Abstract
Diagnosis: Classic osteosarcoma of the temporal bone On microscopy, a tumor composed of osteoid-producing atypical osteoblasts was evident just beneath the skin, and the diagnosis of osteosarcoma was established. A thallium 201 scan did not reveal another hot spot. Treatment consisted of chemotherapy, followed by a radical mastoidectomy. The osteosarcoma is best defined as a malignant tumor of mesenchymal cells characterized by the direct formation of osteoid or bone by the tumor cells. Some osteosarcomas are composed largely of fibroblastic cells, and others have abundant bone formation. Some show chondroid differentiation, and others are highly vascular (telangiectatic), but they all have tumor-produced osteoid formation marked by trapping of anaplastic tumor cells within the lacunae of the osteoid matrix.1,2 Most conventional osteosarcomas arise in the medullary cavity of the metaphyseal end of the long bones of the extremities. Approximately 60% to 70% of all tumors arise close to the knee. However, any bone may be involved, and in persons older than 25 years, the incidence in flat bones (eg, jaws or pelvis) and long bones is almost equal.2,3 Osteosarcomas of the craniofacial bones are relatively rare, representing fewer than 10% of all osteosarcomas. The male-female ratio is close to 1:1. The most commonly affected bones of the head and neck are the mandible, followed by the maxilla. Osteosarcomas of other skull bones are extremely rare. To our knowledge, 12 cases of osteosarcoma originating in temporal bone have been reported in the English-language literature.4,5 The radiographic appearance of osteosarcomas in the head and neck is characteristic of bone-producing osteosarcomas in general. Because of its location, osteosarcoma of the head and neck tends to be diagnosed earlier, and the tumor can remain localized for a longer period than the classic fully malignant osteosarcoma of adolescents. Its location also precludes very radical surgery, and there is a high incidence of local recurrence after primary surgery. Osteosarcomas of the skull, other than those of the mandible and maxilla, seem to carry an even worse prognosis owing to the difficulty of radical resection of the tumor. Multiple local recurrences often occur before distant metastases develop.6,7 Radiologically, osteosarcoma may be identified as the probable diagnosis because of such classic findings as osseous destruction, a wide transition zone, mineralization of the tumor matrix, and a soft tissue component. However, because of the rare location of the tumor in the temporal bone, differential diagnosis should be made on the basis of the other lesions that are encountered more frequently within this bone and that have some imaging features in common.6-8 The tumors of mastoid component of the temporal bone may be primary lesions, distant metastases, or invasive from neighboring tissues such as the parotid gland.3 The lesions that originate in the temporal bone are Langerhans cell histiocytosis, osteoblastomas, solitary plasmacytomas, osteomas, epidermoids, hemangiomas, cholesterol granulomas, chondromas, and metastases.1,8 In conclusion, when computed tomographic features like those described herein are encountered, the diagnosis of osteosarcoma should be considered, even though the temporal bone is an unusual location for this type of tumor. References 1. Iain WCobby M Tumors and tumorlike conditions of bone. In: Sutton D, ed. Textbook of Radiology and Imaging.6th ed. New York, NY: Churchill Livingstone Inc; 1998:142-150Google Scholar 2. Hasso ANVignaud JRoger CB Pathology of the temporal bone and mastoid. In: Newton TH, Hasso AN, Dillon WP, eds. Computed Tomography of the Head and Neck. New York, NY: Raven Press; 1988:5.1-5.45Google Scholar 3. Harnsberger RH Handbook of Head and Neck Imaging. 2nd ed. St Louis, Mo: Mosby–Year Book Inc; 1995 4. Alleyne CH JrTheodore NSpetzler RFCoons SW Osteosarcoma of the temporal fossa with hemorrhagic presentation: case report. Neurosurgery 2000;47447- 450PubMedGoogle ScholarCrossref 5. Sharma SCHanda KKPanda N et al. Osteogenic sarcoma of the temporal bone. Am J Otolaryngol 1997;18220- 223PubMedGoogle ScholarCrossref 6. Lee YYVan Tassel PNauert CRaymond AKEdeiken J Craniofacial osteosarcomas: plain film, CT, and MR findings in 46 cases. AJR Am J Roentgenol 1988;1501397- 1402PubMedGoogle ScholarCrossref 7. Imhof HHenk CBDirisamer ACzerny CGstottner W CT and MRI characteristics of tumours of the temporal bone and the cerebello-pontine angle [in German]. Radiologe 2003;43219- 226PubMedGoogle ScholarCrossref 8. Spina VMontanari NRomagnoli R Malignant tumors of the osteogenic matrix. Eur J Radiol 1998;27(suppl 1)S98- S109PubMedGoogle ScholarCrossref
Journal
Archives of Otolaryngology - Head & Neck Surgery
– American Medical Association
Published: Oct 1, 2005
Keywords: radiology specialty,osteosarcoma,temporal bone,neoplasms
