Tumores

Value of computed tomography findings in differentiating between intraosseous malignant tumors and osteomyelitis of the mandible affecting the masticator space
Yasushi Hariya, DDS,a Kenji Yuasa, DDS, PhD,b Eiji Nakayama, DDS, PhD,c Toshiyuki Kawazu, DDS,d Kazutoshi Okamura, DDS, PhD,d and Shigenobu Kanda, DDS, PhD,e Sapporo and Fukuoka Japan
SAPPORO MEDICAL UNIVERSITY, FUKUOKA DENTAL COLLEGE,AND KYUSHU UNIVERSITY

Objectives. We sought to evaluate the diagnostic efficacy of computed tomography (CT) images in the differentiation between intraosseous malignant tumors and osteomyelitis spreading into the masticator space. Study design. A retrospective evaluation was carried out by using CT images from 12 patients with intraosseous malignant tumors and 9 patients with osteomyelitisinvolving the masticator space and accompanying mandibular bone destruction. The following CT observations are discussed: (1) bone destruction pattern subdivided into spotty, gross, or permeative; (2) cortical bone expansion; (3) diffuse osteosclerotic changes; (4) periosteal reaction; (5) masticator muscle involvement; (6) enlargement of the facial muscle; and (7) attenuation in the subcutaneous adiposetissue. Results. The pattern of permeative bone destruction, cortical bone expansion, and the enlargement of both the masseter and medial pterygoid muscles were all observed in patients with malignant tumors. In contrast, diffuse sclerotic change and a periosteal reaction were significant observations in patients with osteomyelitis. Conclusion. The efficacy of CT in establishing a differentialdiagnosis of malignant tumors or osteomyelitis is supported by this study. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2003;95:503-9)

Both odontogenic infections and malignant tumors of the oral cavity may spread into the masticator space (MS), resulting in enlargement of the masticator muscles.1,2 The MS is a distinct deep facial region that is bounded by superficial layers of the deepcervical fascia. It consists of the ramus and posterior body of the mandible and the masseter, the medial pterygoid, the lateral pterygoid, and the temporalis muscles. The fascia provides a barrier against the spread of infection and tumors.3 The border of the MS adjoins the buccal space anteriorly, the parotid space posteriorly, the sublingual and submandibular spaces inferiorly, and the parapharyngealspace medially.4 The mandible is the central
a

Resident, Department of Oral Surgery, Sapporo Medical University School of Medicine, Sapporo, Japan. b Professor, Department of Diagnostics and General Care, Fukuoka Dental College, Fukuoka, Japan. c Assistant Professor, Department of Oral and Maxillofacial Radiology, Faculty of Dental Science, Kyushu University, Fukuoka, Japan. d Instructor,Department of Oral and Maxillofacial Radiology, Faculty of Dental Science, Kyushu University, Fukuoka, Japan. e Professor and Chairman, Department of Oral and Maxillofacial Radiology, Faculty of Dental Science, Kyushu University, Fukuoka, Japan. Received for publication Aug 3, 2000; returned for revision Sep 17, 2000; accepted for publication Oct 2, 2002. © 2003, Mosby, Inc. All rights reserved.1079-2104/2003/$30.00 0 doi:10.1067/moe.2003.134

structure of the MS, which is divided into medial and lateral compartments. Computed tomography (CT) easily reveals the anatomy of the MS and the extension of the lesion.1,2 However, primary intraosseous malignant tumors of the mandible resemble inflammation associated with mandibular bone destruction in both the clinical symptoms and radiographicfindings.5,6 Therefore, it may be difficult to differentiate between intraosseous malignant tumors and osteomyelitis with bone destruction of the mandible spreading into the MS as demonstrated clinically and on CT images. Ida et al7 reported that the pattern of periosteal reaction on the computed tomographs in combination with the pattern of cortical destruction are an indicator of the invasiveness...