MASQUERADE OF A CYST : UNICYSTIC AMELOBLASTOMA

Dr. Jochima Eudora Cota 1 , Dr. Anita Spadigam 2 and Dr. Anita Dhupar 3 . 1. MDS (Oral Pathology), Goa Dental College and Hospital. 2. Dean, Head and Professor, Department of Oral and Maxillofacial Pathology, Goa Dental College and Hospital. 3. Professor, Department of Oral and Maxillofacial Pathology, Goa Dental College and Hospital. ...................................................................................................................... Manuscript Info Abstract ......................... ........................................................................ Manuscript History

Unicystic ameloblastomas are a rare type of Ameloblastoma that clinically, radiographically present as a cyst but on histological examination show a typical ameloblastomatous epithelium. The concept of this tumour was first introduced by Robinson and Martinez in 1977. This is a case report of a 10 year old child presenting with a mandibular swelling and a peculiar radiological finding, highlighting the importance of histological examination in the diagnosis of unicystic ameloblastoma. A brief review of the pathogenesis of unicystic ameloblastoma and the various histological patterns that play a role in the diagnosis of a unicystic ameloblastoma and formulating the definitive treatment approaches for such lesions has been discussed.

Case Report:-
A 10 year old boy presented with a slowly growing swelling on the right side of the mandible since one year. No history of trauma, pain, difficulty in swallowing or occlusion was reported. On physical examination face appeared asymmetrical with a diffuse swelling over the right side of the face. The skin was not attached to the underlying swelling and the inferior margin of mandible was continuous. Intraorally, a single, smooth swelling over the right mandibular alveolar ridge extending from 83 to 46 antero-posteriorly and causing expansion of the buccal cortical plate obliterating the buccal vestibule and slight expansion of the lingual cortical plate was noted. Overlying mucosa appeared blanched. Carious root piece of 83 was evident. On palpation, the swelling was bony hard, smooth and non-tender. No neck nodes were palpable. Systemic examination was normal. A provisional diagnosis of Keratocystic odontogenic tumour/OKC was agreed upon, with a differential diagnosis of dentigerous cyst, ameloblastoma and radicular cyst. An orthopantomogram (OPG) was done, which showed large unilocular radiolucent lesion in the right side of mandible associated with impacted 43, 44 and 45, 84 appeared to be within the cystic cavity. Mandibular true occlusal showed an expansion of the buccal cortical plate.

ISSN: 2320-5407
Int. J. Adv. Res. 5(6), 444-447 445 On histological examination, a cystic lining with basal cells that appeared columnar to cuboidal with hyperchromatic nuclei showing reverse polarity (ameloblast like cells) were noted. Luminal proliferation was seen. The suprabasilar cells were loosely arranged resembling stellate reticulum like cells being consistent with a unicystic ameloblastoma.

Discussion:-
Unicystic ameloblastoma usually occurs in younger age group and more than 90% are located in the mandible. (Figueiredo NR et al., 2015) Clinically it presents as a dentigerous type (associated with an impacted tooth) and a non-dentigerous type (not associated with teeth). The first two groups of lesions may be treated successfully by enucleation or curettage; it has been suggested that recurrence following conservative surgery is more likely to occur in the third group and that these lesions should therefore be treated by radical resection, as for a solid or multicystic ameloblastoma (Garcia NG et al., 2016).
Marx and Stern classified the lesion as ameloblastoma in situ (developing in and limited to the epithelial lining of a cyst), micro-invasive ameloblastoma (arising from the epithelial lining and proliferating into the connective tissue layer of the cyst) and invasive ameloblastoma (arising from the epithelial lining and proliferation through the complete thickness of the connective tissue layer of a cyst). They suggested that ameloblastoma in situ and microinvasive ameloblastoma should be treated with enucleation. Yet, invasive ameloblastoma should be treated with resection (Garcia NG et al., 2016). The present case did not show any evidence of mural proliferation. Hence, considering the age of the patient and the histopathological features, a conservative mode of treatment in the form of enucleation was advised.

Conclusion:-
It is of utmost importance to correlate histopathologic findings with clinical and radiographic features to arrive at a correct definitive diagnosis. The Pathologist should examine the tissue sections carefully in an attempt to determine whether ameloblastoma has penetrated the wall of the cyst or not so that the complications can be minimized.