Resident: Cho
Author(s): Harokopakis-Hajishengallis E, et al.
Journal: Pediatric Dentistry
Year. Volume (number). Page #’s: 2007. 29. 409-414.
Major topic: Odontogenic Myxoma
Type of Article: Case Report
Key points/Summary:
Myxoma: benign soft tissue or bone neoplasm that may appear anywhere in the body.
Most central myxomas occur in the jaws where they are called odontogenic myxomas (OM) because of their presumably odontogenic origin although their histologic origin is still controversial.
OM is a rare neoplasm with an annual incidence of 0.07 per million. Among other odontogenic tumors, however, OM is the second most common following ameloblastoma. OM should be considered in the radiographic differential dx. of dentigerous cyst, odontogenic keratocyst, ameloblastoma, central giant cell granuloma, central hemangioma, traumatic bone cyst, aneurysmal bone cysts, or fibrous dysplasia. OM is most commonly seen between ages of 10 and 40 years of age (young adult).
OM occurs in both the maxilla and mandible and is usually unilateral – rarely crosses the midline. Posterior region of the jaw is the most common site. 5% of the cases is associated with an unerupted tooth.
OM is a locally invasive lesion that grows slowly and generally without significant symptoms. On average, there is a delay of 1 to 5 years form the lesion’s onset to the first sign, which is usually a slow growing facial or intraoral swelling that causes the patient to seek medical help. Involved teeth may become mobile and malpositioned, but they remain viable. Symptoms such as nasal obstruction, diplopia, pain, or paresthesia may develop upon bony perforation and invasion in the maxillary sinus, palate, orbit, and nasal cavity.
Radiographically, OM commonly presents as unilocular or multilocular, well-defined radiolocuency with “soap-bubble” or “tennis racquet” appearance. The “tennis racquet” appearance is almost pathognomonic of OM but only is seen in 1/3 of the cases. OM is associated with tooth displacement in 26% of the cases and/or root resorption in up to 50% of the cases.
Upon gross examination, OM appears as a white or yellow, gelatinous lobulated mass. Histologically, it is composed of spindle-shaped and stellate cells interspersed in the loose mucoid background. Odontogenic epithelium may or may not be found.
The generally accepted treatment of OM includes resection of the tumor with a greater than 1.5cm margin of the surrounding tissue to prevent recurrence. The overall prognosis for OM is generally good – average recurrence rate is 25%. Recurrence usually occurs during the first 2 years after treatment. Malignant transformation is extremely rare and metastasis has not been reported.
CASE REPORT
Healthy 6-year, 11-month female with unremarkable medical history, no dental caries, normal complement of teeth for her age presents on radiographic exam with bifurcation radiolucency and root resorption around #J, poorly defined radiolucency in the furcation of #J, unerupted #13 displaced superiorly.
#J was extracted and incisional biopsy performed. Microscopic exam of excised mucoid soft tissue provided histopathologic diagnosis of odontogenic myxoma. It showed stellate-shaped fibroblastic cells interspersed in matrix blue ground substance.
Upon CT, the lesion presented as a single unilocular radiolucency with well-defined scalloped borders located superior to extraction socket of #J. Adjacent to unerupted #13, it had caused buccal expansion, thinning, and convexity of the inferior floor of the maxillary sinus. The mass was surgically excised in the OR. The buccal cortex surrounding the lesion was removed and the tumor was enucleated without difficulty. #14, unerupted #12, unerupted #13, and #I were all extracted due to being inside the tumor bed or close to the tumor bed. 9 months following the lesion’s excision, the patient has shown no evidence of recurrence.
Assessment of Article: Excellent article. Learned a lot and thought that it gave a very thorough description of odontogenic myxomas.
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