Correspondence: Wing Cdr Muhammad Azhar Qureshi, Classified Surgeon, PAF Hospital, Faisal - Karachi.

 Ameloblastoma accounts for one percent of all oral tumours. The mandible is affected in about 80 % of cases, four times more frequently than the maxilla. Rarely it can occur simultaneously in mandible and maxilla1 and even maxilla, skull and groins successively on both sides [2]. Rarely they can pose diagnostic difficulties when they metastasise in kidneys, myocardium, lungs and in long bones as pathological fractures. Both sexes are affected equally. Although the tumour can occur at any age and has been described in the literature in patients as young as 21 months, most patients present in the third or fourth decade of life with the average age being 27 years. The remaining twenty percent occur in the maxilla with the maxillary tuberosity being the most common site.

Histologically, the ameloblastoma is a neoplasm of odontogenic epithelium with a fibrous background typically arising from tissue resembling the embryonic enamel organ (e.g., ameloblasts). The tumour consists of palisading columnar epithelial cells in the periphery of ameloblastic layer. The nuclei are polarized. There is mature connective tissue in stroma and loosely arranged stellate reticulum inside islands. There is no capsule. These bone tumours are histologically benign but locally destructive, typified by extensive invasion of cancellous bone and occasional cortical disruption with soft tissue extension. An enormous number of histologic variants of ameloblastoma have been described: follicular, pigmented, acanthomatous, plexiform, granular cell, stellate, basaloid, ameloblastic fibroma, and adenoameloblastoma.  The histologic pattern of these tumours, however, does not reliably predict their clinical course or serve as a guide to therapeutic decision making. Morphologically, ameloblastomas are classified into four groups; unicystic, solid or multicystic, peripheral, and malignant. Unicystic ameloblastomas are less aggressive than solid ameloblastomas and there is an intraluminal or an intramural proliferation of the cystic lining. Multicystic ameloblastoma has a poorer prognosis than the unicystic lesion due to excessive local infiltration. The peripheral ameloblastoma is the soft tissue version of ameloblastoma. It occurs in the alveolar mucosa and can involve underlying bone secondarily. The malignant ameloblastoma is again rare and it can metastasise to lungs [3], kidneys [4], myocardium [5] and to the long bones [6]. These four subtypes of ameloblastoma are dependent on ameloblastin gene (AMBN), which produce ameloblastin protein in organic matrix of enamel [7]. The matrix metalloproteinases (MMPs) is considered to be an important factor in the local invasiveness of this tumour [8] while Parathyroid Hormone Releasing Protein (PTHrP) plays a significant role in local bone resorption and destructive behaviour. It has significant therapeutic implications, particularly through PTHrP-blocking treatment modalities [9].

Fig. 1:     Segmental mandibulectomy showing extent of mandibular excision.     Fig. 2:     Closure of skin flap with a drain in position.

An ameloblastoma is an epithelial tumour similar to a basal cell carcinoma histologically. Therefore, some investigators contend that their radio sensitivities must also be similar. However, radiation therapy is rarely used as a primary treatment. Instead it is used in conjunction with surgery in the management of selected patients with recurrence. Surgery should be followed by radiotherapy in following instances. (1) Mandibular recurrences when the first surgical treatment was adequate, (2) for all recurrences and (3) when soft tissue involvement or positive surgical margins are present after a wide resection. Palliative irradiation has a role in inoperable cases but the role of chemotherapy is not yet established. There have also been reports of sarcomas induced when treating ameloblastomas with radiation.