|Year : 2014 | Volume
| Issue : 4 | Page : 283-286
Desmoplastic hybrid ameloblastoma presenting as a fibrous epulis
LR Kumaraswamy Naik1, Pushparaja Shetty2, Padmaraj Hegde3
1 Department of Oral Pathology, SJM Dental College and Hospital, Chitradurga, India
2 Department of Oral Pathology, AB Shetty Memorial Institute of Dental Sciences, Deralakatte, Mangalore, Karnataka, India
3 Department of Oral and Maxillofacial Surgery and Craniofacial Reconstruction, AB Shetty Memorial Institute of Dental Sciences, Deralakatte, Mangalore, Karnataka, India
|Date of Web Publication||20-Nov-2014|
L R Kumaraswamy Naik
Department of Oral Pathology, SJM Dental College and Hospital, Chitradurga, Karnataka
Desmoplastic ameloblastoma (DA) is a rare variant of ameloblastoma with specific clinical, imaging, and histological features. Histologically, it is characterized by extensive stromal desmoplasia with small compressed nests and strands of odontogenic epithelium. The purpose of this article is to present a case of central DA that showed unusual clinical presentation of a classic solid/multicystic ameloblastoma occurring as a peripheral lesion in the form of gingival epulis, arising from extraction site and showed histopathological feature of a hybrid variant.
Keywords: Basaloid ameloblastoma, desmoplastic ameloblastoma, gingival epulis, granular cell ameloblastoma, hybrid variant
|How to cite this article:|
Kumaraswamy Naik L R, Shetty P, Hegde P. Desmoplastic hybrid ameloblastoma presenting as a fibrous epulis. SRM J Res Dent Sci 2014;5:283-6
|How to cite this URL:|
Kumaraswamy Naik L R, Shetty P, Hegde P. Desmoplastic hybrid ameloblastoma presenting as a fibrous epulis. SRM J Res Dent Sci [serial online] 2014 [cited 2019 Oct 17];5:283-6. Available from: http://www.srmjrds.in/text.asp?2014/5/4/283/145170
| Introduction|| |
Desmoplastic ameloblastoma (DA) was first reported by Eversole et al. and was recently included in the World Health Organization's (WHO) classification of head and neck tumors (WHO-2003) as a separate variant of ameloblastoma, with specific clinical, imaging, and histological features. , Among all other types of ameloblastomas, DA is uncommon and occur with the incidence of 4-13%.  DA occurs more frequently in fourth and fifth decades of life, and presents no predilection toward either gender. DA does tend to affect the anterior-premolar region of the jaws as a central lesion and in gingiva as a peripheral lesion.  Radiographically 50% of DA show an image suggesting of a benign fibro-osseous lesion.  Histologically, it is characterized by extensive stromal desmoplasia with small compressed nests and strands of odontogenic epithelium.  DA with areas of classical follicular or plexiform ameloblastomas has been described as hybrid lesion.  It is an extremely unusual lesion and was first described in detail by Waldron and el-Mofty.  The purpose of this article is to present a case of central DA that showed unusual clinical presentation of a classic solid ameloblastoma occurring as a peripheral lesion in the form of a gingival epulis and a hybrid histopathological features.
| Case report|| |
A 30-year-old female patient reported to AB Shetty Memorial Institute of Dental Sciences, Mangalore with a complaint of swelling in the left lower teeth region since 4 months. Initially, the swelling was small and gradually increased to reach the present size. No secondary changes were seen with the swelling. Medical history was unremarkable. Patient had undergone extraction of tooth in the same region 5 months back, for a complaint of loosening. There was no previous radiograph or records available. On intraoral examination, oral hygiene status was good. There was a solitary well defined swelling seen on the left attached buccal gingiva and alveolar bone, measuring about 3 cm × 2 cm and extending from the mesial aspect of the lower left first premolar to the distal aspect of lower left second molar. Lower left first molar was missing. The mucosa overlying the swelling was erythematous [Figure 1]. The swelling was nontender and firm in consistency. There was buccal cortical plate expansion with obliteration of buccal sulcus. Lower left second premolar was vital, and lower left second molar was carious and nonvital. Conventional radiographs revealed a well demarcated radiolucency measuring about 2 cm × 1.5 cm in the alveolus of left mandible with missing left lower first molar [Figure 2]. There was root divergence in relation to second premolar and second molar. Root resorption was not seen. Incisional biopsy was received for histopathological examination, and it revealed islands of odontogenic epithelium in dense mature collagenous stroma. The stroma was of less cellularity with small blood capillaries. Epithelial islands were small, compressed and were in the form of cords and strands with rounded, irregular and with angular budding extensions suggesting of DA [Figure 3]. Some areas showed arrangement of these islands in the form of follicles with peripheral palisading columnar cells with hyperchromatic reverse polarized nucleus. The central areas showed stellate reticulum like cells with microcyst formation suggesting of follicular ameloblastoma [Figure 4]. Diagnosis of DA, a hybrid variant was made. Segmental resection of mandible from left lower canine tooth to left lower third molar was performed under general anesthesia. Lower border of mandible was preserved. Excisional biopsy showed similar features of hybrid DA, in addition it also revealed presence of basaloid cell variant [Figure 5] and granular cell variant [Figure 6] of ameloblastoma. Diagnosis of hybrid DA was confirmed. Patient is currently showing no signs of recurrence since 10 years.
|Figure 2: Pantamograph showing a well demarcated radiolucency in the alveolus of left mandible with missing 36|
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|Figure 3: Photomicrograph showing odontogenic epithelial islands with rounded irregular angular budding extensions in the background of fibrous connective tissue with marked desmoplasia (H and E stained section with original magnification, ×10)|
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|Figure 4: Photomicrograph showing tumor islands in the form of follicular ameloblastoma (H and E stained section with original magnification, ×10)|
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|Figure 5: Photomicrograph showing tumor islands in the form of basaloid variant of ameloblastoma (H and E stained section with original magnification, ×10)|
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|Figure 6: Photomicrograph showing tumor islands in the form of granular cell variant of ameloblastoma (H and E stained section with original magnification, ×10)|
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| Discussion|| |
Since the first description of DA by Eversole et al. a total of 115 cases have been reported. , Hybrid DA is extremely rare lesion and till now around 17 cases are reported in English literature. They tend to affect Asian population.  Present case occurred in a 30-year-old patient although the previous reports suggest occurrence in older age groups. Site affected was of mandibular molar area similar to classic solid/multicystic ameloblastoma though previous reports suggest that DA frequently occur in anterior to premolar region. , Clinical presentation of the present case was confusing with that of a peripheral reactive gingival lesion. Peripheral ameloblastomas usually occur as fibrous nodules and simulate reactive lesions. They are usually slow growing and little or no bone erosion of the underlying bone seen due to pressure rather than invasion.  We believed the lesion to be a central one and popped out from the extraction site due to the presence of cortical plate expansion and root divergence. Root resorption is a common finding in DA, but was not seen in our case.  Though the oral hygiene was good, reason for extraction of molar tooth according to patient was due to loosening of the tooth. And it is one of the features of ameloblastoma.  Though radiologically 50% of DA shows an image suggesting of a benign fibro-osseous lesion, in the present case the lesion showed complete radiolucency, and this is a feature of solid multicystic ameloblastoma.  Histologic appearance of DA is characteristic and differs from solid multicystic ameloblastoma in the nature of collagenous fibrous stroma. Odontogenic islands in these tumors are irregular, appear to be compressed or squeezed by the stromal tissue, giving rise to the stretched-out tail-like appearance.  Ashman et al. reported a case of DA which demonstrated granular cell transformation in some of the tumor cells along with areas of follicular and plexiform ameloblastoma, while Hirota et al. reported a case of DA depicting associated follicular, plexiform, acanthomatous and basaloid changes.  Present case showed typical features of DA along with features of follicular, basal cell, and granular cell ameloblastomas all occurring in the same lesion. Whether the hybrid lesion represents an alteration in a preexisting DA or whether desmoplastic areas represent some form of alteration of stroma and epithelial morphology is a matter of debate. Angadi et al. believe that areas of conventional ameloblastoma may, in fact, be a histopathological spectrum of DA due to specific clinical and radiological pattern.  However, the present case is an exception that it occurred in the posterior part of mandible and showed clear radiolucency similar to conventional ameloblastoma. Immunohistochemical studies by Santos et al. postulate that extracellular matrix molecules like tenascin, demonstrable in the stroma of follicular part of hybrid lesions and type I collagen and fibronectin seen throughout the lesion may participate in tumoral modulation of hybrid DA.  However, this conclusion cannot be drawn on a single case study. More number of cases of hybrid DA and DA and other variants of ameloblastomas are to be studied immunohistochemically to draw a conclusion regarding desmoplasia. Present case did not show any areas of calcification though areas of osteogenesis and cementogenesis are reported to occur in DA.  The majority of DA cases reported in the literature have been treated by resection, most likely due to ill-defined borders, thus suggesting an infiltrative process and an aggressive biological behavior.  Recurrence rate of DA was reported up to 15.9% in literature. Among 17 cases of hybrid DA only two cases showed recurrence. One among them was treated with curettage and no information about the treatment in other case.  We believe DA and hybrid DA should be treated by complete surgical resection similar to solid multicystic ameloblastoma and should be followed up for long term.
| Conclusion|| |
Present case showed the importance of a thorough examination of clinical and radiological findings and necessity for histopathological diagnosis though the lesion looks much benign clinically in the form of an epulis. When the lesion is associated with the previous history of extraction due to mobility of the tooth, it indicates the aggressive behavior. Though DA is considered as a distinct entity, present case report showed clinical and radiographical feature of a conventional ameloblastoma. More number of cases of DA and hybrid DA are to be studied in order to draw a proper conclusion regarding the desmoplasia in a conventional ameloblastoma and DA showing other variants of ameloblastoma. DA and hybrid DA should be treated by complete surgical resection similar to solid ameloblastoma and are to be followed up for long term.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]