Ameloblastomas are locally aggressive jaw tumors with a high propensity for recurrence and are believed to arise from the remnants of odontogenic epithelium, lining of odontogenic cysts, and the basal layer of the overlying oral mucosa.1 Ameloblastomas can occur in either the maxilla or mandible at nearly any age, but most frequently are discovered as a painless expansion in the mandible of patients in their 20s-40s.2 The first detailed description of this lesion was by Falkson in 1879, but the term ‘ameloblastoma’ was coined by Churchill in 1933.3 Ameloblastoma represents approximately one per cent of oral tumours, It is the second most common odontogenic neoplasm accounting for 9% to 20% of all odontogenic tumors with 80 per cent of ameloblastomas occurring in the mandible4 and approximately 15-20% ameloblastomas originating in maxilla with just 2% arising anterior to the premolars. Ameloblastoma has a persistent and slow growth, spreading into marrow spaces with pseudopods without concomitant resorption of the trabecular bone. As a result, the margins of the tumour are not clearly evident radiographically or grossly during operation, and the lesion frequently recurs after inadequate surgical removal, showing a locally malignant pattern.5 Long term  follow-up is necessary because this lesion has been shown to recur 25 and 30 years following primary treatment.6, 7  According to the recent Classification of Odontogenic Tumors, by World Health Organization (WHO), four subtypes of benign ameloblastomas are recognized: the 1)solid/multicystic, 2) desmoplastic, 3) unicystic and the 4)extraosseous/peripheral type.8

A 40-year-old man presented to Norvic International Hospital Kathmandu Nepal, with a 3-month history of progressive left-sided nasal obstruction, with blood mixed nasal discharge and left sided facial swelling. He had no associated history of epistaxis, pain, or anosmia and was otherwise healthy, with no previous sinonasal disease. His oral examination revealed loose third premolar tooth. Nasal endoscopy showed exophytic polypoidal mass arising from left middle meatus extending till anterior border of inferior turbinate. A preoperative CT scan was performed showing left maxillary sinus and nasal cavity soft tissue mass associated with extensive bone destruction may be categorized with following differential diagnosis 1. Left maxillary sinus malignancy with extension all around with pansinusitis until proved otherwise 2. ?inverted papilloma left maxillary sinus with pansinusitis .DNS to right side with posterior destruction of septum. Osteomeatal complex are blocked.  (Figure 1, 2).The presence of unilateral involvement and bone erosion on CT raised suspicion for a neoplasm, and the mass was biopsied under local anaesthesia via endoscope. Anterior nasal packing was done. Hemostasis was achieved. On histologic examination, sections show well differentiated epithelium with minimal atypia comprising of nests, strands and cyst lining with peripheral palisaded columnar cells having dark stained basal nuclei and vacuolated cytoplasm, edematous spindled stellate reticulum-like areas are also noted features are suggestive of ameloblastoma left maxilla.(Figure 3).Immunohistochemistry of block shows ANTI P63 positive in all cells CK19 diffuse positive, CD56 positive in peripheral cells (Figure 4) and Calretinin positive in stellate reticulum like epithelial cells. Based on the clinicoradiologic and immunohistochemical findings, a diagnosis of left maxillary ameloblastoma was done. The patient was planned for lateral rhinotomy and partial maxillectomy. After rhinotomy incision was given and soft tissue dissected of cheek, mass was seen covered by periosteum. Anterior wall was totally destructed. Laterally maxillary bone was absent with buldging of buccal pad of fat. Medial wall was also destructed partially with visualization of nasal cavity and mass. Medial maxillectomy was done. Posterior wall and superior wall was totally intact with stripping of mucosa done. Floor of maxilla was destructed with intact   hard palate mucosa.

Figure 1: Axial cut left nasal and maxillary sinus mass with bony destruction.

Figure 2: Coronal cut left nasal and maxillary sinus mass with bony destruction.

Figure 3:Histopathology examination showing well differentiated epithelium with minimal atypia having dark stained basal nuclei and vacuolated cytoplasm edematous spindled stellate reticulum-like areas.

Figure 4: CD56 positive in Immunohistochemistry in peripheral cells.

It is generally accepted that only 20 per cent of ameloblastomas occur in the maxilla. Although some reports indicate an incidence as low as one per cent in the maxilla [9] and of those 47 per cent occur in the molar region, 15 per cent in the antrum and the floor of the nose, 9 per cent in the premolar areas, 9 per cent in the canine area and 2 per cent in the palate area. Since maxillary ameloblastoma has a predominantly painless and slow growth because of the lack of a thick cortical plate, the plentiful cancellous bone and the proximity of the maxilla to the nasal cavity, nasopharynx, paranasal sinuses, orbits and skull base, there is commonly a delay in the recognition of the maxillary ameloblastoma extending into these structures and this itself may provide useful diagnostic evidence.[10] In our case tumour was involving the floor , lateral wall, medial wall of maxillae. However the posterior wall and roof was intact. Ameloblastomas are epithelium-derived odontogenic tumors that typically are originated in jaw bones, primarily involving the mandible and less often the maxilla. The presence of ameloblastomas in sinonasal region is usually secondary to an extension of a tumor of gnathic origin into this area. Although hypothetical, it appears quite likely that this embryological approximation allows the sinonasal tract mucosa either to incorporate odontogenic epithelium or to acquire cells capable of odontogenesis during development. A number of modalities have been proposed in the treatment of ameloblastoma, like wide excision, curettage, enucleation, cryotherapy, cautery, laser usage, radiotherapy and chemotherapy.11 Good results have been obtained either with radical treatment [12, 13] or more conservative approaches [14] although enucleation and curettage have been reported as methods with the highest rate of recurrence. So, it appears that the best surgical method for the treatment of a maxillary ameloblastoma is a limited or wide excision of the tumour [15] with a [10-15] mm margin of normal bone if available. This may include resection of the alveolar ridge, hard palate and maxillary sinus and the lateral nasal wall. [16] Prognosis depends on extension of lesion rather than origin. Wide maxillectomy was the method of choice in this case. A long term follow up is necessary because this lesion has been shown to recur 25-30 years following primary treatment.

Although this slow-growing tumor is benign, it is locally aggressive and has a high rate of recurrence. Malignant transformation has also been reported.[17]   So long term follow up is necessary. In our case the patient had locally aggressive disease which was removed in total by lateral rhinotomy and partial maxillectomy. In the three year follow up period serial nasal endoscopy and CT scan was done and there is no recurrence yet.

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