Ameloblastoma (from the earliest English word amel , meaning the Greek word enamel
Although these tumors are rarely malignant or metastatic (ie rarely spread to other parts of the body), and develop slowly, the resulting lesions can cause severe abnormalities in the face and jaw. In addition, because abnormal cell growth easily infiltrates and destroys surrounding bone tissue, wide surgical excision is required to treat the disorder. If the aggressive tumor is not treated, it can block the nasal and mouth passages so that it is not possible to breathe without oropharyngeal intervention.
Video Ameloblastoma
Fitur klinis
Ameloblastoma is often associated with the presence of unerupted teeth. Symptoms include painless swelling, facial deformity if severe enough, pain if swelling affects other structures, loose teeth, ulcers, and periodontal disease (gums). Lesions will occur in the lower jaw and upper jaw, although 75% occur in the asus ramus area and will result in a wide and dire abnormality of the jaw and upper jaw. In the upper jaw it can extend into the maxillary sinus and the floor of the nose. Lesions have a tendency to expand the bone cortex because the slow growth rate of the lesion allows time for the periosteum to develop a thin bone shell prior to an enlarged lesion. This bone shell is cracked when palpated and the phenomenon is referred to as "Cracking Egg Crackers" or crepitations, an important diagnostic feature. Ameloblastoma is temporarily diagnosed by radiographic examination and should be confirmed by histological examination (eg, biopsy).
Maps Ameloblastoma
Histopathology
Histopathology will show cells that have a tendency to move the nucleus away from the basement membrane. This process is referred to as "Reverse Polarization". The follicular type will have an outer arrangement of colloidal or palisaded amyloblasts such as cells and zones in triangular cells that resemble the stellate reticulum at the bell stage. The central cells sometimes degenerate to form the central microcysts. This type of plexiform has epithelium proliferating in "Clean Fish Pattern". Plexiform amyloblastoma shows epithelium proliferating with a 'fashion-like rope', so it is called a 'plexiform'. There is a layer of cells between the epithelium that proliferates with a well-formed desmosomal joint, which simulates the spindle cell layer.
Variant
The six different histopathological variants of ameloblastoma are desmoplastic, granular cells, basal cells, plexiforms, follicles, and acanthomatous.
Acanthomatous variants are very rare.
One-third of ameloblastomas are plexiforms, one-third are follicles. Other variants such as acanthomatous occur in older patients. At one center, desmoplastic amyobastoma represents about 9% of all ameloblastomas encountered.
The variant of adenoid ameloblastoma was recently introduced, but it is still very rare.
Diagnosis
Radiographically, it appears as a lucency in bone with varying sizes and features - sometimes it is a well-defined single lesion while often showing as a multiloculated "soap bubble" appearance. The root resorption of involved tooth can be seen in some cases, but not unique to ameloblastoma. The disease is most commonly found in the posterior body and mandibular angle, but can occur anywhere either in the upper jaw or lower jaw.
Radiodensity of amelioblastoma is about 30 units of Hounsfield, which is almost the same as keratosistik odontogenic tumors. However, amelioblastomas show more bone expansion and rarely show areas with high density.
Subtype
There are three major clinical subtypes of ameloblastoma: unicystic, multicystic, peripheral. Peripheral subtypes make up 2% of all ameloblastomas. Of all ameloblastomas in younger patients, unicystic amyloblastoma represents 6% of cases. The fourth subtype, which is malignant, has been considered by several oncology specialists; however, this tumor form is rare and may be merely a manifestation of one of the three major subtypes. Ameloblastoma also occurs in long bones, and other variants are craniopharyngioma (Rathke's pouch tumor, pituitary ameloblastoma).
Treatment
While chemotherapy, radiation therapy, curettage and liquid nitrogen have been effective in some cases of ameloblastoma, surgical resection or enucleation remains the most definitive treatment for this condition. In a detailed study of 345 patients, chemotherapy and radiation therapy appeared to be contraindicated for the treatment of ameloblastoma. Thus, surgery is the most common treatment of this tumor. Due to the invasive nature of growth, normal tissue excision near the tumor edge is often necessary. Some people equate this disease with basal cell carcinoma (skin cancer) in its tendency to spread to adjacent bones and sometimes soft tissues without metastasis. Although it is rarely not a cancer that actually invades adjacent tissues, ameloblastoma is suspected to spread to adjacent areas of the jawbone via the marrow space. Thus, a clear wide surgical margin of the disease is required for a good prognosis. It's very similar to cancer surgical treatments. Often, treatment requires excision of the entire jaw.
Radiation is not effective in many cases of ameloblastoma. There are also reports of induced sarcomas resulting from the use of radiation to treat ameloblastoma. Chemotherapy is also often ineffective. However, there is some controversy about this and some indications that some of the ameloblastoma may be more responsive to radiation previously thought.
Molecular biology
There is evidence that suppressing the metalloproteinase-2 matrix may inhibit local invasion of ameloblastoma, however, this is shown only in vitro. There are also some studies that show that <5> ? 1 integrins may participate in the local invasion of ameloblastoma.
A recent study found a high-frequency BRAF V600E mutation (15 of 24 samples, 63%) in solid/multicystic ameloblastoma. These data suggest drugs targeting mutant BRAF as a potential new therapy for ameloblastoma.
Repetition
Recurrence is common, although recurrence rates for block resection are followed by lower bone grafts than enucleation and curettage. Follicular variations appear to appear more than plexiform variants. Unicystic tumors recur less often than "non-unicystic" tumors. Continuous follow-up checks are essential for managing ameloblastoma. Follow-up should occur periodically for at least 10 years. Follow-up is important, because 50% of all recurrences occur within 5 years postoperatively. Recurrence in bone graft (after genuine tumor resection) does occur, but is less common. Breeding on bone graft is suspected as the cause of recurrence. The recurrence in this case appears to come from soft tissue, especially the adjacent periosteum. Recurrences have been reported to occur 36 years after treatment.
To reduce the possibility of recurrence in the grafted bone, careful operation with attention to adjacent soft tissues is required.
Epidemiology
The annual incidence rate per million for ameloblastoma was 1.96, 1.20, 0.18 and 0.44 for black men, black women, white men and white women respectively. Ameloblastomas account for about one percent of all oral tumors and about 18% of odontogenic tumors. Men and women tend to be equally affected, although women tend to be 4 years younger than men when tumors first appear and tumors appear larger in women.
See also
- Ameloblastic fibroma
- Bone transplant
- Epithelial cells rest on Malassez
- List of skin conditions
- Matrix Metalloproteinase-2
- Tooth development and Odontogenesis
References
External links
directory
- Radiologists and Patients MedPix Image Database
Source of the article : Wikipedia
0 Comments