Spindle-cell variant of ameloblastic carcinoma: a report of 3 cases and demonstration of epithelial-mesenchymal transition in tumor progression

Ameloblastic carcinoma: A systematic review

BACKGROUND

Ameloblastic carcinoma (AC) is the most common odontogenic malignancy, constituting approximately 30% of cases in this category. Literature is sparse on malignant odontogenic neoplasms, with a large proportion of current knowledge derived from case reports or small case series.

METHODS

A systematic review of case series/case reports of AC was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) Statement guidelines. Demographic and clinical information, including duration of the lesion, location, clinical presentation and radiologic features, were analysed. Additionally, the origin of the lesion (primary/secondary), Ki-67 proliferation index, treatment performed, metastasis, tumour recurrence and prognosis were collected for analysis.

RESULTS

A total of 126 studies, including 285 individual cases of AC, were included in this review. Patients presented with a near-equal distribution of painless and painful swellings. ACs presented at a median age of 45 years, with a male-to-female ratio of 1:2. The mandible was most frequently involved, with rare cases extending to involve more than one region, including crossing the midline. Although most lesions presented with poorly-demarcated borders (52.6%), unilocular lesions with well-demarcated borders (47.4%) comprised a substantial number in the sample. The proliferation index was only reported in 27 cases, with a mean score of 42% and a wide range. The probability of tumour recurrence increased, and the survival probability decreased with prolonged follow-up duration.

CONCLUSION

This study provides more comprehensive, up-to-date descriptive data on these rare odontogenic malignancies, aiding clinicians and Pathologists with the diagnosis and surgeons in their management of cases.

Odontogenic Carcinosarcoma: Clinicopathologic and Molecular Features of Three Cases, a Literature Review and Nomenclature Proposal

BACKGROUND

Odontogenic carcinosarcoma (OCS) is a rare odontogenic malignancy with limited characterization and unexplored molecular features. We report clinicopathologic and molecular findings in 3 additional OCS and review the literature.

METHODS

3 OCS (5.1%) were identified among 59 malignant odontogenic tumors (in our archives from 1992 to 2022). Clinical, radiologic, histopathologic, immunophenotypic, and molecular findings were reviewed. Data from prior case reports and systematic or non-systematic reviews were extracted for analysis.

RESULTS

Three mandibular OCS (age range: 66 to 72 years; 1 male, 2 females) were identified. Case 1 had novel clear-cell morphology, multiple recurrences, and a lethal outcome 28 months after resection. EWSR1 rearrangements were negative, but the tumor showed focal nuclear β-catenin and strong LEF-1 immunoreactivity. Case 2 demonstrated ameloblastic and sclerosing features and encased the inferior alveolar nerve; the patient was disease-free 22 months after resection with adjuvant chemoradiation therapy. LEF-1 was again strongly positive, and next-generation sequencing demonstrated 9p region-(CDKN2A, CDKN2B) copy number loss, and 12q region-(MDM2, CDK4) copy number gain. Case 3 showed clear-cell and markedly sclerosing features; no follow-up information was available. Literature review along with the current cases yielded 20 cases. OCS showed a male predilection (1.5:1), mandibular predominance (80%, typically posterior), and a bimodal age distribution (modes: 27.7 years, 62.7 years). OCS presented as masses (100%), often with pain (55%), and paresthesia (45%). Tumors were typically radiolucent (88.9%), with bone destruction (61.1%), and/or tooth effacement (27.8%). Preoperative biopsy was sensitive for malignancy (85.7%). At least 45% show evidence for a precursor lesion. 3-year DSS and DFS were 58% and 35%, respectively. Regional and distant (usually lung) metastatic rates were 25% and 31.3%, respectively. Increased mitotic rates and presence of tumor necrosis trended toward worse DSS and DFS.

CONCLUSION

OCS is a rare but aggressive malignancy, often arising from precursor tumors and may represent a terminal phenotype rather than a distinct entity. We describe novel clear-cell and sclerosing morphologies. Wnt pathway alterations appear important. Mitotic rates and necrosis may be adverse prognosticators. In keeping with nomenclature trends in other sites, OCS may be more appropriately designated as "biphasic sarcomatoid odontogenic carcinomas."

Ameloblastic Carcinoma of the Maxilla: A Rare Case Report and Review of Literature from 1948 to 2021

Ameloblastic carcinoma is a rare malignant neoplasm arising from the odontogenic epithelium. Ameloblastic carcinoma commonly occurs de novo affecting the posterior segments of the mandible. Presently, only less than 100 cases have been reported arising from the maxilla. We report a unique case of maxillary ameloblastic carcinoma in a 68-year-old male with a 5.6 cm positron emission tomography (PET) avid left maxillary sinus mass. The patient underwent a left maxillectomy which revealed hyperchromatic and pleomorphic tumor cells arranged in a nested and trabecular architecture. The tumor cells showed distinct peripheral palisading with reverse polarization. Areas of bone destruction, necrosis, lymphovascular and perineural invasions, as well as atypical mitoses, were identified. Immunohistochemically, the tumor cells were positive for keratin cocktail (AE1/AE3 and CAM 5.2), keratin 19, p40, and weakly positive for MDM2, while negative for calretinin. Molecular analysis revealed wild-type BRAF; however, alterations in CDKN2A/B, MTAP, RB1, SMARCA4, STK11, FGF12, SETD2, and TP53 were present. This histopathologic and molecular profile supported the diagnosis of ameloblastic carcinoma. There has been no evidence of disease recurrence or metastasis eleven months after the initial diagnosis.

Comparative Analysis Between Dentinogenic Ghost Cell Tumor and Ghost Cell Odontogenic Carcinoma: A Systematic Review

Dentinogenic ghost cell tumor (DGCT) and ghost cell odontogenic carcinoma (GCOC) form a spectrum of rare benign and malignant odontogenic neoplasms, respectively. The aim of this study was to perform a comparative systematic review of the clinicopathological, genetic, therapeutic, and prognostic features of DGCT and GCOC. The electronic search was performed until December 2020 on seven electronic databases. Case reports, series, and research studies with enough histopathological criteria for diagnosis and all genomic studies were included. Both DGCT and GCOC showed a male prevalence (p = 0.043), with mandibular and maxillary predilections, respectively (p = 0.008). Peripheral DGCT (DGCTp) affected most elderly people (p < 0.001), and central DGCT (DGCTc) and GCOC occurred mainly in younger individuals. Unilateral enlargement of maxilla or mandible was the most common clinical sign associated with a radiolucent or mixed image. Ameloblastomatous epithelium was often present in both neoplasms. Basaloid and large cells with vesicular nuclei were also frequently seen in GCOC. β-catenin expression and mutations (CTNNB1 gene) were found in DGCT and GCOC. Conservative surgery was mostly used for DGCTp, while radical resection was chosen for DGCTc and GCOC. High recurrence rates were found in DGCTc and GCOC. Metastasis occurred in 16.7% of GCOC cases and the 5-year survival rate was 72.6%. DGCT and GCOC share numerous clinicopathological features and demand a careful histopathological evaluation, considering the overlap features with other odontogenic tumors and the possibility of malignant transformation of DGCT. A strict regular post-operative follow-up is mandatory due to high recurrence rates and metastatic capacity in GCOC.

Report of a Rare Case of Spindle Cell Ameloblastic Carcinoma and the Diagnostic Utility of Immunohistochemistry

Ameloblastic carcinoma is a rare aggressive malignant epithelial odontogenic tumor. The spindle cell variant of ameloblastic carcinoma (SCAC) is exceedingly rare with 15 cases of SCAC having been reported. Therefore, because of the paucity of cases in literature related to SCAC, the biological behavior of the entity has not been well evaluated. Herein the authors report a case of incidentally diagnosed SCAC in a 20-year-old woman identified on imaging as part of the evaluation of a work-related facial injury. Histologically, the tumor had background of cystic ameloblastoma with areas of dense hypercellular spindle cells with short-to-long intersecting fascicles and occasional herringbone pattern intermixed with solid epithelial nests. Both the epithelial and spindle cells were positive for cytokeratin including cytokeratin 19, D2-40, and transducin-like enhancer of split proteins-1 immunohistochemical stains. The patient was followed for 18 months with no evidence of recurrence or metastasis. To the knowledge this is a first case of reporting D2-40 positivity in spindle ameloblastic carcinoma and this immunostain could be used as helpful marker to diagnose this entity.

Hypoxia-induced HIF-1α and ZEB1 are critical for the malignant transformation of ameloblastoma via TGF-β-dependent EMT

Ameloblastic carcinoma (AC) is defined as a rare primary epithelial odontogenic malignant neoplasm and the malignant counterpart of benign epithelial odontogenic tumor of ameloblastoma (AB) by the WHO classification. AC develops pulmonary metastasis in about one third of the patients and reveals a poor prognosis. However, the mechanisms of AC oncogenesis remain unclear. In this report, we aimed to clarify the mechanisms of malignant transformation of AB or AC carcinogenesis. The relatively important genes in the malignant transformation of AB were screened by DNA microarray analysis, and the expression and localization of related proteins were examined by immunohistochemistry using samples of AB and secondary AC. Two genes of hypoxia-inducible factor 1 alpha subunit (HIF1A) and zinc finger E-box-binding homeobox 1 (ZEB1) were significantly and relatively upregulated in AC than in AB. Both genes were closely related in hypoxia and epithelial-mesenchymal transition (EMT). In addition, expressions of HIF-1α and ZEB1 proteins were significantly stronger in AC than in AB. In the cell assays using ameloblastoma cell line, AM-1, hypoxia condition upregulated the expression of transforming growth factor-β (TGF-β) and induced EMT. Furthermore, the hypoxia-induced morphological change and cell migration ability were inhibited by an antiallergic medicine tranilast. Finally, we concluded that hypoxia-induced HIF-1α and ZEB1 were critical for the malignant transformation of AB via TGF-β-dependent EMT. Then, both HIF-1α and ZEB1 could be potential biomarkers to predict the malignant transformation of AB.