Diagnostic significance of NM23 protein in ameloblastoma and ameloblastic carcinoma: An immunohistochemical study.

BACKGROUND: Clinico-histopathologic assessment of patients with ameloblastoma and ameloblastic carcinoma remains the best diagnostic modality for the tumors. However, in cases where the criteria for arriving at a definitive diagnosis are not clearcut, the pathologist is faced with a dilemma and thus an imperative need for adjunct diagnostic methods. OBJECTIVES: To evaluate/compare the immunohistochemical expression of NM23 in classical, borderline (atypical) ameloblastoma and ameloblastic carcinoma and to assess usefulness of NM23 in closing diagnostic gaps between ameloblastoma and ameloblastic carcinoma. METHODS: Twenty-four (24) cases of ameloblastoma, 10 ameloblastoma with classical histopathologic features, 8 with nonclassical histopathology [atypical], and 6 cases of ameloblastic carcinoma were selected from cases seen at the Oral Pathology Laboratory of the Lagos State University College of Medicine, Nigeria. NM23 immunostaining protocol was done on the selected tissue blocks and evaluated using Sinicrope method. Analysis was done using R language. RESULTS: Positive NM23 staining was observed in all cases of ameloblastoma and ameloblastic carcinoma, with more intense staining observed in the stellate reticulum-like areas than in the ameloblast-like areas. Ameloblastic carcinoma stained intensely with NM23 (100%) compared with atypical cases (37.5%) and ameloblastoma (20.0%; p = 0.04). The mean aggregate score was also significantly higher in AC (11 ± 2.4; p = 0.01). The mean aggregate score was also significant amongst growth pattern of ameloblastoma (p = 0 0.02). CONCLUSIONS: The findings in this study reveal the usefulness of NM23 in differentiating ameloblastoma from ameloblastic carcinoma; a more comprehensive study with a larger sample size is recommended to corroborate or refute the findings in this study.

SATB2 and MDM2 Immunoexpression and Diagnostic Role in Primary Osteosarcomas of the Jaw.

Primary osteosarcomas of the jaw (OSJ) are rare, accounting for 6% of all osteosarcomas. This study aims to determine the value of SATB2 and MDM2 immunohistochemistry (IHC) in differentiating OSJ from other jawbone mimickers, such as benign fibro-osseous lesions (BFOLs) of the jaw or Ewing sarcoma of the jaw. Certain subsets of osteosarcoma harbor a supernumerary ring and/or giant marker chromosomes with amplification of the 12q13-15 region, including the murine double-minute type 2 (MDM2) and cyclin-dependent kinase 4 (CDK4) genes. Special AT-rich sequence-binding protein 2 (SATB2) is an immunophenotypic marker for osteoblastic differentiation. Cases of OSJ, BFOLs (ossifying fibroma and fibrous dysplasia) of the jaw, and Ewing sarcoma of the jaw were retrieved from the Departments of Oral Pathology and Oral Medicine, Faculty of Dentistry, Obafemi Awolowo University and Lagos State University College of Medicine, Nigeria. All OSJ retrieved showed histologic features of high-grade osteosarcoma. IHC for SATB2 (clone EP281) and MDM2 (clone IF2), as well as fluorescence in situ hybridization (FISH) for MDM2 amplification, were performed on all cases. SATB2 was expressed in a strong intensity and diffuse staining pattern in all cases (11 OSJ, including a small-cell variant, 7 ossifying fibromas, and 5 fibrous dysplasias) except in Ewing sarcoma, where it was negative in neoplastic cells. MDM2 was expressed in a weak to moderate intensity and scattered focal to limited diffuse staining pattern in 27% (3/11) of cases of OSJ and negative in all BFOLs and the Ewing sarcoma. MDM2 amplification was negative by FISH in interpretable cases. In conclusion, the three cases of high-grade OSJs that expressed MDM2 may have undergone transformation from a low-grade osteosarcoma (LGOS). SATB2 is not a dependable diagnostic marker to differentiate OSJ from BFOLs of the jaw; however, it could serve as a valuable diagnostic marker in differentiating the small-cell variant of OSJ from Ewing sarcoma of the jaw, while MDM2 may be a useful diagnostic marker in differentiating OSJ from BFOLs of the jaw, especially in the case of an LGOS or high-grade transformed osteosarcoma.

BRAF V600E mutation-specific immunohistochemical analysis in ameloblastomas: a 44-patient cohort study from a single institution.

PURPOSE: The aim of this study is to investigate the presence and prevalence of BRAF V600E mutation in ameloblastomas using anti-BRAF V600E monoclonal antibody (VE1 clone) and to identify any clinicopathologic correlation with BRAF V600E mutation in ameloblastoma. MATERIALS AND METHODS: The pathology files of the Department of Oral Pathology and Oral Medicine, Faculty of Dentistry, Lagos State University College of Medicine, Lagos, Nigeria, were searched for the diagnosis of ameloblastoma from 2016 to 2020. Archived non-decalcified formalin-fixed paraffin-embedded tissue underwent immunohistochemistry using anti-BRAF V600E antibody at the University of Pittsburgh, Pennsylvania. Clinicopathologic data such as age at diagnosis, gender, jaw bone involved (mandible or maxilla), tumor location (anterior or posterior) and histologic subtype were collected. The clinicopathologic parameters were analyzed using Chi-square test and Fisher's exact test according to the BRAF status. RESULTS: Forty-four cases of ameloblastoma were retrieved. The male to female ratio was 1.32:1. The average age of patients at diagnosis was 33.3 years. Thirty-nine cases were located in the mandible and 5 cases in the maxilla. Only cases in the mandible were positive for anti-BRAF V600E antibody (n = 15/39; 38.5%). There was a significant correlation between BRAF V600E expression in mandibular tumors and histologic subtype (p = 0.02); however, no significance was observed for gender, age and tumor location. CONCLUSION: BRAF V600E mutation preferentially occurs in mandibular ameloblastomas, especially in non-plexiform ameloblastomas. These patients may benefit therapeutically from the use of BRAF inhibitors.

A geographical analysis of ethnic distribution of jaw ameloblastoma in Nigerians.

INTRODUCTION: Ameloblastoma is the most common odontogenic tumour in Nigeria. A definite geographic variation has been observed in the frequency of odontogenic tumors from different parts of the world. However, there is no study on the regional variations in Nigeria. Hence, this study was designed to document the ethnic and geographical distribution of jaw ameloblastoma in Nigeria. METHODS: Archival data on ameloblastoma from 10 health facilities were obtained. Global Moran's I detected geographic clustering in its distribution while Local Getis Ord indicated the location of ameloblastoma clusters. Chi-square tested associations between variables at 0.05 level of significance. RESULTS: A total of 1,246 ameloblastoma cases were recorded in Nigeria. Besides substantial state variations, a South-North gradient was noticed in its distribution. Significant positive spatial autocorrelation was observed in the three major groups while ameloblastoma hotspots were found in the SouthWestern and Northwestern Nigeria. The Igbos had a higher prevalence of ameloblastoma outside their home region than within. CONCLUSION: The study hypothesized that the geographical distribution of ameloblastoma in Nigeria is the result of all or one of the following: the country's tropical climate, migration patterns and health seeking behavior. Hopefully, these claims should lead to further enquiry on the underlying causes.

Biological profile of ameloblastoma and its location in the jaw in 1246 Nigerians.

OBJECTIVES: Ameloblastoma is a benign, slow-growing, locally invasive epithelial tumor of odontogenic origin, with unlimited growth capacity and a strong tendency to recur. This multicentric study analyzed ameloblastoma diagnosed in Nigeria among different ethnic groups. STUDY DESIGN: This retrospective study included ameloblastoma cases diagnosed from 1964 to 2017 at 10 hospitals or medical centers in Nigeria. Age, sex, tribe, and location of the ameloblastoma in the jaw were analyzed. Associations between variables were tested by using χ2 and Fisher's exact test. RESULTS: A total of 1246 ameloblastoma cases were recorded (mean patient age 32.51 ± 14.54 years; range 4-86 years; male-to-female ratio 1.2:1). Approximately 60% of ameloblastoma cases occurred in young adults (age range 18-40 years). Ninety-eight lesions were located in the maxilla and 1103 in the mandible; the posterior mandible was the most common site (31.3% on the right and 26.5% on the left, respectively), followed by the anterior (26.0%) mandible. No significant differences were noted in the distribution of ameloblastoma within the tribes with respect to age (P = .92) and sex (P = .71). CONCLUSIONS: The mandible is a common site of ameloblastoma in patients in Nigeria, and in most cases, it occurs in young adults. Early presentation, diagnosis, and treatment are important to reduce postoperative disfigurement and morbidity.

Bimaxillary keratocystic odontogenic tumour: a case of diagnostic and therapeutic difficulty.

Keratocystic odontogenic tumour (KCOT) is a benign cystic intraosseous tumour of odontogenic origin that is usually solitary except when syndromic. It rarely occurs in the maxilla; therefore a rapidly progressive, nonsyndromic bimaxillary KCOT with locoregional extension poses significant diagnostic and management challenges. To the best of the authors' knowledge, documentation of a nonsyndromic bimaxillary KCOT is nonexistent in the English literature. We therefore present the case of an extensive bimaxillary KCOT in a 38-year-old Nigerian male.

Clear cell variant of squamous cell carcinoma of skin: A report of a case.

Clear cell squamous cell carcinoma (SCC) is a rare variant of SCC of skin in which ultraviolet radiation has been suggested as possible etiology. This case is that of a 62-year-old male concrete block maker/bricklayer who presented with a 6 months history of a non-healing ulcer on the left side of his face. Histology showed features of malignant epithelial neoplasm composed of islands of large oval to polyhedral malignant squamous cells with eosinophilic to amphophilic cytoplasm and vesicular nuclei and there were areas showing clear cell differentiation and isolated areas of keratin pearl formation. The lesion was also negative for periodic acid schiff, mucicarmine, and alcian blue stains but was strongly positive for AE1/AE3 (immuno-stain). This case showed an aggressive and bizarre clinical presentation but more report of cases are needed to have a better characterization of the clinical presentation and prognosis of this variant of SCC.

A review of 413 salivary gland tumours in the head and neck region.

OBJECTIVES: Salivary gland tumours (SGTs) are a group of heterogeneous lesions with complex clinico-pathological characteristics and distinct biological behaviours. Previous studies have reported geographic variations in site distribution, incidence and histological types of SGTs. The aim of this study was to describe the demography of SGTs seen at a tertiary health centre and compare findings with previous studies. STUDY DESIGN: Data on SGTs from archives of the Department of Oral Pathology and the Department of Pathology, University College Hospital Ibadan were retrieved. Information about histological types, age, sex and location were analyzed using SPSS for Window (version 20.0; SPSS Inc. Chicago, IL). Reactive and tumor-like lesions such as sialometaplasia, benign lymphoepithelial lesion, lymphoepithelial cyst, mucocele, mucous extravasation phenomenon, ranula, and sialosis were excluded from the study. RESULTS: 413 SGTs consisting of 221 (53.5%) malignant and 192 (46.5%) benign lesions were seen. SGTs occurred more in females (50.6%) than males (49.4%) with a mean age of 43.7 (±16.9) years and peak age in the fifth decade of life. The parotid with 171 (41.4%) cases was the commonest site, followed by palate with 89 (21.5%) cases, while only 7(1.7%) cases were seen in sublingual gland. Pleomorphic adenoma with 169 (40.9%) was the most frequent SGT followed by adenoid cystic carcinoma with 93 (22.5%) cases which also was the most frequent malignant SGT while only 3 (0.7%) cases of Warthin's tumour were seen. CONCLUSION: This report is one of few that showed a higher occurrence of malignant SGTs compared to their benign counterparts. The findings were essentially similar to findings in Africa but showed SGTs to be more common in females. The reason(s) for high occurrence of malignant SGTs in minor salivary glands and the rarity of Warthins tumour in this study and other African series compared to those from America needs further investigation. Key words:Salivary gland tumours, parotid gland, pleomorphic adenoma, adenoid cystic carcinoma, warthin's tumour.