Odontogenic Myxoma

Arch Pathol Lab Med. 2006 Dec;130(12):1799-806. Abstract quote

CONTEXT: Odontogenic myxoma is an uncommon tumor that has the potential for extensive destruction of the jaws.

OBJECTIVE: To document the clinical, pathologic, and behavioral features of odontogenic myxomas.

DESIGN: Histologic and immunocytochemical examinations were performed on odontogenic myxomas from 25 Chinese patients. Clinical and available follow-up data were analyzed.

RESULTS: In the present series, 13 were male and 12 female. The age at diagnosis ranged from 6 to 66 years, with a mean age of 28.8 years. Twelve tumors involved the mandible and 13 occurred in the maxilla, with a predilection for posterior areas. The posterior maxillary tumors frequently (9/10) involved the maxillary sinus. Of the 23 cases with radiographic records, 22 lesions presented with a multilocular appearance. Although 80% of the mandibular lesions showed a well-defined border, only 33.3% of the maxillary tumors were well-defined. Histologically, odontogenic myxomas were mainly composed of spindled or stellate-shaped cells in a mucoid-rich intercellular matrix. Tumors containing noticeable fibrous components were evident in 13 cases. Apart from 5 cases treated conservatively by enucleation, the remaining 20 cases were treated by relatively radical procedures, including block/segmental resection and partial or total maxillectomy or mandibulectomy. Follow-up data were available on 22 patients and only 1 patient initially treated by enucleation had a recurrence.

CONCLUSIONS: Odontogenic myxomas have a very bland histologic appearance that lacks atypia and may easily lead to misdiagnosis. The tumors are infiltrative with no capsulation and may recur after inadequate surgery.

Epidemiology
Disease Associations
Pathogenesis
Laboratory/Radiologic/ Other Diagnostic Testing
Gross Appearance and Clinical Variants
Histopathological Features and Variants
Special Stains/ Immunohistochemistry/ Electron Microscopy
Differential Diagnosis
Prognosis
Treatment
Commonly Used Terms
Internet Links

EPIDEMIOLOGY	CHARACTERIZATION
SYNONYMS	Myxofibroma
INCIDENCE	1-17.7% of all odontogenic tumors
AGE RANGE-MEDIAN	Most common in second-third decades Range 5-72 years
SEX (M:F)	Probably female favored
GEOGRAPHY	May vary widely in incidence

PATHOGENESIS	CHARACTERIZATION
Probably derived from ectomesenchyme	Most myxomas arise from tooth-bearing areas of the jaw

GROSS APPEARANCE/ CLINICAL VARIANTS	CHARACTERIZATION
General	May favor maxilla over mandible Posterior lesions in the maxilla and mandible tend to be larger and more aggressive
Odontogenic myxoma: a clinicopathologic study of 25 cases. Li TJ, Sun LS, Luo HY. Department of Oral Pathology, School and Hospital of Stomatology, Peking University, 22 S Zhongguancun Ave, Haidian District, Beijing, PR China 100081.	Arch Pathol Lab Med. 2006 Dec;130(12):1799-806. Abstract quote CONTEXT: Odontogenic myxoma is an uncommon tumor that has the potential for extensive destruction of the jaws. OBJECTIVE: To document the clinical, pathologic, and behavioral features of odontogenic myxomas. DESIGN: Histologic and immunocytochemical examinations were performed on odontogenic myxomas from 25 Chinese patients. Clinical and available follow-up data were analyzed. RESULTS: In the present series, 13 were male and 12 female. The age at diagnosis ranged from 6 to 66 years, with a mean age of 28.8 years. Twelve tumors involved the mandible and 13 occurred in the maxilla, with a predilection for posterior areas. The posterior maxillary tumors frequently (9/10) involved the maxillary sinus. Of the 23 cases with radiographic records, 22 lesions presented with a multilocular appearance. Although 80% of the mandibular lesions showed a well-defined border, only 33.3% of the maxillary tumors were well-defined. Histologically, odontogenic myxomas were mainly composed of spindled or stellate-shaped cells in a mucoid-rich intercellular matrix. Tumors containing noticeable fibrous components were evident in 13 cases. Apart from 5 cases treated conservatively by enucleation, the remaining 20 cases were treated by relatively radical procedures, including block/segmental resection and partial or total maxillectomy or mandibulectomy. Follow-up data were available on 22 patients and only 1 patient initially treated by enucleation had a recurrence. CONCLUSIONS: Odontogenic myxomas have a very bland histologic appearance that lacks atypia and may easily lead to misdiagnosis. The tumors are infiltrative with no capsulation and may recur after inadequate surgery.

SPECIAL STAINS/ IMMUNOPEROXIDASE/ OTHER	CHARACTERIZATION
Tumor cells positive	Vimentin Patchy muscle specific actin S100-possible
Tumor cells negative	Cytokeratin NSE

DIFFERENTIAL DIAGNOSIS	KEY DIFFERENTIATING FEATURES
Dental follicles	More collagenous with clusters of reduced enamel epithelium
Dental papillae or future pulp	Loose myxoid tissue with peripheral areas containing columnar odontoblasts and fragments of dentin

PROGNOSIS AND TREATMENT	CHARACTERIZATION
Prognostic Factors	Adequacy of initial treatment is most important
Metastasis	None Recurrence ranging from 10-33% Higher recurrence in conservative treatment
Treatment
Small tumors	Currettage
Large tumors	Enucleation with currettage of surrounding bone Resection may be considered