Ameloblastic Carcinoma of the Mandible: A Case Report
Corresponding author: Dr. Mohamed Amine ALLOUANE, Department of ENT, 20 Août hospital, Ibn Rochd University Hospital, Casablanca, Morocco, E-mail: firstname.lastname@example.org
Malignant odontogenic tumours are rare and represent ap- proximately 1% of all oral malignancies. 
Ameloblastic Carcinoma (AC) is an uncommon malignant ep- ithelial odontogenic tumour of jaw, with characteristic histo- logic features and behavior. Clinically, it is aggressive in nature with extensive local bone’s destruction that has retained the features of ameloblastic differentiation. Also,it exhibits cyto- logical features of malignancy. Majority of the cases arise de- novo (primary). Only few cases arise from a pre-existing ame- loblastoma (secondary). 
Ameloblastic carcinoma secondary type is extremely rare. It arises through carcinomatous de-differentiation of a pre-exist- ing ameloblastoma or odontogenic cyst.it is typically followed by repeated treatments and recurrences of the benign precur- sor neoplasm. 
In the updated World Health Organisation (WHO) classifica- tion of Head and Neck tumors (2005), ameloblastic carcinoma
is categorized into three main subtypes: primary type, second- ary type (dedifferentiated) intraosseous and secondary type (dedifferentiated) peripheral. 
Imprecisions regarding histopathological diagnosis has brought difficulties for researchers indelineating reliable in- formation on ameloblastic carcinoma’s pathogenesis, predi- lections, treatment and outcomes. 
Surgical resection of the primary tumor with wide margins is the mainstay treatment of ameloblastic carcinoma.  Neck dissection is only indicated in cases with positive lymph node involvement. Recent reports also mention the benefits of ra- diotherapy after initial surgical intervention, especially with the use of megavoltage therapy. 
We present a rare case of mandibular ameloblastic carcinoma wich is a secondary type in a previously treated ameloblasto- ma.
A male patient aged 70 years who is under high blood pressure treatement, operated twice for ameloblastoma at the same site. He has been presented to the ENT-HNS Departement 20 Aout 1953 University Hospital for chief complaint of swelling on the right side of face that was present since six months [Fig-1]. The swelling was associated with pain, difficulty in mastication and mouth opening.
Figure 1: Swelling on the right side of face.
We find in the clinical examination a firm mass taken the majority of the right hemi mandible, which is measuring 11 cm and beginning 2 cm behind the mandibular symphysis extending backwards to the ramus at its lower 1/3. The skin has a normal appearance that is non-inflammatory and mobile relatively to the deep plane. The examination of the oral cavity finds a burgeoning and sessile mass with an irregular surface.
Orthopantomogram (OPG) showed the presence of multilocular radiolucency extending from the canine to ramus of the mandi- ble. It was associated with displacement of tooth with erosion of bone including inferior border of the mandible.
The MRI showed a lobulated, expansile and lytic lesion, which involved the body, and the ramus. It was measured 9.1×8.2×7.8 cm in size with perforation of the cortical plates [Fig-2].
Based on clinical and radiographic features, the lesion was provisionally diagnosed as ameloblastoma and we did not find evidence of distant metastasis.
The patient was operated twice but the evolution was marked by recidivism.
Figure 2: MRI: lobulated, expansile and lytic lesion, which involved the body, and the ramus.
Right hemimandibulectomy was performed with free surgical margins without neck dissection. The reconstruction was done with pectoralis major flap and a maxi plaque. The excised lesion was sent for histopathological analysis.
Histopathological result finds bone tissue with an ameloblastic carcinomatous proliferation of cribriform masses, which are composed of monomorphic cells surrounding an eosinophilic substance. Infiltration of the nerve filaments was noted as well as a cortical effraction and presence of emboli.
Ameloblastic carcinoma is an extremely rare odontogenic malig- nant tumor with a reserved prognosis. It is a lesion with histologic behavior that dictates more aggressive surgical approach than that of a simple ameloblastoma.  The mean age for occurrence is
30.5 years, male: female ratio is 1.5:1, and 80% are located in the mandible posterior region. 
In 2005, the revision of the World Health Organization’s (WHO) histological classification of odontogenic tumors classified amelo- blastic tumors as several entities : ameloblastoma, metastasiz- ing ameloblastoma, primary ameloblastic carcinoma and second- ary ameloblastic carcinoma. Most of the ameloblastic carcinomas are primary type and occur de novo, whereas the secondary type is less reported in the Literature .
The clinical symptoms of ameloblastic carcinoma are more aggressive than conventional ameloblastoma, with swelling, pain, rapid growth, trismus, expansion of the jaws, and frequently perforation of the cortex.  The clinical manifestations and the therapeutic management of the two types primary and secondary are the same.
Radiographic appearance of ameloblastic carcinoma is con- sistent with the one of ameloblastoma except for occasional presence of some focal radiopacities, reflecting dystrophic cal- cification.  The imaging is not specific and has only an orien- tation value and a locoregional extension.
The diagnosis of ameloblastic carcinoma is based on research into the histology of malignancy criteria that is associated with the tumors criteria of the ameloblastic family.
Histologically, ameloblastic carcinoma does not show uniform proliferation, and has pleomorphic and hyperchromatic cells arranged in the form of sheets and chords with reversed po- larity.  there are no distinguishing characters between the two types . Primary and secondary ameloblastic carcino- mas are differentiated more by the clinical history than the histology.
It is important to differentiate between secondary ameloblas- tic carcinoma and malignant or metastatic ameloblastoma that its histology is devoid of malignant criteria and which has secondary sites in particular pulmonary. Many authors have shown that metastasizing ameloblastomas are histologically indistinguishable from classic ameloblastomas.
Differential diagnosis included odontogenic keratocyst, squa- mous cell carcinoma and ameloblastoma. The squamous odon- togenic tumor may also be mistaken for ameloblastic carcino- ma, being composed of islands of squamous epithelium that lack stellate reticulum like zones, peripheral palisading, micro- cystic changes and dystrophic calcifications.
Whether ameloblastoma may transform biologically and his- tologically from a classic ameloblastoma to a malignant lesion is controversial. The high rate of recurrence maybe due to the mode of growth and surgical mismanagement rather that any inherent malignant properties and metastases are “exceeding- ly rare.” 
There is no consensus regarding the treatment of ameloblastic carcinomas, and surgery with healthy surgical margins offers the best prognosis .
Wide local excision is the treatment of choice as most inves- tigators have recommended, . Regional lymph node dis- section should be performed selectively where in the regional lymph node was palpable. The efficacy of adjuvant radiation or chemotherapy as a postsurgical treatment is not clear and seems to have a limited value.  Data regarding chemother- apy is sparse. Lanham treated a patient with doxorubicin, cis- platin, cyclophosphamide, dacarbazine, and 5 FU; but, the tu- mor failed to respond.  Yoon et al. have reported distant metastasis as early as 4 months and as late as 47 months after surgery. 
However, more recent reports suggest radiotherapy may ben- efit postoperative patients who have locally recurred or those with residual disease after resection. This may be in part owing to improvements in treatment techniques, as older series often used orthovoltage irradiation and radium needles instead of megavoltage irradiation. 
In our case, the patient has not lymph nodes, and the treatment was based only on surgery with wide margins, without radio- therapy. The evolution was favorable without recurrence
Figure 3: Post-operative result.
Figure 4: Post-operative result
Ameloblastoma shows a variety of histologic and biologic be- havior ranging from benign to frank malignancy. When a case is diagnosed as ameloblastic carcinoma, assessment of nodal metastasis and evidence of distant metastasis should be eval- uated. Treatment of ameloblastic carcinoma is wide surgical resection and if evidence of nodal metastasis is present, neck dissection should also be considered.
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