Ameloblastic fibroma

Last updated
Ameloblastic fibroma
Enamelmineralization11-17-05.jpg
Histology of developing tooth with enamel, dentin, ameloblasts, and odontoblasts labeled. Tooth bud is in maturation/crown stage.
Symptoms Painless swelling of the jaw. [1]
Complications Impacted tooth. [1]
Usual onsetChildhood or adolescence. [1]
Diagnostic method Dental radiograph. [1]
Differential diagnosis Ameloblastic fibro-odontoma or odontoma. [1]
TreatmentSurgical excision or curettage and removal of the effected teeth. [1]
Frequency2% of odontogenic tumors. [1]

An ameloblastic fibroma is a fibroma of the ameloblastic tissue, that is, an odontogenic tumor arising from the enamel organ or dental lamina. It may be either truly neoplastic or merely hamartomatous (an odontoma). In neoplastic cases, it may be labeled an ameloblastic fibrosarcoma in accord with the terminological distinction that reserves the word fibroma for benign tumors and assigns the word fibrosarcoma to malignant ones. It is more common in the first and second decades of life, when odontogenesis is ongoing, than in later decades. In 50% of cases an unerupted tooth is involved.

Contents

Histopathology alone is usually not enough to differentiate neoplastic cases from hamartomatous ones, because the histology is very similar. Other clinical and radiographic clues are used to narrow the diagnosis.

Clinical Features

Ameloblastic fibroma is a rare benign mixed epithelial and mesenchymal odontogenic tumour as it contributes to approximately 2% of all odontogenic tumours. It often occurs in the first or second decade of life. Ameloblastic fibroma usually appears as painless swelling of the jaw in the posterior region of the mandible. [2] It can be associated with an impacted toot h [3] and it might impede eruption of other teeth. The lesion can be asymptomatic when it is small and most are incidental findings of routine dental radiographic imaging, etc. [3] [4]

Diagnosis

Radiographic Features

Radiographically, ameloblastic fibroma has a variable appearance. It can appear as a unilocular lesion with smooth, well-defined margin when smaller. However, it can be multilocular when it is enlarged. It can be mistaken as dentigerous cyst as the lesion is often associated with an impacted tooth. [1] [4]

Histopathology

The histopathology of ameloblastic fibromas resembles the stages of normal tooth development. [5] These mixed lesions consist of histologically distinct epithelial and mesenchymal tissues. [6] The epithelial tissue resembles dental lamina and enamel organ tissues, while the mesenchyme resembles the dental papilla. [7]

The epithelial component features strands which branch and join, or anastomose. This results in knots of differing mass, resembling islands in a loose stroma. [7] Cells in the strands tend to be cuboidal, but where budding occurs from the strands the knots resemble tooth caps. The bud-cap stage of normal development shows ameloblasts forming palisades of columnar cells adjacent to a starry-like, loosely formed layer known as stellate reticulum. [8] However, the pattern of budding strands is distinctive from normal development. [7] The Ameloblastic Fibroma epithelial tissue could be confused with the most common odontogenic tumour, the Ameloblastoma. Therefore the mesenchymal component is histologically important in differential diagnosis. [7]

The mesenchymal stroma in normal development is a rich myxoid connective tissue. It gives rise to the dental follicle which encapsulates the developing tooth. [8] In Ameloblastoma the stroma is mature, often fibrous. This is distinct from the mesenchymal element of Ameloblastic Fibroma which is devoid of collagen. [2] The Ameloblastic Fibroma stroma remains primitive, undifferentiated, cell-rich and myxoid. [7] Rarely, it may contain granular cells. However, it should be noted this may also be observed in a hyperplastic dental follicle, and therefore other histological and radiological diagnostic features should be observed. [9]

The malignant ameloblastic fibroma will have features of malignant transformation such as mitotic figures in either epithelial or mesenchymal tissue. [8] There is a resemblance to fibrosarcoma. The malignant Ameloblastic Fibroma histologically shows transformation in the mesenchymal component with increased cellularity, accompanied by a progressive reduction in epithelial tissue. [1]

Classification

An ameloblastic fibroma is classified by The World Health Organisation as a benign mixed odontogenic tumour. [2] It develops from the dental tissues that grow into teeth.  During human development, embryonic cells of ectoderm and mesenchyme produce epithelial and ectomesenchyme tissues. These proliferate and mature into ameloblasts and fibrous connective tissue, [4] and ultimately teeth. Ameloblastic fibromas contain both of these tissues, and its name is derived from them. It is a neoplasm, meaning it is a mass of abnormal growth of cells or tissue.  If the mass contains hard dental tissues they are known as odontoma, which are not true neoplasm, but classified as hamartomatous lesions. [1]

Treatments

As ameloblastic fibromas are rare and the literature regarding treatment is limited there is controversy regarding treatment approach. A conservative treatment strategy, such as enucleation and curettage, is usually sufficient for small ameloblastic fibromas. However, extensive and aggressive lesions may require radical treatment such as in older patients who have likely high recurrence tendency.

If the ameloblastic fibroma is small, ‘reconstruction’ will not be required. Conservative treatment usually involves enucleation and thorough curettage of the affected area alongside extraction of the affected teeth. [1] Enucleation is the removal of an organ or tumor in such a way that it comes out clean and whole. [9] Thorough enucleation is important as there are reports of a high recurrence rate (Trodahl reported a 36.4% recurrence rate). [5] Immediate reconstruction is required post enucleation and curettage of the affected area. [6] Some patients may require reconstruction which can include a full thickness bone graft. This treatment allows the patient to retain oral function and as much facial structure as possible.  

Occasionally, more radical treatment is required with excision of the tumour with a margin of healthy tissue. [8]

This kind of treatment also requires reconstruction of the affected area, with bone grafts often being the preferred choice for remodelling. This is done when the tumour is large or is deemed to have a high chance of malignant transformation. [7] In some cases the fibroma may envelop a nerve and may have to be removed too. [10]

Implants in compromised areas filled with a bone graft can prove useful for functional and aesthetic stability. Implant retained prosthesis can be placed and can make a vital overall functional and masticatory difference. [11]

Close radiographic and clinical follow up is important to identify recurrence and malignant transformation. [10]

Epidemiology

Odontogenic tumours are uncommon, with a prevalence of around 2% [9] and only 1-2% of these are ameloblastic fibromas. [5] As they are rare, there is limited evidence available, mostly case studies. There is a slight male predilection, developing most commonly within the first two decades of life. They are often identified when tooth development is complete with the posterior mandible being the most common site. Although benign, ameloblastic fibromas that occur in later decades as well as a third of treated ameloblastic fibromas can recur and around 11% may undergo malignant transformation, though this figure is questioned. [1] [6] Odontoma are the most prevalent of the odontogenic tumours in the early decades and ameloblastic fibromas diagnosis should be considered.

See also

Related Research Articles

<span class="mw-page-title-main">Fibroadenoma</span> Medical condition

Fibroadenomas are benign breast tumours characterized by an admixture of stromal and epithelial tissue. Breasts are made of lobules and ducts. These are surrounded by glandular, fibrous and fatty tissues. Fibroadenomas develop from the lobules. The glandular tissue and ducts grow over the lobule to form a solid lump.

<span class="mw-page-title-main">Enamel organ</span> Aggregate of cells involved in tooth development

The enamel organ, also known as the dental organ, is a cellular aggregation seen in a developing tooth and it lies above the dental papilla. The enamel organ which is differentiated from the primitive oral epithelium lining the stomodeum. The enamel organ is responsible for the formation of enamel, initiation of dentine formation, establishment of the shape of a tooth's crown, and establishment of the dentoenamel junction.

<span class="mw-page-title-main">Ameloblastoma</span> Medical condition

Ameloblastoma is a rare, benign or cancerous tumor of odontogenic epithelium much more commonly appearing in the lower jaw than the upper jaw. It was recognized in 1827 by Cusack. This type of odontogenic neoplasm was designated as an adamantinoma in 1885 by the French physician Louis-Charles Malassez. It was finally renamed to the modern name ameloblastoma in 1930 by Ivey and Churchill.

<span class="mw-page-title-main">Cementoblastoma</span> Medical condition

Cementoblastoma, or benign cementoblastoma, is a relatively rare benign neoplasm of the cementum of the teeth. It is derived from ectomesenchyme of odontogenic origin. Cementoblastomas represent less than 0.69–8% of all odontogenic tumors.

The oral mucosa is the mucous membrane lining the inside of the mouth. It comprises stratified squamous epithelium, termed "oral epithelium", and an underlying connective tissue termed lamina propria. The oral cavity has sometimes been described as a mirror that reflects the health of the individual. Changes indicative of disease are seen as alterations in the oral mucosa lining the mouth, which can reveal systemic conditions, such as diabetes or vitamin deficiency, or the local effects of chronic tobacco or alcohol use. The oral mucosa tends to heal faster and with less scar formation compared to the skin. The underlying mechanism remains unknown, but research suggests that extracellular vesicles might be involved.

<span class="mw-page-title-main">Dentigerous cyst</span> Medical condition

A dentigerous cyst, also known as a follicular cyst, is an epithelial-lined developmental cyst formed by accumulation of fluid between the reduced enamel epithelium and the crown of an unerupted tooth. It is formed when there is an alteration in the reduced enamel epithelium and encloses the crown of an unerupted tooth at the cemento-enamel junction. Fluid is accumulated between reduced enamel epithelium and the crown of an unerupted tooth.

<span class="mw-page-title-main">Central giant-cell granuloma</span> Medical condition

Central giant-cell granuloma (CGCG) is a localised benign condition of the jaws. It is twice as common in females and is more likely to occur before age 30. Central giant-cell granulomas are more common in the anterior mandible, often crossing the midline and causing painless swellings.

<span class="mw-page-title-main">Odontogenic keratocyst</span> Medical condition

An odontogenic keratocyst is a rare and benign but locally aggressive developmental cyst. It most often affects the posterior mandible and most commonly presents in the third decade of life. Odontogenic keratocysts make up around 19% of jaw cysts.

Lateral periodontal cysts (LPCs) are defined as non-keratinised and non-inflammatory developmental cysts located adjacent or lateral to the root of a vital tooth.” LPCs are a rare form of jaw cysts, with the same histopathological characteristics as gingival cysts of adults (GCA). Hence LPCs are regarded as the intraosseous form of the extraosseous GCA. They are commonly found along the lateral periodontium or within the bone between the roots of vital teeth, around mandibular canines and premolars. Standish and Shafer reported the first well-documented case of LPCs in 1958, followed by Holder and Kunkel in the same year although it was called a periodontal cyst. Since then, there has been more than 270 well-documented cases of LPCs in literature.

<span class="mw-page-title-main">Calcifying odontogenic cyst</span> Medical condition

Calcifying odontogenic cyst (COC) is a rare developmental lesion that comes from odontogenic epithelium. It is also known as a calcifying cystic odontogenic tumor, which is a proliferation of odontogenic epithelium and scattered nest of ghost cells and calcifications that may form the lining of a cyst, or present as a solid mass.

<span class="mw-page-title-main">Glandular odontogenic cyst</span> Human jaw cyst

A glandular odontogenic cyst (GOC) is a rare and usually benign odontogenic cyst developed at the odontogenic epithelium of the mandible or maxilla. Originally, the cyst was labeled as "sialo-odontogenic cyst" in 1987. However, the World Health Organization (WHO) decided to adopt the medical expression "glandular odontogenic cyst". Following the initial classification, only 60 medically documented cases were present in the population by 2003. GOC was established as its own biological growth after differentiation from other jaw cysts such as the "central mucoepidermoid carcinoma (MEC)", a popular type of neoplasm at the salivary glands. GOC is usually misdiagnosed with other lesions developed at the glandular and salivary gland due to the shared clinical signs. The presence of osteodentin supports the concept of an odontogenic pathway. This odontogenic cyst is commonly described to be a slow and aggressive development. The inclination of GOC to be large and multilocular is associated with a greater chance of remission. GOC is an infrequent manifestation with a 0.2% diagnosis in jaw lesion cases. Reported cases show that GOC mainly impacts the mandible and male individuals. The presentation of GOC at the maxilla has a very low rate of incidence. The GOC development is more common in adults in their fifth and sixth decades.

Squamous odontogenic tumors (SOTs) are very rare benign locally infiltrative odontogenic neoplasms of epithelial origin. Only some 50 cases have been documented. They occur mostly from 20-40 and are more common in males. Treatment is by simple enucleation and local curettage, and recurrence is rare.

<span class="mw-page-title-main">Odontoma</span> Benign tumour of dental tissue

An odontoma, also known as an odontome, is a benign tumour linked to tooth development. Specifically, it is a dental hamartoma, meaning that it is composed of normal dental tissue that has grown in an irregular way. It includes both odontogenic hard and soft tissues. As with normal tooth development, odontomas stop growing once mature which makes them benign.

The calcifying epithelial odontogenic tumor (CEOT), also known as a Pindborg tumor, is an odontogenic tumor first recognized by the Danish pathologist Jens Jørgen Pindborg in 1955. It was previously described as an adenoid adamantoblastoma, unusual ameloblastoma and a cystic odontoma. Like other odontogenic neoplasms, it is thought to arise from the epithelial element of the enamel origin. It is a typically benign and slow growing, but invasive neoplasm.

<span class="mw-page-title-main">Cementoma</span> Medical condition

Cementoma is an odontogenic tumor of cementum. It is usually observed as a benign spherical mass of hard tissue fused to the root of a tooth. It is found most commonly in the mandible in the region of the lower molar teeth, occurring between the ages of 8 and 30 in both sexes with equal frequency. It causes distortion of surrounding areas but is usually a painless growth, at least initially. Considerable thickening of the cementum can often be observed. A periapical form is also recognized. Cementoma is not exclusive to the mandible as it can infrequently occur in the maxilla and other parts of the body such as the long bones.

An odontogenic tumor is a neoplasm of the cells or tissues that initiate odontogenic processes.

A ghost cell is an enlarged eosinophilic epithelial cell with eosinophilic cytoplasm but without a nucleus.

Odontogenic cyst are a group of jaw cysts that are formed from tissues involved in odontogenesis. Odontogenic cysts are closed sacs, and have a distinct membrane derived from rests of odontogenic epithelium. It may contain air, fluids, or semi-solid material. Intra-bony cysts are most common in the jaws, because the mandible and maxilla are the only bones with epithelial components. That odontogenic epithelium is critical in normal tooth development. However, epithelial rests may be the origin for the cyst lining later. Not all oral cysts are odontogenic cysts. For example, mucous cyst of the oral mucosa and nasolabial duct cyst are not of odontogenic origin.

A cyst is a pathological epithelial lined cavity that fills with fluid or soft material and usually grows from internal pressure generated by fluid being drawn into the cavity from osmosis. The bones of the jaws, the mandible and maxilla, are the bones with the highest prevalence of cysts in the human body. This is due to the abundant amount of epithelial remnants that can be left in the bones of the jaws. The enamel of teeth is formed from ectoderm, and so remnants of epithelium can be left in the bone during odontogenesis. The bones of the jaws develop from embryologic processes which fuse, and ectodermal tissue may be trapped along the lines of this fusion. This "resting" epithelium is usually dormant or undergoes atrophy, but, when stimulated, may form a cyst. The reasons why resting epithelium may proliferate and undergo cystic transformation are generally unknown, but inflammation is thought to be a major factor. The high prevalence of tooth impactions and dental infections that occur in the bones of the jaws is also significant to explain why cysts are more common at these sites.

The ameloblastic fibro-odontoma (AFO) is essentially a benign tumor with the features characteristic of ameloblastic fibroma along with enamel and dentin. Though it is generally regarded as benign, there have been cases of its malignant transformation into ameloblastic fibrosarcoma and odontogenic sarcoma. Cahn LR and Blum T, believed in "maturation theory", which suggested that AFO was an intermediate stage and eventually developed during the period of tooth formation to a complex odontoma thus, being a hamartoma.

References

  1. 1 2 3 4 5 6 7 8 9 10 11 12 Nelson, Brenda L.; Folk, Gretchen S. (March 2009). "Ameloblastic Fibroma". Head and Neck Pathology. 3 (1): 51–53. doi:10.1007/s12105-008-0091-0. ISSN   1936-055X. PMC   2807540 . PMID   20596990.
  2. 1 2 3 Ponnam, SrinivasRao; Srivastava, Gautam; Smitha, B (2012). "Ameloblastic fibroma". Journal of Oral and Maxillofacial Pathology. 16 (3): 444–5. doi: 10.4103/0973-029X.102515 . ISSN   0973-029X. PMC   3519228 . PMID   23248485.
  3. 1 2 Ealla, Kranti Kiran Reddy; Basavanapalli, Vijayabaskar Reddy; Velidandla, Surekha Reddy; Manikya, Sangameshwar; Ragulakollu, Rajesh; Danappanavar, Prasanna M.; Vennila, Vijayasree (2015). "Ameloblastic Fibroma of the Maxilla with Bilateral Presentation: Report of a Rare Case with Review of the Literature". Case Reports in Pediatrics. 2015: 250713. doi: 10.1155/2015/250713 . PMC   4299785 . PMID   25628911.
  4. 1 2 3 Odell, E. W. (2017). Cawson's essentials of oral pathology and oral medicine. Preceded by (work): Cawson, R. A. (Ninth ed.). [Edinburgh]. ISBN   978-0-7020-4982-8. OCLC   960030340.{{cite book}}: CS1 maint: location missing publisher (link)
  5. 1 2 3 Tozoglu, S.; Hatipoglu, M.; Aytekin, Z.; Gurer, E. I. (2016). "Europe PMC". European Journal of Dentistry. 10 (1): 139–143. doi: 10.4103/1305-7456.175700 . PMC   4784144 . PMID   27011753.
  6. 1 2 3 Vasconcelos, Belmiro C. E.; Andrade, Emanuel S. S.; Rocha, Nelson S.; Morais, Hécio H. A.; Carvalho, Ricardo W. F. (June 2009). "Treatment of large ameloblastic fibroma: a case report". Journal of Oral Science. 51 (2): 293–296. doi: 10.2334/josnusd.51.293 . ISSN   1880-4926. PMID   19550100.
  7. 1 2 3 4 5 6 Baris Bingül, Kenan (2017-08-24). "Review of 101 benign epithelial, mesencymal and mixed odontogenic tumours". doi:10.26226/morressier.596dfd58d462b80292387c8c.{{cite journal}}: Cite journal requires |journal= (help)
  8. 1 2 3 4 Chrcanovic, Bruno Ramos; Brennan, Peter A.; Rahimi, Siavash; Gomez, Ricardo Santiago (April 2018). "Ameloblastic fibroma and ameloblastic fibrosarcoma: A systematic review". Journal of Oral Pathology & Medicine. 47 (4): 315–325. doi:10.1111/jop.12622. hdl: 2043/23318 . ISSN   1600-0714. PMID   28776760. S2CID   4873133.
  9. 1 2 3 "NCI Dictionary of Cancer Terms". National Cancer Institute. 2011-02-02. Retrieved 2020-03-05.
  10. 1 2 Carroll, Conor; Gill, Mishaal; Bowden, Eleanor; O’Connell, John Ed; Shukla, Rajeev; Sweet, Chris (2019). "Ameloblastic Fibroma of the Mandible Reconstructed with Autogenous Parietal Bone: Report of a Case and Literature Review". Case Reports in Dentistry. 2019: 5149219. doi: 10.1155/2019/5149219 . PMC   6604494 . PMID   31316839.
  11. Mishra, Niraj; Pal, Umashankar (2012). "Placement of implants in an ossifying fibroma defect obliterated with demineralized, freeze-dried bone allograft and Plasma-rich growth factor". Contemporary Clinical Dentistry. 3 (4): 471–4. doi: 10.4103/0976-237X.107444 . ISSN   0976-237X. PMC   3636830 . PMID   23633812.

Further reading