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Neuroradiology Case of
the Week
Case 260
Brady Huang, MD, and P-L Westesson, MD, PhD, DDS
Clinical
Presentation: Patient is a
34 year-old male status post motor vehicle collision. There is concern for injury to the maxillofacial skeleton.
Imaging Findings:
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Figure 1: Coronal CT image through the maxillary sinus shows a round soft tissue attenuation lesion in the floor of the right maxillary sinus with a thin peripheral rim of calcification. There roots of the first maxillary molar project into this lesion, and the alveolar ridge appears to "lifted" and continuous with the rim of calcification.
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| Figure 2.
Oblique sagittal reformatted CT image of through the right maxillary sinus again show the roots of the first maxillary molar projecting into a peripherally calcified soft tissue lesion. |
Diagnosis: Radicular (periapical) cyst.
Differential Diagnosis: Follicular (dentigerous) cyst, keratocystic odontogenic tumor
Discussion: The adult maxillary sinus is an air-filled cavity within the body of the maxilla. It is the first paranasal sinus to develop during approximately the third month of fetal life, and can continue to pneumatize even after the eruption of the permanent teeth. Pneumatization can continue to occur such that only sinus mucoperiosteum is left (Schneiderian membrane). In the adult, the third molar roots are closest to the floor of the maxillary sinus followed by first and third molars, the second and first premolars, and canines.
Maxillary sinus lesions of the sinus floor can arise primarily from the antra or from the dental structures. Cysts are classified as intrinsic if derived from the antra, and extrinsic when they arise from an odontogenic source. Cysts arising from the sinus mucosa include pseudocysts, mucoceles, and most commonly, retention cysts. Intrinsic cysts should not be considered if they have a cortical lining. Extrinsic cysts include dentigerous cysts, calcifying odontogenic cysts, odontogenic keratocysts, and radicular cysts (periodontal).
This case demonstrates a radicular or periapical cyst, the most common type of jaw cyst. These are often found incidentally on dental radiography. They arise from epithelial residues in periodontal ligament secondary to inflammation. They can become secondarily infected. These are seen in both the maxilla and mandible, particularly the anterior portion of the maxilla. Males are more affected than females and are usually found in the 3rd and 4th decades. These lesions are radiolucent and expansible and have a thin sclerotic border. If the offending tooth is removed and the cyst remains, this is termed a residual cyst.
References:
- Larheim, T.A., Westesson, P-L. Maxillofacial Imaging. Springer 2005.
- Mehra P. Murad H. Maxillary sinus disease of odontogenic origin. Otolaryngol Clin North Am. 2004 Apr;37(2):347-64. [Medline]
- Ericson, S. Conventional and computerized imaging of maxillary sinus pathology related to dental problems. Oral Maxillofacial Surg Clin N Am. 1992;4(1):153-81.
- Maloney PL. Doku HC. Maxillary sinusitis of odontogenic origin. J Can Dent Assoc (Tor). 1968 Nov;34(11):591-603. [Medline]
- Legert KG. Zimmerman M. Stierna P. Sinusitis of odontogenic origin: pathophysiological implications of early treatment. Acta Otolaryngol. 2004 Aug;124(6):655-63. [Medline]
- Falk H, Ericson S, Hugoson A. The effects of periodontal treatment on mucous membrane thickening in the maxillary sinus. J Clin Periodontol. 1986 Mar;13(3):217-22. [Medline]
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