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Neuroradiology Case of the Week

Case 311

Scott Mooney, MD

Clinical Presentation: Patient is a 68-year-old male with an asymptomatic well-circumscribed lucency in right mandible on dental radiograph.

Imaging Findings: Facial CT - A well-demarcated cavity is present in the right mandibular angle. No cortical disruption is present. The left side of the mandible does not have a similar cavity. After contrast administration, there is enhancing tissue within the cavity consistent with ectopic salivary gland.

Diagnosis: Stafne bone cyst

Discussion: The Stafne cyst was first described by Edward Stafne in 1942. He reported a cavity near the angle of the mandible on radiographs of 34 patients. Classified as a nonodontogenic cyst, it is often an incidental finding on plain radiographs of the mandible. They are asymptomatic, have a predilection for men, with most patients between 20 and 70 years of age. Initially thought to be congenital, the current thought, while disputed, is that they are developmental because of their prepoderence in middle age, and their low incidence in children. It has been referred to with many different names, including static bone cavity, defect of the mandible, lingual mandibular bone cavity, static bone cyst, latent bone cyst, and Stafne bone defect.
     Plain radiography demonstrates a well-defined lucency near the madibular angle between the inferior alveolar canal and the inferior border of the mandible. While the defect can be bilateral, it is usually solitary. CT demonstrates a well-defined cavity in the lingual aspect of the mandibular angle, with sclerotic margins. They can be filled with salivary gland, fat, or other soft tissue.
     If the typical defect is appreciated on plain radiogaphy, usually no further evaluation is needed. There have been reports of salivary gland neoplasm, and some recommend repeat imaging in 3 to 6 months for size monitoring.

References:

1. Stafne EC. Bone cavities situated near the angle of the mandible. J Am Dent Assoc, 1942; 29: 1969-1972.
2. Branstetter BF, Weissman JL, Kaplan SB. Imaging of a Stafne bone cavity: what MR adds and why a new name is needed. AJNR Am J Neuroradiol. 1999 Apr;20(4):587-9. [Medline]
3. Som PM, Curtin HD. Head and Neck Imaging. Mosby. 2003; 944-945.
4. Regezi JA, Sciubba JJ. Oral Pathology. WB Saunders. 1989; 328.
5. Goaz PW, White SC. Oral Radiology. Mosby. 1982; 667-671.