Odontogenic myxoma of the maxilla.

Odontogenic myxomas are rare benign tumors that can exert destructive effects in some cases. They typically affect patients between the ages of 20 and 40 years, although some pediatric cases have been reported. (1,2) Odontogenic myxomas account for up to 12% of all odontogenic tumors.

We evaluated a 33-year-old woman who had undergone extraction of the upper right premolar and subsequently experienced pain and purulent material drainage at the site of the extraction. She also exhibited a mild facial deformity secondary to what appeared to be an expansile mass at the site of the extraction. Dental x-rays identified a cyst-like formation between the upper right premolar and the upper right incisor. Computed tomography (CT) revealed that an isodense, expansile mass had expanded and deformed the base of the right maxillary sinus (figure 1). As a result, the walls of the sinus were thinned and the teeth were spread. A magnetic resonance imaging (MRI) examination with a paramagnetic contrast medium showed intense enhancement of the mass on its surface and slightly less intensity in its central portion (figure 2).

[FIGURES 1-2 OMITTED]

The entire mass was removed surgically. A follow-up MRI 1 month later detected no residual tissue or recurrent lesion. Histologic examination identified the mass as an odontogenic myxoma. Clinically, the patient remained asymptomatic after 2 years.

Odontogenic myxomas usually originate on the maxilla or mandible, (2) and they affect the maxillofacial region. (3-5) They originate in the mesenchymal portion of the dental tissue, (6) probably at the dental papilla. (4 )Their benign characteristics notwithstanding, these tumors have a destructive, albeit slow, manner of growth. (3,7) Most of these lesions are asymptomatic, but they may cause pain and facial deformity as they grow. These symptoms develop secondary to expansion of the cortical bone and subsequent nerve compression, which can cause malocclusion and displacement of teeth. (3-5)

Histologically, odontogenic myxomas are relatively acellular. They are made up of loose myxomatous connective tissue, fibroblasts, myofibroblasts, and variable quantities of collagen in a mucopolysaccharide matrix. Patches of trabeculae of woven bone and capillaries are dispersed by the lesion. (2)

Other mesenchymal odontogenic tumors include fibromas, cementomas, and odontomas. The imaging differential diagnosis should include ameloblastoma, calcifying epithelial odontogenic tumor, ossifying fibroma, histiocytosis, osseous hemangioma, and giant-cell reparative granuloma. (2,7) Imaging examinations--including dental x-rays, CT, and MRI--clearly identify the nature of the expansile process. CT provides the best diagnostic information, but MRI may provide more specific information in some cases--for example, when one is trying to differentiate a benign mass from a malignant process or inflammatory processes involving the maxillary sinus.

References

(1.) Ries Centeno CM, Ostrosky AM, Nabim EF, et al. Mixoma del maxilar superior. Rev Assoc Odontol Argent 1993;81:247-50.

(2.) Keszler A, Dominguez FV, Giannunzio G. Myxomain childhood: An analysis of 10 cases. J Oral MaxiUofac Surg 1995;53(5):18-21.

(3.) Mosbiri S, Oda D, Worthington P, Myall R. Odontogenic myxoma: Histochemical and ultrastructural study. J Oral Pathol Med 1992; 21(9):401-3.

(4.) Green TL, Leigthy DM, Walters R. Immunohistochemical evaluation of oral myxoid lesions. Oral Surg Oral Med Oral Pathol 1992;73(4):469-71.

(5.) Lombardi T, Samson J, Bernard JE et al. Comparative immunohistochemical analysis between jaw myxoma and mesenchymal cells of tooth germ. Pathol Res Pract 1992;188(1-2):141-4.

(6.) Bucci E, Lo Muzio L, Mignogna MD, De Rosa G. Odontogenic myxoma: Report of a case with peculiar features. J Oral Maxillofac Surg 1991 ;49(1):91-4.

(7.) Oliver DS, DiNardo LJ, Monahan M, et al. Pathologic quiz case 2. Odontogenic fibromyxoma. Arch Otolaryngol Head Neck Surg 1995;121(7):805, 807.

Bernardo Boleaga-Duran, MD; Enrique Palacios, MD

From CT Scanner de Mexico, D.E Mexico (Dr. Boleaga-Duran), and the Department of Radiology, Tulane University Medical Center, New Orleans (Dr. Palacios).