Elizabeth A. Bilodeau

Clear cell odontogenic carcinomas show EWSR1 rearrangements: a novel finding and a biological link to salivary clear cell carcinomas.

Clear cell odontogenic carcinomas (CCOCs) are a rare tumor of the jaws, which have considerable morphologic and immunophenotypic overlap with (hyalinizing) clear cell carcinomas (CCCs) of salivary origin. Fluorescence in situ hybridization for EWSR1 was performed on 12 CCOCs, 14 CCCs, and a control set of other miscellaneous clear cell tumors of the head and neck region. EWSR1 was rearranged in 12/13 (92.3%) CCCs and 5/8 (62.5%) CCOCs. EWSR1 testing failed in 1 CCC and 4 CCOCs. Two cases initially diagnosed as CCOCs that were negative for the EWSR1 translocation, were reclassified as clear cell calcifying epithelial odontogenic tumors. ATF1 involvement was confirmed by fluorescence in situ hybridization analysis in 1 CCOC. In this study, we demonstrate for the first time the EWSR1-ATF1 translocation in a CCOC and demonstrate a concrete link between CCCs and at least a subset of CCOCs.

Clear Cell Carcinoma and Clear Cell Odontogenic Carcinoma: a Comparative Clinicopathologic and Immunohistochemical Study

Clear cell carcinoma or hyalinizing clear cell carcinoma (CCC) and clear cell odontogenic carcinoma (CCOC) are rare, low-grade and typically indolent malignancies that can be diagnostically challenging. In this study the clinicopathologic, histologic, and immunohistochemical features of 17 CCCs and 12 CCOCs are examined. The differential diagnosis of clear cell malignancies in the head and neck is discussed. The relationship of CCCs and CCOCs to other clear cell tumors on the basis of their immunohistochemical staining patterns is postulated.

Oral squamous cell carcinoma with mandibular bone invasion: intraoperative evaluation of bone margins by routine frozen section.

The intraoperative knowledge of margin status on mandibulectomy specimens is important for primary reconstruction. The goal of this study was to evaluate whether intraoperative bone marrow (BM) curettings and inferior alveolar nerve (IAN) biopsies are representative of final decalcified cross-sectional (shave) mandibular bone margins. Forty-seven margins in 27 patients consecutively treated with segmental mandibulectomy for squamous cell carcinoma were reviewed. These patients had BM or IAN margins sampled by surgeons and assessed intraoperatively by routine frozen section. The full cross-section of mandibular bone margins were sampled by pathologists at the time of routine gross examination. Intraoperative evaluation of BM/IAN biopsies is characterized by a 50% sensitivity (3 of 6 cases were false negative) and a 100% specificity. IAN biopsies are representative of the final bone margin. Given the technical feasibility of intraoperative BM and IAN assessment, we favor routine intraoperative evaluation of mandibular bone margins. However, even when bone margins are sampled intraoperatively, obtaining a full cross-section of the bone margin at the time of gross examination should also be performed as it remains the most accurate modality of bone margin assessment.

A comparative analysis of LEF-1 in odontogenic and salivary tumors☆

LEF-1 is a nuclear transcription factor of the Wnt pathway that regulates multipotent skin stem cell differentiation. β-Catenin is considered a transcriptional coactivator that interacts with LEF-1.This study evaluates LEF-1 in a variety of odontogenic and salivary tumors and determines the prevalence of β-catenin coexpression. Ninety-eight salivary gland tumors and 51 odontogenic tumors were evaluated for LEF-1 and β-catenin immunohistochemical staining. Positivity was defined as at least 2+ intensity in more than 50% of tumor cells, which required a composite score of 6 or more. LEF-1 was positive in 64% (7/11) of calcifying cystic odontogenic tumors (CCOT). Nuclear β-catenin was present in 82% (9/11) of CCOT. Coexpression of LEF-1 and nuclear β-catenin was noted in all LEF-1-positive CCOT. Strong and diffuse LEF-1 expression was seen in 69% (11/16) of basal cell adenocarcinomas (BCAC) and 63% (5/8) of basal cell adenomas (BA). Nuclear β-catenin was present in 50% (4/8) of BA and 43% (6/14) of BCAC. For BA, 4 of 5 LEF-1-positive tumors showed coexpression of β-catenin, and for BCAC, 5 of 9 LEF-1-positive tumors showed coexpression. In conclusion, this study documents for the first time the presence of LEF-1 expression and nuclear β-catenin coexpression in select basaloid salivary gland tumors and various odontogenic tumors. We demonstrate LEF-1 expression in both BA and BCAC preferentially over other salivary gland tumors suggesting some utility as a diagnostic marker.

Ewing sarcoma of the thyroid: Report of 2 cases and review of the literature

Neuroendocrine tumors of the thyroid encompass a wide differential diagnosis. The most common is medullary thyroid carcinoma. One must consider other possibilities when a neuroendocrine thyroid tumor is calcitonin negative. We report 2 cases of Ewing sarcoma of the thyroid and discuss the differential diagnosis and workup of a calcitonin‐negative neuroendocrine tumor of the thyroid.

Hyalinizing clear cell carcinoma of the head and neck: Case series and update

Hyalinizing clear cell carcinoma (HCCC) is a rare neoplasm of salivary gland origin which is low‐grade in nature. In this series, we report on 9 cases of HCCC and update the literature.

An in vivo model to assess magnesium alloys and their biological effect on human bone marrow stromal cells.

UNLABELLED Magnesium (Mg) alloys have many unique qualities which make them ideal candidates for bone fixation devices, including biocompatibility and degradation in vivo. Despite a rise in Mg alloy production and research, there remains no standardized system to assess their degradation or biological effect on human stem cells in vivo. In this study, we developed a novel in vivo model to assess Mg alloys for craniofacial and orthopedic applications. Our model consists of a collagen sponge seeded with human bone marrow stromal cells (hBMSCs) around a central Mg alloy rod. These scaffolds were implanted subcutaneously in mice and analyzed after eight weeks. Alloy degradation and biological effect were determined by microcomputed tomography (microCT), histological staining, and immunohistochemistry (IHC). MicroCT showed greater volume loss for pure Mg compared to AZ31 after eight weeks in vivo. Histological analysis showed that hBMSCs were retained around the Mg implants after 8 weeks. Furthermore, immunohistochemistry showed the expression of dentin matrix protein 1 and osteopontin around both pure Mg and AZ31 with implanted hBMSCs. In addition, histological sections showed a thin mineral layer around all degrading alloys at the alloy-tissue interface. In conclusion, our data show that degrading pure Mg and AZ31 implants are cytocompatible and do not inhibit the osteogenic property of hBMSCs in vivo. These results demonstrate that this model can be used to efficiently assess the biological effect of corroding Mg alloys in vivo. Importantly, this model may be modified to accommodate additional cell types and clinical applications. STATEMENT OF SIGNIFICANCE Magnesium (Mg) alloys have been investigated as ideal candidates for bone fixation devices due to high biocompatibility and degradation in vivo, and there is a growing need of establishing an efficient in vivo material screening system. In this study, we assessed degradation rate and biological effect of Mg alloys by transplanting Mg alloy rod with human bone marrow stromal cells seeded on collagen sponge subcutaneously in mice. After 8 weeks, samples were analyzed by microcomputed tomography and histological staining. Our data show that degrading Mg alloys are cytocompatible and do not inhibit the osteogenic property of hBMSCs in vivo. These results demonstrate that this model can be used to efficiently assess the biological effect of corroding Mg alloys in vivo.

Odontogenic Cysts and Neoplasms

This article reviews a myriad of common and uncommon odontogenic cysts and tumors. The clinical presentation, gross and microscopic features, differential diagnosis, prognosis, and diagnostic pitfalls are addressed for inflammatory cysts (periapical cyst, mandibular infected buccal cyst/paradental cyst), developmental cysts (dentigerous, lateral periodontal, glandular odontogenic, orthokeratinized odontogenic cyst), benign tumors (keratocystic odontogenic tumor, ameloblastoma, adenomatoid odontogenic tumor, calcifying epithelial odontogenic tumor, ameloblastic fibroma and fibroodontoma, odontoma, squamous odontogenic tumor, calcifying cystic odontogenic tumor, primordial odontogenic tumor, central odontogenic fibroma, and odontogenic myxomas), and malignant tumors (clear cell odontogenic carcinoma, ameloblastic carcinoma, ameloblastic fibrosarcoma).

Case Report: a Pediatric Case of Cementoblastoma with Histologic and Radiographic Features of an Osteoblastoma and Osteosarcoma

One case of an expansile mass involving the roots of a mandibular left first molar in a nine year old male is presented. The lesion has features of a cementoblastoma (CB), osteoblastoma (OB), and osteosarcoma (OS) both radiographically and histologically. Radiographically, a “sunburst” appearance is present. Histologically, the lesional tissue is intimately involved with the root, not the periosteum. The clinical, radiographic, and histopathologic characteristics of CB, OB, and OS are discussed as well as the difficulties associated with distinguishing between these lesions in the gnathic region.

Ectomesenchymal Chondromyxoid Tumor: A Series of Seven Cases and Review of the Literature.

Ectomesenchymal chondromyxoid tumors (ECT) are rare, benign, intraoral mesenchymal soft tissue tumors that can be diagnostically challenging. In this study the demographic, clinical, histopathologic, and immunohistochemical features of seven ECTs are examined. The differential diagnosis of this rare neoplasm is discussed and the literature is reviewed.