. Ultrasonography can be used to depict the cartilage cap as well as to demonstrate complications such as arterial and venous thrombosis, aneurysm formation, and bursitis. No treatment is necessary for asymptomatic osteochondromas; however, surgical resection should be considered if there is a suggestion of malignant transformation or other significant complications. Surgery is often performed for limb-length discrepancies and forearm deformities. Malignant degeneration usually results in low-grade chondrosarcoma and can be treated with wide excision. In our case of cervical osteochondroma, there were no clinical or radiologic features to suggest malignant transformation, and the patient was treated conservatively with planned surveillance. The solution to a case of “a hard lump to swallow” would have been apparent if the patient's history of HME had been obtained on presentation! Return to Quiz Case 2. Box Section Ref ID Submissions Residents and fellows in otolaryngology are invited to submit quiz cases for this section and to write letters to the Archivescommenting on cases presented. Quiz cases should follow the patterns established. See Instructions for Authors (http://archotol.ama-assn.org/misc/ifora.dtl). Material for CLINICALPROBLEMSOLVING: RADIOLOGYshould be submitted electronically via the online submission and review system at http://manuscripts.archoto.com. Reprints are not available from the authors. References 1. Murphey MDChoi JJKransdorf MJFlemming DJGannon FH Imaging of osteochondroma: variants and complications with radiologic-pathologic correlation. Radiographics 2000;20 (5) 1407- 1434PubMedGoogle ScholarCrossref 2. Hunter J The Works of John Hunter. Vol 1. London, England Longman Rees1835; 3. Schmale GAConrad EU IIIRaskind WH The natural history of hereditary multiple exostoses. J Bone Joint Surg Am 1994;76 (7) 986- 992PubMedGoogle Scholar 4. Wuyts WVan Hul W Molecular basis of multiple exostoses: mutations in the EXT1 and EXT2 genes. Hum Mutat 2000;15 (3) 220- 227PubMedGoogle ScholarCrossref 5. Hilton MJGutiérrez LMartinez DAWells DE EXT1 regulates chondrocyte proliferation and differentiation during endochondral bone development. Bone 2005;36 (3) 379- 386PubMedGoogle ScholarCrossref 6. Woertler KLindner NGosheger GBrinkschmidt CHeindel W Osteochondroma: MR imaging of tumor-related complications. Eur Radiol 2000;10 (5) 832- 840PubMedGoogle ScholarCrossref

Journal

Archives of Otolaryngology - Head & Neck SurgeryAmerican Medical Association

Published: Sep 20, 2010

Keywords: diagnostic radiologic examination,radiology specialty,osteochondroma

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