Volume 40 • Number 6 March 15, 2017 Mandibular Lesions: A Practical Approach for Diagnosis Based on Multimodality Imaging Findings Rami Eldaya, MD, MBA, Omar Eissa, MD, Stephen Herrmann, MD, Jax Pham, DO, Susana Calle, MD, and Tomas Uribe, MD After participating in this educational activity, the diagnostic radiologist should be better able to diagnose many different benign and malignant lesions involving the mandible. Category: General Radiology forming the temporomandibular joint. The outer cortical Subcategory: Musculoskeletal bone of the mandible is known as the buccal surface, and the Modality: CT inner cortex is known as the lingual surface. Between the two cortices, there is trabecular bone and the alveolar canal, which carries the mandibular nerves. Key Words: Mandible, Mandibular Cystic Lesions, The mandible is a common site for more than 30 different Mandibular Odontogenic Solid Tumors, Tooth-Related lesions.1 Multiple lesion classifi cations have been proposed, Sclerotic Mandibular Lesions, Nonodontogenic Mandibular including classifi cations based on origin (odontogenic vs. Tumors nonodontogenic); location; appearance (cystic vs. solid); The mandible is a physiologically complex bone that plays or pathology. Understanding all of the mentioned classifi ca- a role in phonation, mastication, and jaw stability. It is a tions is by far the best approach to appreciate the complex strong fl at bone that serves as an anchor for the lower denti- overlapping pathologies. tion and an attachment site for masticator muscles and facial muscles. The mandible is composed of multiple bony seg- Given the diversity and extensive pathologies affecting the ments including a U-shaped body segment that fuses in the mandible, it is diffi cult to assess every lesion in great details anterior midline at the symphysis menti and extends poste- within a single review. This article serves as a selective riorly to the vertical ramus segments. Each ramus connects review, emphasizing the most common lesions, lesions with a to the body through the angle. The ramus extends cranially classical “Aunt Minnie” imaging appearance, and important to form the coronoid process and mandibular condyle, which “cannot miss lesions.” are separated by the mandibular notch. The mandibular con- dyle articulates with the temporal bone at the glenoid fossa Mandibular Cystic Lesions Keratocystic Odontogenic Tumor Dr. Eldaya, Dr. Eissa, Dr. Herrmann, and Dr. Pham are Residents, Department Keratocystic odontogenic tumors are common lesions, of Radiology, University of Texas Medical Branch, Galveston, Texas; Dr. Calle constituting 5% to 15% of all jaw cysts.2 They mostly present is a Fellow, Department of Diagnostic and Interventional Imaging, University in young adults in the second to fourth decades of life and of Texas MD Anderson Cancer Center, Houston, Texas; and Dr. Uribe is Assistant Professor of Neuroradiology, Department of Radiology, Baylor College are thought to arise from the dental lamina (band of ectoder- of Medicine, One Baylor Plaza, MS360, Houston, TX 77030; E-mail: tacosta@ mal cells giving rise to the teeth and enamel). Keratocystic bcm.edu. odontogenic tumors can expand and thin the cortex. They The authors and all staff in a position to control the content of this CME activity typically have associated daughter cysts, which explain their and their spouses/life partners (if any) have disclosed that they have no relation- ships with, or fi nancial interests in, any commercial organizations pertaining to high recurrence rate (50%) when treated with curettage. On this educational activity. imaging, these lesions are unilocular, lucent, expansile, and Lippincott Continuing Medical Education Institute, Inc., is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians. Lippincott Continuing Medical Education Institute, Inc., designates this enduring material for a maximum of 2 AMA PRA Category 1 Credits™. Physicians should only claim credit commensurate with the extent of their participation in the activity. To earn CME credit, you must read the CME article and complete the quiz and evaluation on the enclosed answer form, answering at least seven of the 10 quiz questions correctly. This continuing medical education activity expires on March 14, 2018. 1 CCDRv40n6.inddDRv40n6.indd 1 002/02/172/02/17 55:06:06 PPMM Figure 1. Keratocystic odontogenic tumor. Axial, nonenhanced CT scan demonstrates a unilocular, expansile, lucent lesion (blue arrow) within the body of the mandible resulting in thinning and erosion of the overlying cortex (green arrow) associated with an unerupted tooth (circle). Location, expansile appearance, and unerupted tooth combination strongly suggest the diagnosis of keratocystic odontogenic tumor. Figure 2. Traumatic (simple) bone cyst. Sagittal, nonenhanced CT scan demonstrates a unilocular, lucent, nonexpansile lesion that is corticated but with scalloping of the inferomedial margin often with thin overlying cortex, potentially eroding it (arrow) incidentally noted in a 24-year-old man. The imaging (Figure 1). Keratocystic odontogenic tumors can be associ- appearance and clinical picture suggest the diagnosis of a trau- ated with unerupted teeth and most commonly occur in the matic bone cyst. body and ramus of the mandible.1 The treatment is usually surgical removal with wide margins to remove potential daughter cells. The presence of multiple keratocystic odon- true cysts as they do not contain a true epithelial lining. The togenic tumors should raise concern for Gorlin-Goltz syn- pathophysiology of these lesions is not clearly understood drome (i.e., basal cell nevi, multiple keratocystic odontogenic but is thought to be secondary to traumatic hemorrhage with tumors, and skeletal malformations). subsequent bone resorption.3 Traumatic bone cysts typically occur in the second decade of life and usually are detected Keratocystic odontogenic tumors typically have incidentally. They typically appear on imaging as unilocular, associated daughter cysts, which also must lucent lesions with scalloped, thinned cortical margins be removed when treated with curettage to extending between the teeth roots (Figure 2). prevent recurrence. Dentigerous (Follicular) Cyst Dentigerous cysts are the most common developmental/ noninflammatory odontogenic cysts.2 Dentigerous cysts Traumatic (Simple) Bone Cyst occur mostly in young adults, with peak incidence between The mandible is the most common location for traumatic the second and fourth decades of life. Dentigerous cysts occur bone cysts.1 Although these are labeled as cysts, they are not secondary to proliferation of the lining of the dental follicle. The continuing education activity in Contemporary Diagnostic Radiology is intended for radiologists. EDITOR: Robert E. Campbell, MD, Clinical Professor of Radiology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania Contemporary Diagnostic Radiology (ISSN 0149-9009) is published bi-weekly by Lippincott Williams & Wilkins, Inc., 14700 Citicorp Drive, Bldg 3, Hagerstown, MD 21742. Customer Service: Phone (800) 638-3030; Fax (301) 223-2400; E-mail: [email protected]. Visit our website at LWW.com. 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For quantities of 500 or under, e-mail [email protected], call 866-903-6951, or fax 410-528-4434. 2 CCDRv40n6.inddDRv40n6.indd 2 002/02/172/02/17 55:06:06 PPMM Figure 4. Ameloblastoma. Axial, contrast enhanced CT scan Figure 3. Dentigerous cyst. Axial, nonenhanced CT scan dem- demonstrates a well-defi ned, expansile, lucent lesion completely onstrates a corticated, lucent mandibular lesion containing the eroding multiple teeth,