'Combined ameloblastoma and odontogenic keratocyst' or 'keratinising ameloblastoma'

Papilliferous Keratoameloblastoma: Systematic review

Papilliferous keratoameloblastoma (PKA) is a rare entity, and not much is known about its clinicodemographic features or biological nature. This review aimed to provide clarity regarding the characterisation of the demographic, clinical, radiological and histopathological features of PKA. Case reports of PKA were identified through a systematic search across multiple databases. The search yielded a total of 10 cases, half of which were of Indian origin. All the cases invariably occurred in the mandibular posterior region and involved the right side; only one case primarily involved the left side of the mandible. PKA should be considered a variant of the conventional ameloblastoma that is towards the more aggressive end of the spectrum. It tends to occur in older individuals (in their fifth decade or older), with a marked propensity to occur in the right mandibular posterior region. Surgical resection with diligent follow-up is warranted in the treatment of PKA.

Keratoameloblastoma: A Report of Seven New Cases and Review of Literature

BACKGROUND

Keratoameloblastoma (KA) is an uncommon and controversial variant of ameloblastoma exhibiting central keratinisation. Due to their rarity, there is limited information in the literature on their clinical, radiologic and histologic features. This study adds seven additional cases of KA to the literature, and reviews the current published literature on this rare entity.

METHODS

KAs were retrospectively reviewed over a 20-year period from three Oral and Maxillofacial Pathology Laboratories. Included cases were examined and the diagnosis confirmed under conventional microscopy. Immunohistochemistry with the use of a monoclonal antibody against calretinin was performed on included cases. The clinical, radiologic and histologic features of the seven new cases of KA were analysed and compared to existing cases in the literature.

RESULTS

KAs presented at a mean age of 40 years with a nearly equal gender distribution and a mandibular predilection (65%). The majority (92%) of cases presented with localised swelling with associated pain in 32% of cases. Mixed density or internal calcifications were noted in 40% of cases. All tumours presented with bony expansion, with cortical destruction noted in 62% of cases. Histologically, all tumours consisted of solid and cystic follicles with surface parakeratinisation and lamellated accumulations of central keratin. In areas the cystic follicles had an epithelial lining suggestive of an OKC. There were focal luminal areas of loosely arranged polygonal cells reminiscent of the stellate reticulum. The basal cells consisted of columnar cells with evidence of palisading and prominent subnuclear vacuolisation. Of the cases treated via tumour resection, 27% presented with tumour recurrence.

CONCLUSION

This case series reports seven additional cases of KA, taking the total to 26 reported cases. The identification of subtle histologic features, including focal stellate reticulum-like central areas, subnuclear vacuolisation and lamellated-type central keratinisation, are key in diagnosing KA. The radiologic features will often indicate signs of aggressiveness such as cortical destruction, differentiating KA from OKC. All cases were completely negative for calretinin IHC, limiting its use in distinguishing KA from OKC. Further large series are needed to expand the current understanding of this rare variant of ameloblastoma.

Should the solid variant of odontogenic keratocyst and keratoameloblastoma be classified as the same entity? A clinicopathological analysis of nine cases and a review of the literature

The solid variant of odontogenic keratocyst (SOKC) is an extremely rare odontogenic lesion, which remains poorly defined even in the 2017 World Health Organization odontogenic tumour classification. It is difficult to distinguish between SOKC and so called keratoameloblastoma (KAB), both rare lesions that have similarities in clinical, histological and biological characteristics. Here, we report clinicopathological data and results of molecular analysis of nine cases with a literature review. First, they were compared to previously reported cases of SOKC and/or KAB, and many overlaps were found in clinical and pathological characteristics. Second, we performed PCR analysis for BRAF V600E mutation. Although ameloblastoma-like epithelia were often encountered, none exhibited BRAF V600E mutation, which has been reported to occur frequently in ameloblastomas but not in odontogenic keratocysts (OKCs). One of two cases of SOKC in the present series from which fresh frozen tissue specimens were available was found to harbour PTCH1 mutations, indicating that these were more likely to be a subtype of OKC. Moreover, we also examined the differences between SOKC and primary intraosseous carcinoma (PIOC) with regard to the expression of cytokeratins (pan-CK, CK5/6, CK7, CK8/18, CK10, CK14 and CK19), p53 and Ki-67. The proportions of p53-and Ki-67-positive cells were significantly higher in PIOC than in SOKC. These findings suggest that immunostaining for p53 and Ki-67 would be useful to differentiate between SOKC and PIOC. We also conducted a review of SOKC and KAB cases reported in the English language literature.

Synchronous occurrence of multiple distinct jaw lesions in Simpson-Golabi-Behmel Syndrome: A case report

Simpson-Golabi-Behmel Syndrome (SGBS) is an X-linked overgrowth syndrome characterized by pre- and post-natal overgrowth, typical facial appearance and multiple visceral, skeletal, and neurological anomalies. There is only few information in the current literature, on clinical and particularly dentofacial findings due to recent identification of the syndrome and its clinical overlap with other overgrowth syndromes. The aim of this case report is to present dentofacial findings in a 16-year-old boy who had been diagnosed with SGBS. Following comprehensive clinical, radiographic and histopathological examinations, six pathologically distinct lesions including odontogenic keratocyst, ameloblastoma, lateral periodontal cyst, dentigerous cyst and mucous retention cyst in both mandible and maxilla were identified. The clinical report is followed by a discussion aimed to clarify unique features of this condition and how practitioners should consider similar cases.

Peripheral keratoameloblastoma: A novel case report

Keratoameloblastoma is an exceptionally rare subtype of ameloblastoma that has been reported <20 times previously in the literature. All present as intraosseous lesions. We report an unusual case of keratoameloblastoma localized in the palate without involving palatal bone, thus presenting as a peripheral lesion. To the best knowledge of the authors, no case of peripheral keratoameloblastoma has been reported in the English literature till now, probably rendering this case to be the first one. Therefore, the purpose of this article is to present a rare and the first case of peripheral keratoameloblastoma with histopathological features of this tumor.

Keratoameloblastoma of the mandible

INTRODUCTION

Keratoameloblastoma is an extremely rare odontogenic tumor, as only 18 cases have been reported in the literature.

CASE REPORT

The authors report a case of keratoameloblastoma in a 32-year-old woman and review the literature concerning the clinical features, radiological appearance, histopathological findings and treatment options.

DISCUSSION

Keratoameloblastoma is a rare tumor observed more frequently in males (sex ratio: 3:1) characterized by extensive keratin production in odontogenic islets and fibrous stroma.

Keratoameloblastoma or Kerato-odontoameloblastoma: report of its soft tissue recurrence with literature review

Keratoameloblastoma (KA) is a rare histological variant of the ameloblastoma with extensive keratin production within the odontogenic islands as well as in the fibrous stroma. Pindborg first reported it in 1970, since then only 18 cases have been reported in the literature. We report a soft tissue recurrence of KA, involving right posterior region of the lower jaw in a 27-year-old female.

Simultaneous occurrence of keratocystic odontogenic tumor and ameloblastoma in the mandible: A case report

Keratocystic odontogenic tumors (KCOTs) and ameloblastomas are benign odontogenic tumors that primarily occur in the molar region of the mandible. However, it is uncommon for these tumors to arise simultaneously in a patient's jaw. The present study reported the diagnostic process and features of a rare case of the simultaneous occurrence of KCOT and ameloblastoma in the mandible of a 45-year-old male. Image-based diagnosis was challenging due to several conditions, including the intactness of the teeth and bone cortex as well as the sizes and locations of the lesions. Based on radiographic evidence, the patient was initially misdiagnosed and underwent a biopsy for a radicular cyst and a simple bone cyst prior to the correct diagnoses of KCOT and ameloblastoma, respectively. In addition, the present study discussed the diagnostic process of the present case and reviewed previous literature regarding the simultaneous occurrence of benign tumors of the jaw.

A rare case of hybrid odontogenic tumor: Calcifying epithelial odontogenic tumor combined with ameloblastoma

A hybrid odontogenic tumor comprising two distinct lesions is extremely rare. Nevertheless, such tumors have been reported in the literature for academic and research interest. However, it is still obscure whether they behave as a new entity or they solely present separate histopathologic patterns. Here, we present a true hybrid neoplasm of combined ameloblastoma and calcifying epithelial odontogenic tumor showing intermixed histopathologic patterns of both the tumors.

Keratoameloblastoma a rare entity: a case report

Ameloblastoma is the second most common odontogenic tumour of oral cavity; which has several different histological variants such as follicular, plexiform, acanthomatous, granular cell, desmoplastic, basal cell, clear cell, hemangiomatous, mucous cell differentiation and keratoameloblastoma. It is common in posterior mandible and has high male predilection in the ratio of 3:1. This report presents a case of keratoameloblastoma in 65-year-old female patient in the anterior mandible region with literature review on clinical features, histopathological findings, radiological appearance and treatment options.

Collision lesion of mandible--coexistence of keratocystic odontogenic tumor with central giant cell granuloma: a rare case report

AIM AND BACKGROUND

An odontogenic keratocyst (OKC) or keratocystic odontogenic tumor (KCOT) and giant cell granuloma (GCG) in the jaws are common lesions which have been studied extensively in detail over the years. However, a lesion showing features of both is exceptionally rare and is reported only twice in the literature till date.

CASE DESCRIPTION

A rare case of OKC in mandible showing foci of GCG like areas is reported in a 29 years old male patient.

CONCLUSION

It seems to be a collision lesion, though the possibility of KCOT showing a reactive response to form giant cells or it being a rare variant cannot be totally ruled out.

CLINICAL SIGNIFICANCE

This entity requires aggressive treatment since biological behavior of this unique lesion is difficult to predict unless more of such lesions are reported and followed up in future.

Notch signaling and ghost cell fate in the calcifying cystic odontogenic tumor

Notch signaling is an evolutionarily conserved mechanism that enables adjacent cells to adopt different fates. Ghost cells (GCs) are anucleate cells with homogeneous pale eosinophilic cytoplasm and very pale to clear central areas (previous nucleus sites). Although GCs are present in a variety of odontogenic lesions notably the calcifying cystic odontogenic tumor (GCOT), their nature and process of formation remains elusive. The aim of this study was to investigate the role of Notch signaling in the cell fate specification of GCs in CCOT. Immunohistochemical staining for four Notch receptors (Notch1, Notch2, Notch3 and Notch4) and three ligands (Jagged1, Jagged2 and Delta1) was performed on archival tissues of five CCOT cases. Level of positivity was quantified as negative (0), mild (+), moderate (2+) and strong (3+). Results revealed that GCs demonstrated overexpression for Notch1 and Jagged1 suggesting that Notch1Jagged1 signaling might serve as the main transduction mechanism in cell fate decision for GCs in CCOT. Protein localizations were largely membranous and/or cytoplasmic. Mineralized GCs also stained positive implicating that the calcification process might be associated with upregulation of these molecules. The other Notch receptors and ligands were weak to absent in GCs and tumoral epithelium. Stromal endothelium and fibroblasts were stained variably positive.

An unsuspected ameloblastoma in the subpontic region of the mandible with consideration of pathogenesis from the radiographic course

The purpose of this report is to document a case of unsuspected ameloblastoma involving the right man dibular subpontic region in a 38-year-old Cambodian female patient. This lesion was purportedly preceded by multiple radiolucencies which were diagnosed as radi cular cysts and treated a few times in the past years by enucleation followed by endodontic therapy of the affected teeth. Bridgework restoration of the partially edentulous area was performed. This case report de monstrates radiographic changes that occurred in the periods before and after the diagnosis of amelo blas to ma. The case may represent an example of radicular cysts and ameloblastoma occurring as a collision phenomenon, or the ameloblastoma may have arisen as a result of neoplastic transformation of the lining epi thelium in an inflammatory odontogenic epithelial cyst.

Keratoameloblastoma: a tumor sui generis or a chimera?

The term keratoameloblastoma has been used to describe a histologically heterogeneous group of ameloblastoma variants which have in common the formation of keratin by the ameloblastomatous epithelium. The English language literature contains reports of only 12 cases of keratoameloblastoma, of which 4 cases exhibited a papilliferous component. We report a unique tumor that we believe falls within the broad histopathologic spectrum of keratoameloblastoma. We review the key clinical and histopathologic features of the previously reported cases of keratoameloblastoma and present an additional case that presented as an expansile, radiolucent lesion with internal opacification between the roots of teeth in the left anterior maxillary alveolar ridge of a 45-year-old white male. There is wide variation in the histopathologic appearance of cases reported under the appellation keratoameloblastoma. Our case exhibited a histopathologic feature shared by only 2 of the previously reported cases, notably islands and anastomosing cords of epithelium forming lamellated, pacinian-like stacks of parakeratin that extruded into the collagenous tumor stroma without eliciting a foreign body response. Due to the small number of reported cases, we are unable to accurately assess whether the biologic behavior of keratoameloblastoma differs from other histologic types of ameloblastoma.

Synchronous ameloblastoma and orthokeratinized odontogenic cyst of the mandible

The simultaneous occurrence of ameloblastomas with odontogenic cysts or other non-odontogenic lesions have already been described as combined lesions. However, we are unaware of any report in the English literature of simultaneous occurrence of ameloblastoma and orthokeratinized odontogenic cyst (OOC) occurring as completely distinct lesions. This report shows a case of synchronous ameloblastoma and OOC, located on posterior regions of the mandible, but in distinct sides.

Metachronous ameloblastomas in the maxilla and mandible: report of a case

Ameloblastoma is a locally aggressive tumour of odontogenic origin, with an unknown aetiology. Metachronous ameloblastoma in the maxilla and the mandible is rare. In this report, a case of a 63 year-old man is described with a solid ameloblastoma in the posterior part of the upper jaw. After surgical treatment, the patient returned 8 years later with a similar lesion in the anterior lower jaw. Both ameloblastomas were of the solid type but differed in their histological patterns. No evidence of recurrence was found in either of the surgical sites for the last 4 years.

Effect of preservation of the inferior and posterior borders on recurrence of ameloblastomas of the mandible

OBJECTIVE

The purpose of this study was to evaluate the experience and results of using a rational radical conservative approach in the surgical treatment of mandibular ameloblastomas.

STUDY DESIGN

A retrospective analysis of every patient with an ameloblastoma of the mandible treated in the Department of Oral Medicine and Oral Surgery at the Jordan University of Science and Technology between 1989 and 1999 was conducted. All were operated on by the author, who used a uniform surgical protocol in every case. All soft tissues in contact or overlying the lesion and a wide margin of cancellous bone related to the tumor were destroyed. The compact bone comprising the lower border of the mandible and the posterior border of the ascending ramus together with the nutrient periosteum attached to them were preserved, thus maintaining the continuity of the mandible and the facial contours. When teeth, soft tissues, or both were involved, they were destroyed. All patients were reviewed annually for a follow-up period of 3 to 10 years (mean, 6.5 years) by the same clinician.

RESULTS

All ameloblastomas were located in the mandible; 21 were in the angle/molar region and the ascending ramus, and 2 cases were in the anterior region. There was no clinical or radiographic evidence of recurrence observed during the follow-up period.

CONCLUSION

Ameloblastoma has a high rate of local recurrence if it is not adequately removed. The findings of this study to date suggest that the technique of rational radical conservative resection may have a place in the treatment of ameloblastoma of the mandible and is worthy of further trial.

Keratoameloblastoma of the maxilla. A case report and review of the literature

The keratoameloblastoma is a rare histologic variant of the ameloblastoma. Review of the English language literature revealed five case reports of keratoameloblastoma. We report the sixth case of this tumor. The tumor developed in the right posterior maxilla of a 26-year-old African-American man and demonstrated aggressive clinical behavior, analogous to conventional ameloblastoma. The initial biopsy specimen showed extensive cyst formation, which histologically resembled odontogenic keratocyst. However, the lining epithelium varied in thickness and there was separation and edema between the basal cells and the rest of the epithelium. The basal cells were strongly adherent to the underlying stroma unlike the basal layer of the odontogenic keratocyst, where cleavage often occurs in this area. Additionally, although the basal cells were palisaded and demonstrated nuclear polarization in areas, they were cuboidal rather than columnar. The excision specimen revealed more of a solid ameloblastic component in addition to the cystic component seen on the initial biopsy. Nevertheless, it is possible that the ameloblastoma had developed in an odontogenic keratocyst. Alternatively, it can be postulated that the keratoameloblastoma consists of both cystic and solid components, the former being analogous to the cysts of the conventional ameloblastoma.