What Is an Adenomatoid Odontogenic Tumor?
An adenomatoid odontogenic tumor (AOT) is a significant benign tumor of the jaws, occurring mostly in the maxilla, as an asymptomatic swelling. These lesions mainly affect younger patients and are mostly associated with an impacted canine. Certain case reports suggest this tumor can also occur in relation to other impacted teeth. An adenomatoid odontogenic tumor (AOT) was originally described by Ghosh in the year 1934. Initially, it was described as an Adamantinoma that occurred in relation to the maxillary canine but was later recognized to possess rather distinct features and was classified as distinct yet benign by Stafne in 1948. This benign jaw tumor is denoted by various names such as:
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Adenoameloblastoma.
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Cystic complex composite odontoma.
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Ameloblastic odontogenic tumor.
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Odontogenic adenomatoid tumor.
Why Is It Called Two-Third Tumor?
AOT is a benign tumor that occurs in about three to seven percent of all odontogenic tumors of the jaw, usually in the second decade of life. This tumor is also referred to as a two-third tumor because it mostly occurs in the maxilla in about two-third of all cases, mostly two-third cases in young females, and two-third of cases are associated with an impacted tooth. This tumor occurs only in relation to the tooth-bearing areas of the jaw and not otherwise.
How Does an Adenomatoid Odontogenic Tumor Occur?
The origin of AOT is exactly unknown. However, many researchers believe in the possibility of an odontogenic source that may persist in causing this jaw tumor. The cytological components of this tumor may be numerous, like the enamel organ, dental lamina, reduced enamel epithelium, or even its remnants in the jaw.
What Are the Other Conditions Similar to an Adenomatoid Odontogenic Tumor?
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Odontogenic keratocyst.
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Unicystic ameloblastoma.
How Can Adenomatoid Odontogenic Tumors Be Diagnosed?
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Radiographically, the tumors resemble that of the dentigerous cyst. These lesions are unilocular, and appear radiolucent. The characteristic fine calcifications or snowflake appearance is usually seen in a radiograph which differentiates AOT from a dentigerous cyst and other odontogenic tumors.
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A biopsy tissue of AOT reveals a very well-developed connective tissue capsule around the solid tumor mass. It is seen as a large cystic space, usually single or sometimes comprising multiple small cystic spaces inside. The tumor is called so because of its characteristic duct-like structures. The spindle-shaped or polygonal cells form sheet patterns and are seen as masses within a connective tissue stroma.
What Are the Different Variants of AOT?
These tumors may be partially cystic or appear as large cysts containing very small masses. These tumors can be subdivided into three major variants of groups based on their histologic features such as follicular, extrafollicular, and peripheral patterns of AOT. The common histologic features in all three variants denote the origin of these tumors from dental lamina or its remnants. The follicular and extrafollicular variants are the most commonly observed AOT tumors (approximately 96 percent), and a peripheral variant of AOT is rarely reported. The follicular variant would usually be associated with both the tooth crown and a portion of the impacted or unerupted root of the tooth involved, commonly the canine of the upper jaw, and in some rare cases, molars.
How Can Adenomatoid Odontogenic Tumors Be Managed?
The management of AOT jaw tumors is by an enucleation procedure, which eliminates the lesion completely. Adenomatoid odontogenic tumors have no scope for malignancy (cancerous potential) as they are completely encapsulated lesions. However, when the dental follicle is involved, the impacted tooth might need to be extracted to eliminate the cyst and prevent its recurrence. When the tumor size is large, or the lesion closely approximates the unerupted or impacted tooth, then restoring the tooth may not be possible. As AOT lesions are not aggressive and also generally have low recurrence rates, it has an excellent prognosis post-removal or enucleation surgery.
Conclusion:
The adenomatoid odontogenic tumor is a rare, benign, and asymptomatic tumor, often resembling a cyst. It usually affects young adults and is associated mostly with an impacted canine. However, these lesions are non-invasive, recurrence is uncommon, and can be managed by enucleation, with an excellent prognosis.
