AN UNUSUAL CASE OF EXTRA FOLLICULAR ADENOMATOID ODONTOGENIC TUMOR: A CASE REPORT.

Dr. Asha R Iyengar 1 , Dr. Seema Patil 2 ,Dr. Meghna Gohain 3 , Dr. Subash BV 4 , Dr. Rahamath Fatimah 5 and Dr. Ritika Agarwal 6 . 1. Professor, Department of Oral Medicine and Radiology, DA Pandu Memorial RV Dental College, Bangalore, Karnataka, India. 2. Professor and Head of Department, Department of Oral Medicine and Radiology, DA Pandu Memorial RV Dental College, Bangalore, Karnataka, India. 3. Postgraduate, Department of Oral Medicine and Radiology, DA Pandu Memorial RV Dental College, Bangalore, Karnataka, India. 4. Reader, Department of Oral Medicine and Radiology, DA Pandu Memorial RV Dental College, Bangalore, Karnataka, India. 5. Postgraduate, Department of Oral Medicine and Radiology, DA Pandu Memorial RV Dental College, Bangalore, Karnataka, India. 6. Post graduate, Department of Oral Medicine and Radiology, DA Pandu Memorial RV Dental College, Bangalore, Karnataka, India. ...................................................................................................................... Manuscript Info Abstract ......................... ........................................................................ Manuscript History

A provisional diagnosis of infected radicular cyst was given. Calcifying odontogenic cyst, Traumatic bone cyst Ossifying fibroma and Calcifying epithelial odontogenic tumor were considered in the differential diagnosis as these lesions commonly occur in females, in the mandibular premolar region and present as a bony hard swelling.
On electric pulp testing, 43 showed delayed response and 44,45 responded normally.
Orthopantomograph revealed a circular, well-defined, mixed radiolucent radio-opaque lesion in the inter-radicular region of 43 and 44 approximately measuring 2x2 cm (Fig3). Superio-inferiorly, it extended 3mm beneath the alveolar crest upto the apex of 43 and 44. Medio-laterally, it extended from distal aspect of root of 44 to mesial aspect of root of 43. Internal structure revealed specks of calcification. Displacement of roots of 43 and 44 were noted.
CBCT revealed a well-defined radiolucent lesion with clearly defined radiopaque margins in the inter-radicular region of 43 and 44 measuring approximately 11.54mm x 12.40mm x 13.52mm (Fig4a). Expansion of buccal and lingual cortical bone plates was noted (Fig4b). Root divergence of 43 and 44 was noted with no root resorption. Radiographic DD of Calcifying cystic odontogenic tumor, Adenomatoid odontogenic tumour, Calcifying epithelial odontogenic tumour and Ossifying fibroma were considered. However, root resorption is common in CCOT, CEOT and ossifying fibroma and appearance of calcifications varies in each.
Following the investigations, extraction of 43 and 44 was done. Enucleation of the lesion was performed under local anesthesia (fig5). Suturing was done and primary hemostasis was achieved.
On macroscopic examination, the tissue specimen was well circumscribed and spherical in shape measuring about 1.3cm attached to a small bony spicule . The color appeared pinkish-grey. The mass was soft to fluctuant in consistency.
The Hematoxylin and eosin stained sections revealed a thick fibrous capsule, a nodular proliferation of cuboidal, columnar, spindle and polygonal cells. The cells were arranged in nodules, strands and plexiform patterns. Eosinophilic droplets were seen between these cells. Cystic spaces lined by flattened cells, few duct-like structures and few rosettes were also observed. Eosinophilic material and calcifications of varying sizes were present. Areas resembling calcifying epithelial odontogenic tumour (containing polyhedral squamous cells with prominent intercellular bridges) were also seen.

Discussion:-
The occurrence of extra-follicular type is quite rare with a prevalence of 26.9% compared to follicular type which accounts for 70.8% of all AOTs 2 . The pathogenesis of AOT is not clear and a number of hypotheses have been proposed. Theoretically, it is said to arise from the enamel organ, the epithelial lining of the dentigerous cyst, epithelial rests of Malassez of the deciduous or permanent tooth, or remnants of the dental lamina and may show an ameloblastic phenotype 4 . However, Philipsen et al also argued that all AOT variants show identical histological features and therefore it points towards a common origin from the dental lamina or its remains. 5 A Pubmed search of extra-follicular AOT revealed 35 case reports of extra-follicular AOT till date out of which detailed case history was available only in 13 cases (13+22). (Included in Table 1.) Of these 13 case reports, 8 cases were seen in women indicating a slight female predilection. It was mostly reported in young adolescent, however, 4 cases were seen in middle aged. The number of cases occurring in maxilla was 7 and the rest in mandible suggesting no definite preference of maxilla or mandible. Out of 13 cases, 7 cases were seen in the anterior region and aggressive forms were seen in 4 cases. Most of them presented as a painless hard swelling of the involved jaw bone. From the above findings, we can infer that there has been a change in the trends with regard to clinical presentation in AOT and variations have been observed from what has been believed conventionally. The present case also seemed to show a few variations from previous literature as it occurred in an older female (55 years) in the anterior mandible and was associated with pain.
Radiographically, extrafollicular AOTs can be divided into 4 subdivisions based on its location and relationship with 1163 adjacent teeth viz., E1 -No relation to tooth structure either erupted or unerupted, E2-Intra-radicular adjacent roots diverge apically due to tumor expansion, E3-Superimposed on the root apex and E4-superimposed on the mid-root level. All 13 cases presented as circumscribed radiolucent area with a well-defined corticated or sclerotic border. Internal structure showed fine calcifications, flocculent pattern and patchy calcifications in 3 cases. Expansion of cortical plate was seen in 4 cases. The size of the intraosseous lesions varied from 0.8cm to 4cm. Root resorption was seen in 6 cases and root deviation in all the cases.Majority of them belonged to E2 variant and 1 case belonged to E3 variant.The present case belonged to the E2 variant with typical radiographic features.
Histologically, all the variants of AOT are seen to have the same histological features. It may present as a solid mass or as cystic spaces which is well-encapsulated. Duct-like structures are seen lined by a single row of columnar epithelial cells giving a rosette-like pattern. Spindle-shaped or polygonal cells are seen forming sheets and whorled masses in a scant connective tissue stroma. The lumen may be empty or filled with amorphous eosinophilic material. Dystrophic calcification is usually encountered in most cases.
In the present case, along with the above described histopathological features typical of AOT (fig6a), a few areas of the tissue sample contained polyhedral squamous cells mimicking a CEOT (fig6b). Review of literature supports the presence of CEOT like feature in few cases of AOT. 19 In the last few years, several studies have reported immunohistologic properties of AOT. The classical AOT phenotype is characterized by a cytokeratin (CK) profile similar to follicular cyst and/or oral or gingival epithelium based on positive staining with CK5, CK17, and CK19. Recently, Crivelini, et al. detected the expression of CK14 in AOT and concluded that this probably indicate its origin in the reduced dental epithelium. 8 The surgical management of this tumor is usually enucleation along with the associated impacted tooth and simple curettage. Conservative treatment is adequate because the tumor is not locally invasive, is well encapsulated, and is separated easily from the bone. The recurrence rate is as low as 0.2% 9 . In addition, the use of lyophilized bone and guided tissue regeneration are recommended in large osseous cavities 7 . The prognosis is usually excellent in majority of the cases.

Conclusion:-
It may be inferred from the present case that AOT does not always occur in a narrow age range and in restrictive sites and can show variations in its presentations. Hence, it is suggested that AOTs must be considered in differential diagnosis of mixed radiolucent radio-opaque lesions occurring in older age group, anterior mandible, the absence of an impacted tooth.