Mandible & maxilla
Benign odontogenic tumors
Odontogenic myxoma / fibromyxoma
Last author update: 1 November 2017
Last staff update: 15 June 2023 (update in progress)
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PubMed Search: Odontogenic myxoma / myxofibroma
Table of Contents
Definition / general | Essential features | Terminology | Epidemiology | Sites | Clinical features | Diagnosis | Radiology description | Radiology images | Prognostic factors | Case reports | Treatment | Clinical images | Gross images | Microscopic (histologic) description | Microscopic (histologic) images | Positive stains | Negative stains | Molecular / cytogenetics description | Differential diagnosis | Board review style question #1 | Board review style answer #1Cite this page: Martinez A. Odontogenic myxoma / fibromyxoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/mandiblemaxillamyxoma.html. Accessed September 21st, 2023.
Definition / general
- Benign odontogenic neoplasm characterized by bland, spindled to stellate cells set in myxoid stroma
Essential features
- Benign odontogenic myxoid lesion composed of spindled to stellate cells
- Third most frequent odontogenic tumor (after odontoma and ameloblastoma)
- Recurrence rate ~25%
Terminology
- Odontogenic myxoma
- Odontogenic myxofibroma
- Odontogenic fibromyxoma
Epidemiology
- Most cases diagnosed in 2nd - 4th decades but wide age range of occurrence (between 1 to 73 years)
- More common in women
Sites
- More common in mandible than maxilla
- 2/3 in mandible
Clinical features
- Most patients are asymptomatic, usually incidental finding by imaging
- Can present with swelling
Diagnosis
- Diagnosis dependent on clinical, radiologic and pathologic correlation
Radiology description
- Radiographically, appear as radiolucent lesions that can be uni or multilocular creating a soap bubble or honeycomb appearance
- Cortical peforation can be seen
Radiology images
Images hosted on other servers:
Multilocular, radiolucent lesion
Right mandibular lateral occlusal view
Multilocular radiolucent osteolytic lesion
CT Scan of mandible
Prognostic factors
- ~25% recurrence rate, usually after incomplete excision
Case reports
- 13 year old boy with recurrence of an odontogenic myxoma of the mandible (Saudi Dent J 2017;29:93)
- 18 year old woman with swelling on lower right side of face since 6 months (J Clin Diagn Res 2016;10:ZJ05)
- 18 year old man with odontogenic myxoma of the maxilla (J Clin Diagn Res 2015;9:ZD29)
- 48 year old woman with gradually increasing swelling of right lower front tooth region (J Clin Diagn Res 2016;10:ZD30)
Treatment
- Surgery is mainstay of treatment
- Smaller lesions often treated with curettage
- Larger lesions with complete excision
Clinical images
Images hosted on other servers:
Swelling on the right side
Mandibular right quadrant
Gross images
Images hosted on other servers:
Gray white appearance
Jelly-like appearance
Microscopic (histologic) description
- Spindled to stellate cells with eosinophilic cytoplasm set in myxoid matrix
- Binucleated heart shaped cells, mitoses and minimal atypia can be seen
- If abundant collagen present, the term "myxofibroma" or "fibromyxoma" has been used
- Occasional scattered epithelial rests can be seen
Microscopic (histologic) images
Contributed by Kelly Magliocca D.D.S., M.P.H.
Odontogenic myxoma / myxofibroma
Mandibular odontogenic myxoma
Images hosted on other servers:
H&E
Spindle shaped cells with long cytoplasmic processes
H&E 100x
Positive stains
- Orosomucoid 1 protein (ORM-1)
- SMA
Negative stains
Molecular / cytogenetics description
- Decreased immunostaining for the protein product and occasional mutations of the PRKAR1A gene have been identified (Genes Chromosomes Cancer 2005;44:204)
- Likely represent sporadic mutations and not those seen in Carney complex (CNC)
- Odontogenic myxomas do not appear to be associated with GNAS1 mutations like those seen in Mazabraud syndrome
Differential diagnosis
- Based on histology of spindled cells with myxoid / fibromyxoid stroma
- Dental papilla
- Immature dental pulp from a developing tooth can be mistaken for a myxoma
- Have a rim of odontoblasts / epithelium, myxomas do not have this
- Chondromyxoid fibroma
- Have stellate cells, but they tend to be more uniform and the lesion is often lobulated, and hypocellular centrally and hypercellular at the periphery
- Often scattered giant cells at the periphery
- Calcification and hyaline cartilage can be variably present
- Odontogenic fibroma
- Similar peak age of presentation
- Can also have spindled cells but usually more cellular and fibrocollagenous with strands of odontogenic epithelium
- Calcifications can be seen in the epithelium
- Osteochondromyxoma
- Usually present in a younger age group with the nasal cavity being the most common site
- Can also have stellate cells in a myxoid stroma
- Tend to grow in a lobulated pattern with cementoid hyaline bodies similar to unicameral bone cyst
- Can show loss of PRKAR1A as the majority of the cases are associated with Carney complex
- Based on radiology
- Other odontogenic cysts
- Other benign and malignant odontogenic tumors
- Dental papilla
Board review style question #1
Odontogenic myxomas are known to be associated with which syndrome?
- Carney complex
- Mazabraud syndrome
- Both Mazabraud syndrome and Carney complex
- None of the above
Board review style answer #1
