Predominantly cystic central mucoepidermoid carcinoma developing from a previously diagnosed dentigerous cyst: case report and review of the literature

Assessment of MUC5AC and MUC2 Immunoexpression in Glandular Odontogenic Cysts, Dentigerous Cysts, and Mucoepidermoid Carcinomas

Glandular odontogenic cysts (GOCs) and dentigerous cysts may show mucous metaplasia. Central mucoepidermoid carcinoma is very rare and mostly associated with dental cysts. It is hypothesized that odontogenic cysts showing mucus differentiation in their lining, have a propensity to transform into MEC. The present study is the first attempt to explore the relationship between odontogenic cysts [GOCs and dentigerous cysts with mucus metaplasia (DCMM)] and MEC by evaluating immunoexpression of MUC5AC and MUC2. Immunoexpression of MUC5AC and MUC2 was evaluated semiquantitatively in GOCs (20 cases), DCMMs (20 cases), and MECs (20 cases). The percentage of positive cells, intensity, and localization of immunoexpression were assessed for each marker in all cases. Of GOCs, DCMMs, and MECs cases, 85%, 70%, and 80%, respectively, were immunopositive for MUC5AC. Strong cytoplasmic immunoreactivity for MUC5AC was noted, particularly in mucous cells present diffusely within MECs. However, the immunoreactivity was limited to the epithelial lining of GOCs and DCMMs. Most of the MECs (60%) showed more than 25% positivity for MUC5AC, followed by GOCs, and the least in DMMCs. Mild cytoplasmic and nuclear positivity of MUC2 was noted only in epithelial lining cells of 70% GOCs and 45% DCMMs. Whereas, 55% of MECs displayed moderate to strong cytoplasmic and membranous immunopositivity for MUC2 exclusively within mucous cells. As MECs showed strong MUC5AC immunoreactivity in mucous cells, immunoexpression of MUC5AC in odontogenic cysts with mucus cells can possibly explain the pathogenesis of MEC from cysts. However, the variable expression of MUC2 did not give any strong evidence regarding its role as a marker.

Central Mucoepidermoid Carcinoma Radiographically Mimicking an Odontogenic Lesion

Central mucoepidermoid carcinoma (CMEC) is a rare pathological entity with only a few case reports in the literature. The present case reported an uncommon occurrence of CMEC mimicking an odontogenic lesion in a young patient. A 17-year-old female patient sought dental care due to a slight swelling located in the posterior region of the mandible on the left side. Radiographic exams revealed an osteolytic lesion with defined limits in relation to proximity to the pericoronal follicle of tooth #38. The clinical and radiographic diagnostic hypothesis was an odontogenic lesion. Histological sections showed the presence of a neoplasm of glandular origin, not encapsulated, with a predominantly cystic growth pattern. The neoplasm consisted of mucous, intermediate, and squamous cells. In the immunohistochemical staining, the neoplastic cells were positive for cytokeratin 7. Mucous cells were positive for PAS with diastase digestion. The final diagnosis consisted of mucoepidermoid carcinoma. The tumor was removed surgically, and the patient has shown no signs of relapse nor recurrence. In conclusion, CMEC may mimic radiographic features of various pathologies, but despite its rarity, clinicians and oral radiologists should consider CMEC as a diagnostic hypothesis for jaw lesions.

Unicystic Mucoepidermoid Carcinoma: A Pitfall for Clinical and Pathologic Diagnosis

Unicystic mucoepidermoid carcinoma (UC-MEC) is a rare MEC variant, and its diagnosis is frequently problematic. This study is aimed at summarizing its clinicopathologic characteristics, treatment, and prognosis and proposing key points to avoid missed diagnosis and misdiagnosis in clinical and pathological conditions. This retrospective study included 30 UC-MEC cases, and the clinical findings were collected from the clinical medical records. Radiographic features, histologic behaviors, MAML2 rearrangement by fluorescence in situ hybridization (FISH), and follow-up data were analyzed. Moreover, glandular odontogenic cyst (GOC) and cytadenoma (CA) were used as controls. In the UC-MEC group, 19 patients were female (63%), and 11 were male (37%). The mean patient age was 39.5 (range, 7–72 years). The affected locations included the jaw (8 maxillary, 3 mandibular) and salivary glands (7 parotid, 11 palates, and 1 floor of the mouth). The chief complaint was swelling; the lesions were all cystic, among which 66.7% were well circumscribed and 33.3% poorly defined. Microscopic examination showed two UC-MEC histologic subtypes. Type A presented as a single cyst with mural thickening (8/30, 27%) lined predominantly by epidermoid cells with interspersed intermediate and mucinous cells, and type B (22/30, 73%) showed infiltrative tumor islands in the cystic wall or the surrounding tissue. FISH analysis suggested that approximately 66.7% of UC-MEC harbored a MAML2 rearrangement. During the median follow-up period of 42 months (range, 6–120 months), all type A patients and 68% of type B patients who underwent complete surgical resection lived without relapse. Seven cases with type B cancer that underwent curettage initially had local recurrence. Clinicians and pathologists hardly recognize UC-MEC owing to its cystic architecture. Specific epidermoid, mucous, and intermediate tumor cells, and MAML2 fusion testing, are essential to avoid potential diagnostic pitfalls. Prompting and completing resection surgery with negative margins would have a favorable prognosis.

Complete removal of dentigerous cysts with preservation of associated teeth as an alternative to marsupialization in children and preadolescents

The aim of this study is to evaluate the results of dentigerous cysts enucleation with preservation of cyst-associated teeth as a single procedure in a group of children and preadolescents. A retrospective case series of seven patients with 15 unerupted developing teeth associated with or adjacent to dentigerous cysts was conducted. Patients were treated using the uniform surgical protocol (cystectomy, preservation of cyst-associated teeth, without use of orthodontic traction, primary wound closure). The metric analysis of the cysts and unerupted teeth on CBCT and an evaluation of the state of involved teeth after the treatment was performed. The mean age of patients was 9.0 ± 2.1 years (range 5-12 years, median = 9 years). All teeth erupted spontaneously. No serious postoperative complications or recurrences of lesions were detected. The mean follow-up was 53.1 ± 15.7 months (range 25-71 months, median = 52 months). The cystectomy of dentigerous cysts with preservation of associated teeth may be considered an alternative to marsupialization in children and preadolescents.

The reliability of MAML2 gene rearrangement in discriminating between histologically similar glandular odontogenic cysts and intraosseous mucoepidermoid carcinomas

OBJECTIVE

MAML2 expression is proven in the majority of mucoepidermoid carcinomas (MECs) arising in salivary glands. MEC can also occur intraosseously (IMEC). Glandular odontogenic cyst (GOC) is an odontogenic cyst with histologic overlap with IMEC. This study aimed to determine the reliability of MAML2 in distinguishing IMEC cases from GOC cases.

STUDY DESIGN

An institutional review board-approved retrospective search of IMEC, GOC, and IMEC with prior history of GOC was performed within the archives of the University of Florida and the University of Alberta Oral Pathology Biopsy Services. Nine cases from 5 patients were selected. Break-apart fluorescent in situ hybridization analysis was performed on 7 cases for the presence of MAML2 rearrangement.

RESULTS

Four cases had negative MAML2 gene rearrangement, and 3 cases had positive MAML2 gene rearrangement.

CONCLUSIONS

Although it can be concluded that the 3 cases with positive translocation for MAML2 were IMECs, the same conclusion could not be drawn for the 4 cases with negative translocation. Whether the cases that were negative for translocation were GOCs with MEC-like islands or were MAML2-negative IMECs could not be ascertained. Therefore, MAML2 rearrangement is not always reliable in differentiating IMECs from GOCs with overlapping histology.

An unusual case of intraosseous mucoepidermoid carcinoma of the mandible: A case report and literature review

RATIONALE

Mucoepidermoid carcinoma (MEC) is the most common primary salivary gland malignancy. Ectopic MEC can occur in any part of the body, however, only 2% to 4% of MEC could be detected in the jaw, which is named intraosseous mucoepidermoid carcinoma (IMC). IMC is usually a low-grade carcinoma. Uni- or multilocular radiographic lesions should be differential diagnosed with ameloblastoma, odontogenic cysts, and glandular odontogenic cyst (GOC). Radical surgery may prefer for a favorable prognosis. Whereas IMC can recur long after the operation, a long-term follow-up system should be implemented. Owing to its rarity and controversial issues, we report a case report and review the literature to discuss its clinical features, treatments, radiological, and histological characteristics.

PATIENT CONCERNS

The patient presented with a 2-month history of mild pain in the lower left posterior jaw without history of surgery or trauma to the mandible.

DIAGNOSES

Routine postoperative pathology showed that the mass was consistent with a mandibular mucoepidermoid carcinoma.

INTERVENTION

Radical surgery and digital mandibular reconstruction were performed.

OUTCOME

Postoperative imaging showed that the height of the mandible and the symmetry of the mandible were satisfactory. The patient was also satisfied with her appearance. Follow-up has been established.

LESSONS

Effective surgical treatment allows patients to have a favorable prognosis. A long-term follow-up system should be practiced, because local recurrences and regional metastasis could happen even after decades.

Intraosseous mucoepidermoid carcinoma: Outcome review

OBJECTIVE

Identify the effect of patient characteristics, disease traits, and treatment modality on patient outcomes in the rare disease process of intraosseous mucoepidermoid carcinoma.

STUDY DESIGN

Retrospective review of institutional case records and literature.

METHODS

This study includes one case report, a literature review of the MEDLINE database from 1950 through June 2017 using keywords "intraosseous" and "mucoepidermoid," and a query of the University of California, Los Angeles, Department of Pathology database for all documented cases of intraosseous mucoepidermoid carcinoma of the head and neck.

RESULTS

Indicators of poorer prognosis were male gender (P = 0.0071) and higher histological grade (P = 0.0095). Lesion site, size, association with odontogenic cyst, and treatment type did not have a statistically significant correlation with patient outcomes. There also was no statistically significant correlation observed between treatment modality and recurrent or progressive disease when stratified by histological grade of the cancer.

CONCLUSION

This study identified male gender and high histological tumor grade as poor prognostic indicators; however, it did not reveal a statistically significant relationship between treatment modality and patient outcomes. Data regarding patient outcomes following treatment was limited due to loss to follow-up, suggesting that further investigation is required. Based on this review, decisions regarding treatment should be clinically guided and individually tailored to the patient's baseline health, disease severity, and the patient's treatment goals. A multi-disciplinary conference, as was utilized in the presented case report, may be the best approach to treatment planning for these patients at this time.

LEVEL OF EVIDENCE

4. Laryngoscope, 128:1083-1092, 2018.

A case of central mucoepidermoid carcinoma associated with dentigerous cyst

Mucoepidermoid carcinoma (MEC) is the most common malignant salivary gland neoplasm. Central MEC (CMEC) is a rare primary intraosseous bony lesion with an incidence of 2%–4.3% of all MECs reported. In this article, we present a rare case of a CMEC in the anterior region of maxilla at a 43-year-old female patient that was arising from a dentigerous cyst. CMECs are extremely rare tumor. They are usually low-grade lesions with favorable prognosis. Odontogenic cysts are one of the origins of this lesion. Treatment of impacted tooth is necessary in the early stage for prevention of this neoplasm.

Malignant changes developing from odontogenic cysts: A systematic review

The aim of this study was to systematically review scientific literature in orderto describe the characteristics and prognosis of malignant entities developing from odontogenic cysts. A search in Pubmed (MEDLINE) and Cochrane databases was conducted. The inclusion criteria were articles published in English related to the malignisation of odontogenic cysts in humans. The exclusion criteria were articles that do not specify the type of odontogenic cyst, malignisation of parakeratinised keratocysts, the presence of an ameloblastic carcinoma and metastasis from distant primary tumours. The selected articles were classified according to Strength of Recommendation Taxonomy criteria. Statistical analysis of the data was carried out using statistical package software SPSS version 22.0. From the 1,237 articles initially obtained, the authors included 3 case series and 45 case reports in the end. Descriptive analysis showed that men have a disposition for malignisation from odontogenic cysts and they frequently appear at the posterior mandible, with pain and swelling being the most frequent signs and symptoms. Follicular cysts were the entities that underwent the most malignant changes with well differentiated squamous cell carcinomas being the most prevalent type of malignancy. The real prognosis of this malignancy is not known because of the heterogeneity of available studies.

Key words:Odontogenic cysts, squamous cell carcinoma, neoplastic cell transformation, oral cancer.

Central mucoepidermoid carcinoma radiographically mimicking an odontogenic tumor: A case report and literature review

Central mucoepidermoid carcinoma (CMC) of the jaw bones is a rare malignant salivary gland tumor of unknown pathogenesis, comprising about 4% of all mucoepidermoid carcinomas (MECs). Most cases are histologically classified as a low-grade tumor and radiographically appear as a well-defined unilocular or multilocular radiolucent lesion. Block resection or wide local excisions are the treatment of choice and patients usually show a good overall prognosis although a long-term follow-up is necessary. This report describes a case of a 28-year-old male with MEC in the posterior region of the mandible and discusses its clinical, radiographic and histopathological findings. Although rare, CMC may be considered a differential diagnosis in cases of proliferative and osteolytic lesions in the oral cavity even when its clinical and/or radiographic findings do not suggest malignancy.

Dentigerous Cyst Associated with Adenomatoid Odontogenic Tumour

Adenomatoid odontogenic tumour (AOT), a tumour composed of odontogenic epithelium, is an uncommon tumour of odontogenic origin that accounts for only 2.2- 7.1% of all odontogenic tumours. Very few cases of AOT associated with Dentigerous cyst (DC) have been reported till date, most cases are in females and have a striking tendency to occur in the anterior maxilla. The present case is that of a 14-year-old female who revealed a large radiolucent lesion associated with the crown of an unerupted canine located in the left maxillary anterior region. The microscopic examination revealed the presence of AOT in the fibrous capsule of a DC. In this paper, we describe the importance of grossing, sectioning and complete examination of the slide to diagnose such hybrid lesions.

Common Matrix Metalloproteinases (MMP-8, -9, -25, and -26) Cannot Explain Dentigerous Cyst Expansion

OBJECTIVE

Mechanisms of the dentigerous cyst formation from the normal eruption follicle is unknown but disturbances in the proteolytic activity have been suspected, since the growth of these cysts is accompanied by local bone destruction. The aim of the present study was to evaluate the expression of matrix metalloproteinases (MMP) in human dental dentigerous cysts and healthy dental follicles.

MATERIALS AND METHODS

We studied 10 patients with dentigerous cysts and 10 healthy dental follicles from the lower jaw in respect to their immunoexpression of MMPs -8, -9, -25, and -26 and tissue inhibitor of metalloproteinases -1 (TIMP-1).

RESULTS

MMP-8 was expressed slightly more in cyst epithelium than in odontogenic epithelium of healthy controls dental follicle but the difference lacked statistical difference. Other MMPs and TIMP-1 did not differ regarding the studied specimens.

CONCLUSION

Differences in MMP expression cannot solely explain the cyst expansion suggesting the potential involvement of other osteolytic mechanisms.