The growth characteristics of multilocular ameloblastomas. A histological investigation with some inferences with regard to operative procedures

Defining giant mandibular ameloblastomas - Is a separate clinical sub-entity warranted?

Context:

The term giant mandibular ameloblastoma (GMAs) while being in popular usage in the medical literature remains largely equivocal. Although a few authors have in the past attempted to ascribe definite criteria to this entity, these are by and large arbitrary and without any benefit in decision-making or contributing to its management.

Aims:

The aim of this study is to propose a set of objective criteria for GMAs that can be clinically correlated and thereby aid in the management of this entity.

Patients and Methods:

Of a total of 16 patients with ameloblastoma of the mandible presenting at our institute from August 2012 to September 2016, 11 patients were identified as having GMAs as per the criteria proposed.

Results:

The defects in the mandible following segmental resection ranged from 7 to 11.5 cm in length (mean: 9.3 cm). No clinical or radiological evidence of tumour recurrence was found during a mean follow-up period of 10.7 months (range: 2–28 months).

Conclusions:

Defining GMA based on objective inclusion and exclusion criteria allows segregation of these lesions, thereby helping to remove ambiguity, simplify decision-making and facilitate communication among treating reconstructive surgeons. Inclusion criteria include: (i) The segmental bone defect following resection with a minimum 1 cm margin of healthy bone should exceed 6 cm (ii) The segmental bone defect should involve the central mandibular segment.

Marsupialization of mandibular cystic ameloblastoma: Retrospective study of 7 years

BACKGROUND

This retrospective study investigated the reduction rate and speed of shrinkage after marsupialization in mandibular cystic ameloblastoma and clarified whether marsupialization is appropriate for unicystic ameloblastoma and multicystic ameloblastoma.

METHODS

Sixty-three patients with mandibular cystic ameloblastoma were initially treated with marsupialization. Premarsupialization and postmarsupialization panoramic radiographs were reviewed for reduction rate and speed of shrinkage, and then were evaluated with age, sex, tumor location, and tumor type.

RESULTS

The overall recurrence rate was 4.5% (2/44). The average reduction rate after marsupialization was 65.6%. No significant difference was found between unicystic ameloblastoma and multicystic ameloblastoma in reduction rate. The speed of shrinkage of unicystic ameloblastoma was significantly faster than that of multicystic ameloblastoma (P < .05). Similarly, patients with multicystic ameloblastoma had longer marsupialization periods than those with unicystic ameloblastoma (P < .05).

CONCLUSION

Marsupialization is effective in reducing tumor size for both unicystic ameloblastoma and multicystic ameloblastoma. Marsupialization plus second-stage curettage is recommended as the primary treatment for mandibular cystic ameloblastoma.

Reconstruction of the bony chin using sagittal split osteotomies of the remaining mandible - A new technique for a special indication: Case report

There are several indications for resecting the bony chin, such as squamous cell carcinoma, sarcoma, or benign tumors of the jaw such as ameloblastoma. Several techniques for reconstruction of the bony chin, such as the use of metal plates and also revascularized free bone grafts of the iliac crest, fibula, or scapula, are common. In the case of poor vascular supply, however, alternative techniques may be necessary. In this report, a new technique is described using pedicled bone flaps from both sagittally split mandibular stumps following chin resection. These flaps were pedicled on the mylohyoid muscles and advanced to restore the continuity of the mandible. An advantage of this procedure was minimization of the soft tissue defect, making repair easier. Morbidity of the resection and reconstruction was thus reduced, and recovery of the patient was very quick.

"Evaluation of safety margin" in ameloblastoma of the mandible by surgical, radiological, and histopathological methods: An evidence-based study

OBJECTIVE

The purpose of this study is to elicit the amount of safety margin necessary around the ameloblastic lesion in view of preventing further recurrence.

MATERIALS AND METHODS

The study consisted of 25 cases of mandibular ameloblastoma. Diagnosis was based on clinical and radiological analysis and confirmed by histopathological report. An incisional biopsy was done preoperatively to confirm the diagnosis. Segmental resection was planned for all the cases. After the resection, postoperative panoramic radiograph of the specimen was taken followed by histopathological examination of its margin to detect tumor cell infiltration.

RESULTS AND CONCLUSION

In all our cases, the ameloblastoma was infiltrating in nature. A follow-up period of 10 years showed neither recurrence nor implant failure. In our study, we conclude our safe margin for infiltrating variant of ameloblastoma based on histopathological report of the resected specimen.

Plexiform ameloblastoma

The ameloblastoma is a benign but aggressive neoplasm of odontogenic origin. However, no enamel or hard tissue is formed by the tumor cells. Ameloblastomas are infamous for their invasive growth and their tendency to recur. Robinson (1937) as a benign tumor that is ‘usually unicentric, nonfunctional, intermittent in growth, anatomically benign and clinically persistent.’ They may occur at any age, even though nearly half of the tumors do occur between the ages of 20 and 40 years. This is the most common neoplasm affecting the jaws, yet only accounts for 1% of all tumors of the maxilla and mandible and 11% of all odontogenic tumors.

This report presents a case of ameloblastoma involving entire ramus and part of body of mandible with resorption of the mesial and distal root apices of second molar and distal root of mandibular first molar. The lesion extending till the base of mandible surrounding the crown of the unerupted third molar resembling the dentigerous cyst. This was surgically resected followed by harvesting the contralateral sixth costochondral rib graft.

How to cite this article: Celur S, Babu KS. Plexiform Ameloblastoma. Int J Clin Pediatr Dent 2012;5(1):78-83.

Complete oral rehabilitation of a postresection ameloblastoma patient: a clinical case report

Conventional ameloblastomas are rare, benign, epithelial odontogenic tumors that tend to grow slowly in the mandible or maxilla, but are locally invasive and can be highly destructive of the surrounding dental anatomy. Aggressive resection is the most effective method of eliminating the tumors, but treatment can further contribute to patient deformity and malfunction. Ameloblastomas also have a high rate of recurrence, which significantly diminishes 8 years after resection, but still requires vigilant clinical monitoring. This case report describes the complete oral rehabilitation of a postresection ameloblastoma patient with a mandibular reconstruction plate and partial edentulism. An autogenous graft was taken from the patient's iliac crest, shaped to fit the defect, and attached with bone screws. After graft incorporation, dental implants were successfully placed into the augmented ridge and restored with a fixed partial denture. There was no evidence of tumor recurrence during the 10 months of treatment or 8 years of subsequent clinical monitoring.

Lesions of the jaws

The jaws differ in various aspects from all other bones in the skeleton. Embryologically, they are for the major part derived from migrating cells of the cranial neural crest, the so-called ectomesenchyme, and not merely from mesoderm, and they contain teeth. This latter point, especially, results in the presence of lesions that are not found in other bones, a broad variety of odontogenic cysts and tumours. They will be the major topic of this review. Other lesions, not strictly odontogenic but also mainly confined to the jaw bones, are giant cell lesions, fibro-osseous lesions, and the melanotic neuro-ectodermal tumour of infancy. They also will be included in this overview.

[Ameloblastomas]

OBJECTIVES

The aim of this work was to report on the clinical, radiological and histological characteristics of ameloblastomas concerning bone structures of the face, rare but not exceptional tumours, and to communicate our experience of their treatment.

MATERIAL AND METHODS

The authors reexamined six recent cases of patients presenting with ameloblastoma at the centre Antoine Lacassagne in Nice. The diagnostic context, the treatment and the development of the disease are given in detail, emphasizing the frequency of local relapse of this histologically benign condition.

RESULTS

The study of these cases confirmed the benefit of surgical treatment of ameloblastoma. The frequency of local relapse in the cases of close resection, leaving in place micro-foci, justifies enlarged intervention, which is often bone destructive.

CONCLUSION

When the continuity of the bone is interrupted, in particular at the level of the mandible, and if the general condition of the patient permits, repair is preferable. In this situation, the procedure of choice is micro-anastomosis of the fibula.

A case of recurrent ameloblastoma developing in an autogenous iliac bone graft 20 years after the initial treatment

A case of recurrent ameloblastoma developing in an autogenous iliac bone graft 20 years after radical resection of primary mandibular ameloblastoma is presented. This case showed extensive bony resorption extending throughout the auto-grafted bone. Seeding to the graft bone was suspected as a cause of the recurrence in the iliac bone graft because wide destruction of the graft bone was observed without any prior signs and symptoms of intraoral mucosa. Consequently, extensive resection of bone as well as adjacent soft tissue was performed. Persistent follow-up examination is essential for management of ameloblastoma.

Ameloblastoma in the Hong Kong Chinese. Part 2: systematic review and radiological presentation

OBJECTIVES

The aim of this part of the study was to determine the radiological presentation on conventional radiographs of central ameloblastomas in the Hong Kong Chinese and compare them with other reported series by a systematic review (SR).

METHODS

The study had two elements, that of a complete series of all ameloblastomas presenting at a major Chinese maxillofacial surgical unit and a SR. The files of the Department of Oral and Maxillofacial Surgery of the University of Hong Kong between 1989 and 2000 were reviewed for ameloblastoma cases. The relevant literature was identified by electronic databases, review of citation lists and handsearching of key journals. The principal selection criterion was that the study should represent a complete collection of cases.

RESULTS

Only 13 reports gave any radiological details. The present study of the Hong Kong Chinese contained 61 cases. With the exception of radiodensity and shape of radiolucency, the majority of the 13 other reports did not record the other radiological features that could be important in the diagnosis. The present study agreed with the synthesis of the 13 reports with regards to complete radiolucency and cortication of ameloblastomas, but disagreed with regards to other important features. The present study had a significantly higher proportion of unilocular lesions, better marginal definition, and more frequent perforation of the cortex and buccolingual expansion. Nine of the ten maxillary lesions straddled both anterior and posterior sextants with four crossing the midline, whereas only 13 of the 51 mandibular cases affected both sextants, of which eight crossed the midline. The unicystic form, which was most prevalent, appeared significantly more frequently as unilocular radiolucencies in comparison with the non-unicystic forms. The frequencies of unicystic forms and unilocular presentations were significantly greater in the young. The lesions in the young were significantly sited solely in the posterior sextant. The lower border of the mandible was reached and affected by ameloblastoma in 36 cases in the present report. It was displaced and thinned in 15 cases whereas in just five it was at least partially undisplaced with the lesion expanding down past it either buccally or lingually to it. The unicystic form was significantly more associated with root resorption, tooth displacement and crowns of unerupted teeth.

CONCLUSIONS

Radiologically, ameloblastomas in the Hong Kong Chinese differ significantly with regards to many features. This can be in part explained by the higher proportion of the unicystic form.

Recurrence of multicystic ameloblastoma in soft tissue

Ameloblastoma is characteristically considered to be a benign but locally aggressive and infiltrative odontogenic tumour with a high recurrence rate. Most recurrences of the solid or multicystic ameloblastoma occurred at the edges of the initial tumour or at the bony cavity left after the excision of a tumour. A case of an isolated soft tissue recurrence of ameloblastoma of the mandible in a 58-year-old man is presented. The report illustrates the need to take into consideration the adjacent soft tissue in cases of tumour with cortical bone perforation during surgical treatment. This is especially important in an environment where patients are not likely to attend follow-up review for a long period. It also demonstrates the ability of intraosseous ameloblastoma to grow in soft tissues.

Segmental mandibulectomy and immediate free fibula osteoseptocutaneous flap reconstruction with endosteal implants: an ideal treatment method for mandibular ameloblastoma

Thirteen patients with large ameloblastomas of the mandible underwent segmental mandibulectomy and immediate reconstruction, with simultaneous placement of osseointegrated implants. All patients received palatal mucosal grafts around the dental implants 6 to 10 months after surgical treatment and received implant-supported prostheses another 1 to 2 months later. There were five female and eight male patients, with a mean age of 32 years (range, 17 to 50 years). The mean length of the mandibular defect was 8.8 cm (range, 5 to 13 cm). All free fibula flap procedures were successful, with no reexplorations or partial flap losses. There was no clinical or radiographic evidence of failure during the osseointegration process for any implant. With functional occlusal loading, the marginal bone loss around the implants was less than 1.5 mm in a mean follow-up period of 40 months (range, 18 to 70 months). There were no recurrences during that time. The technique described allows improved access to the bone at the time of reconstruction, immediate assessment of alveolar ridge relationships, and accurate fixation of the implant-fibula construct. The advantages of this procedure include a reduced risk of recurrence with segmental resection, reliable mandibular reconstruction, and reduction of the number of surgical procedures, allowing full oral rehabilitation in a shorter time. It is concluded that segmental mandibulectomy and immediate vascularized fibula osteoseptocutaneous flap reconstruction, with simultaneous placement of osseointegrated implants, represent an ideal treatment method for large ameloblastomas of the mandible.

Comparison of long-term results between different approaches to ameloblastoma

OBJECTIVE

The long-term results of different surgical approaches to ameloblastoma were compared to develop a more rational surgical approach to this tumor.

STUDY DESIGN

Seventy-eight primary ameloblastomas, including 27 unicystic, 21 multicystic, and 30 solid-type tumors, were examined in this study. The methods of treatment consisted of radical surgery (ie, resection-both segmental and marginal) and conservative treatments (ie, marsupialization alone, marsupialization followed by enucleation with sufficient bone curettage if necessary, and enucleation with bone curettage). The effect of marsupialization on recurrence data after a follow-up period of at least 5 years was evaluated with respect to clinical type and histologic pattern.

RESULTS

Marsupialization was performed in 31 cystic ameloblastomas before surgery, and the effective rate of marsupialization was 74.2%. Recurrence was observed in 7.1% (3/42) after radical surgery and in 33.3% (12/36) in conservative treatments. Relatively higher tendencies of recurrence were observed in the multicystic type and follicular and/or plexiform pattern tumors.

CONCLUSIONS

Conservative treatments including marsupialization and enucleation followed by sufficient bone curettage were thought to be useful, reducing the need for jaw resection. This result extends the indications for conservative treatment of ameloblastoma.

Growth characteristics of ameloblastoma involving the inferior alveolar nerve: a clinical and histopathologic study

OBJECTIVE

Growth characteristics of ameloblastomas involving the inferior alveolar nerve were examined to determine the most appropriate surgical management of the nerve at the time of the surgical procedure.

STUDY DESIGN

Clinical and histopathologic examinations were performed on 22 resected mandibles in which the inferior alveolar nerve was lying adjacent to, or contained within, the tumor.

RESULTS

Patterns of tumor involvement of the nerve bundle were evaluated with respect to the presence of bone (11 patients) or connective tissue wall (7 patients) between the tumor and the nerve bundle, and tumor infiltration of perineural connective tissue (4 patients). Neither invasion into the nerve sheath nor invasion into the nerve itself by the ameloblastoma was detected. Tumor infiltration of the tissue surrounding the nerve was identified for the multicystic and solid types but not for the unicystic type. Presence of bone or connective tissue wall between the tumor and the nerve bundle was dominant in the unicystic and plexiform ameloblastomas, whereas tumor infiltration of the perineural tissue was frequently observed in ameloblastomas with the follicular pattern.

CONCLUSION

The preservation of the inferior alveolar nerve may be possible in the management of the unicystic type of ameloblastoma. However, a more radical approach is necessary for treatment of multicystic or solid tumors, especially those exhibiting a follicular pattern.

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.

Desmoplastic variant of ameloblastoma in Chinese patients

Desmoplastic ameloblastoma is a rare tumour, and we know of only 43 previously reported cases. We report seven Chinese patients (five men and two women) with the desmoplastic variant of ameloblastoma, which makes up 9% of all ameloblastomas diagnosed during the years 1981-1995. The age ranged from 18 to 68 years (mean 43). Five of the tumours were in the maxilla and two were in the mandible. Five of them were situated anteriorly, the remaining two cases involving both anterior and posterior maxilla. The features of the 42 cases previously reported were reviewed and were compared with those in the present study. Our results differ in that we found a male predominance, wider age range and more tumours in the maxilla. Histologically, this variant of ameloblastoma is characterized by abundant collagenous stroma. Because the epithelial clusters may show prominent squamous metaplasia or may be compressed into thin strands in most areas, the appearance may mimic a squamous odontogenic tumour or odontogenic fibroma. The behaviour of this variant of ameloblastoma is likely to be the same as that of the classic ameloblastoma.

Management of solid ameloblastoma of the jaws with liquid nitrogen spray cryosurgery

OBJECTIVE

This study evaluated the results of the use of curettage followed by liquid nitrogen spray cryosurgery in a number of solid or multicystic ameloblastomas of the jaws and the postoperative complications related to this treatment modality.

STUDY DESIGN

Thirty-six patients with solid ameloblastoma of the jaws were treated with curettage followed by cryosurgery. The cryotherapy consisted of hand instrumented curettage of the bone lesion followed by three freezing cycles, of 1 minute each, of the remaining bone cavity with liquid nitrogen spray. Postoperative complications were evaluated clinically and radiographically.

RESULTS

Local recurrence occurred in 11 (30.6%) patients. Excepting local recurrence, postoperative complications were frequent but not severe: wound dehiscence (5.5%), paraesthesia (5.5%), infection (5.5%), and pathologic fracture (11.1%).

CONCLUSION

Management of solid or multicystic ameloblastomas of the jaws with curettage followed by cryosurgery may decrease the local recurrence rate and also to reduce the initial indication of resection with continuity defect.

Marsupialization of cystic ameloblastoma: a clinical and histopathologic study of the growth characteristics before and after marsupialization

PURPOSE

This study evaluated the effectiveness of marsupialization for the treatment of cystic ameloblastoma.

MATERIALS AND METHODS

Clinical and histologic examination of 24 cystic ameloblastomas were performed before and after marsupialization.

RESULTS

Clinically and radiographically, the effect of marsupialization was evaluated as extremely effective (five cases), effective (11 cases), and noneffective (eight cases). Marsupialization was most effective in teenaged patients. In three cases, the tumor disappeared macroscopically, and further surgery was not done. Histologically, the growth characteristics of the tumor were classified into expansive and invasive types. Cytologic pattern was classified into three types according to the outer cell layer of the tumor parenchyme: cuboidal cell, columnar cell, and basal cell. Premarsupialization, the expansive pattern with the cuboidal cell type was dominant, whereas for postmarsupialization many cases that had been expansive changed to an invasive type showing columnar or basal cell types.

CONCLUSION

Marsupialization was found to be useful as a preliminary treatment of the cystic ameloblastoma. However, it must be borne in mind that following marsupialization the tumor still has a potential to infiltrate into the surrounding tissues.

Healing after removal of benign cysts and tumors of the jaws. A radiologic appraisal

A retrospective review of the radiographic findings after removal of benign jaw cysts (n = 31) and ameloblastomas (n = 24) was carried out. The radiographic features of the site margins and interior contents were classified into four categories. In most patients radiographic changes were detected between 1 and 4 months after removal of the lesion, and complete bone healing was found 4 months or more after surgery. Radiographic changes included "spiculed" or "trabecular" contents within the interior of the surgical site. The fourth month was found to be the optimum time for follow-up radiographic examination for the early detection of residual lesions. In nine (53%) of the patients who had ameloblastoma, recurrent lesions were noted within or at the periphery of the original surgical sites 6 to 10 years after the initial tumor removal.

Late loco-regional recurrences after radical resection for mandibular ameloblastoma

5 cases of mandibular ameloblastoma are described with multiple recurrences after a long period of time. 4 of them were primarily treated by radical resection. 1 was initially treated by enucleation and extensive resection was performed only after its recurrence. The invasive growth of the recurrent tumor into the soft tissues and the cranial base, necessitating extensive ablative and reconstructive surgery, reflects the potential aggressiveness of this tumor. It is therefore recommended, to plan an adequate resection in cases of multicystic ameloblastoma, which includes a margin of at least 1 cm, of apparently non-invaded bone. If the tumor has eroded through the cortical bone and invaded into the soft tissues, wider margins are necessary to eliminate possible tumor extensions that are left behind. Adequate follow-up on a regular basis should enable the clinician to detect early recurrence so as to avoid major surgery.