Tumors with EWSR1-CREB1 and EWSR1-ATF1 fusions: the current status

Envisioning the next WHO head and neck classification

The next WHO classification should abandon "salivary duct carcinoma"; conventional salivary duct carcinoma should be classified as "high-grade salivary duct carcinoma". Low-grade salivary duct carcinoma should replace the current nosology of "low-grade cribriform cystadenocarcinoma". Cystadenocarcinoma should be classified with the descriptor "Not Otherwise Specified" and should be considered an exclusionary diagnostic category. On the other hand, "Not Otherwise Specified" does not fit for hyalinizing clear cell carcinoma (HCCC). The EWSR1-ATF1 fusion is specific for HCCC within the context of salivary neoplasia. We recommend adding "hyalinizing" even though this feature is not present in all cases; the benefit of which is the mental association with a salivary clear cell malignancy. Sinonasal Renal Cell-like Adenocarcinoma (SNRCLA) is a distinct clear cell neoplasm and should be added to the next WHO classification. Future studies will bear out whether SNRCLA is even a low-grade carcinoma, or may be reclassified as "adenoma". Lastly, the next WHO monograph should include the Risk Model in the general introductory statements on oral squamous cell carcinoma, under a subheading of "Histological Prognosticators". The positive predictive value for developing locoregional recurrence in patients with low-stage oral cavity squamous carcinoma (OSCC) and "worst pattern of invasion type-5" (WPOI-5) is 42 %. Low-stage high-risk OSCC with a combination of features other than WPOI-5 is associated with 32 % likelihood for locoregional progression. WPOI-5 also predicts occult metastatic disease (p = 0.0001, Chi squared, 2 DF). Thus the Risk Model can also be used to make decisions regarding staged elective neck dissections.

EWSR1 and ATF1 rearrangements in clear cell odontogenic carcinoma: presentation of a case

Clear cell odontogenic carcinoma (CCOC) is a rare odontogenic tumor of the jaws that is more common in the mandible than maxilla and has a female preponderance with a peak incidence in the sixth decade. It is characterized by locally aggressive behavior and has the potential to metastasize. This tumor was recently reported to have a rearrangement of the Ewing sarcoma breakpoint region 1 gene (EWS RNA-binding protein 1, EWSR1) in 5 of 8 cases tested and of the activating transcription factor 1 gene (ATF1) in 1 case tested. We report a case of CCOC in the premolar area of the mandible in a 59-year-old woman. This case demonstrated the presence of both EWSR1 and ATF1 gene rearrangements by fluorescence in situ hybridization.

Pitfalls in the biopsy diagnosis of intraoral minor salivary gland neoplasms: diagnostic considerations and recommended approach

Among the more common types of intraoral minor salivary gland neoplasms are pleomorphic adenoma, basal cell adenoma, polymorphous low-grade adenocarcinoma, and adenoid cystic carcinoma. These minor salivary gland neoplasms share similar morphologic features and to a large extent immunohistochemical findings. Differentiation between these benign and malignant neoplasms is often predicated on the presence or absence of invasion. As such, in the presence of limited tissue sampling that typifies the initial testing modalities, including fine needle aspiration biopsy and/or incisional biopsy, it often is not possible to differentiate a benign from malignant minor salivary gland neoplasm. The diagnostic difficulties arise from the absence in needle or incisional biopsy of the tumor's periphery to determine whether infiltrative growth is or is not present. In this manuscript we discuss limitations and considerations associated with evaluation of incisional biopsies of intraoral minor salivary gland tumors. We offer a diagnostic approach to evaluating these biopsies, and suggest diagnostic terminology for biopsy specimens in which distinction between benignancy and malignancy is not feasible. The pathologist's approach to this distinction is critical, as treatment of benign neoplasms is generally conservative, whereas malignant lesions may warrant more aggressive management.

The role of cytogenetics and molecular diagnostics in the diagnosis of soft-tissue tumors

Soft-tissue sarcomas are rare, comprising <1% of all cancer diagnoses. Yet the diversity of histological subtypes is impressive with >100 benign and malignant soft-tissue tumor entities defined. Not infrequently, these neoplasms exhibit overlapping clinicopathologic features posing significant challenges in rendering a definitive diagnosis and optimal therapy. Advances in cytogenetic and molecular science have led to the discovery of genetic events in soft-tissue tumors that have not only enriched our understanding of the underlying biology of these neoplasms but have also proven to be powerful diagnostic adjuncts and/or indicators of molecular targeted therapy. In particular, many soft-tissue tumors are characterized by recurrent chromosomal rearrangements that produce specific gene fusions. For pathologists, identification of these fusions as well as other characteristic mutational alterations aids in precise subclassification. This review will address known recurrent or tumor-specific genetic events in soft-tissue tumors and discuss the molecular approaches commonly used in clinical practice to identify them. Emphasis is placed on the role of molecular pathology in the management of soft-tissue tumors. Familiarity with these genetic events provides important ancillary testing for pathologists to include in their diagnostic armamentarium.

Molecular pathology of melanocytic tumors

Genetic and genomic analyses of melanocytic tumors have yielded new opportunities for improvements in diagnostic accuracy for the distinction of nevus from melanoma and better selection of patients affected by melanoma for targeted treatment. Since chromosomal copy number changes are commonly found in malignant melanoma, but rare in melanocytic nevi, cytogenetic assays have emerged as a promising ancillary study for the workup of melanocytic tumors with ambiguous light microscopic features. Comparative genomic hybridization (CGH) permits assessment of the full set of chromosomes, but requires a significant amount of lesional tissue, and may fail to detect aberrations in a minor subpopulation of tumor cells. Fluorescence in situ hybridization (FISH) is the cytogenetic assay of choice for limited amounts of tissue. FISH targets only specific chromosomes, with inherent limitations in test sensitivity and specificity. FISH analysis is also heavily dependent on individual experience. Molecular studies have identified distinct sets of mutations in melanoma and/or nevi. These mutations have become clinically relevant for targeted therapy of patients with advanced disease, especially for the treatment of patients with metastatic melanoma carrying the BRAF(V600) or KIT mutations. However, mutation analysis can on occasion also be used for diagnostic purposes.

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.

JAZF1 rearrangement in a mesenchymal tumor of nonendometrial stromal origin: report of an unusual ossifying sarcoma of the heart demonstrating JAZF1/PHF1 fusion

Rearrangements of JAZF1 are a frequent genetic aberration in endometrial stromal tumors. We report a distinct primary cardiac ossifying sarcoma that harbored a JAZF1/PHF1 fusion. The patient was a 70-year-old man with a history of a 6.8 cm calcific intramural left ventricular mass. Six years after his initial evaluation, the patient developed multiple lung metastases and ultimately died of disease-related complications. Histologically, the cardiac tumor and lung metastases demonstrated an infiltrative, malignant spindle cell neoplasm that grew in short fascicles with areas of bone formation, nuclear palisading, and necrosis. The neoplastic cells were relatively monomorphic in a background of an amorphous collagenous matrix. Immunohistochemical analysis was positive for vimentin and negative for wide-spectrum cytokeratins, S100 protein, desmin, smooth muscle actin, and CD34. Fluorescence in situ hybridization using a dual-color, single-fusion probe set identified the JAZF1/PHF1 fusion. The unique morphology and the presence of a JAZF1/PHF1 rearrangement suggest that this distinctive ossifying sarcoma is not part of a currently established diagnostic entity, representing instead a novel primary cardiac sarcoma. This case also represents the first description of a JAZF1 fusion in a tumor outside the spectrum of endometrial stromal neoplasms.

The Molecular Pathology of Salivary Gland Tumors with Translocations

Presented here are the salivary gland tumors now recognized to have significant and highly prevalent translocations. These include both common and uncommon malignancies: mucoepidermoid carcinoma, adenoid cystic carcinoma, mammary analog secretory carcinoma, and clear cell carcinoma. These mutations have potential diagnostic applications, particularly in difficult and challenging variant morphologies are unusually challenging differential diagnoses. Practical applications of the molecular pathology of these tumors is discussed. The mutational assessment may also prove to have therapeutic importance, as targeted therapies may be generated for these tumors in the future.

Cytogenetic and mutational analyses of melanocytic tumors

Analyses of genetic and genomic alterations of melanocytic tumors have not only led to a better understanding of the pathogenesis of melanocytic tumors but also created new opportunities for improvements in diagnostic accuracy in distinguishing nevus from melanoma, and more effective treatments for patients affected by melanoma. Cytogenetic tests have emerged as a promising ancillary method for the workup of diagnostically problematic melanocytic tumors with ambiguous light microscopic features. Mutation analysis not only is important in treatment decision making but also can be used for improved diagnostic accuracy, staging, and prognosis.

P6981, an arylstibonic acid, is a novel low nanomolar inhibitor of cAMP response element-binding protein binding to DNA

Several basic leucine zipper (B-ZIP) transcription factors have been implicated in cancer, substance abuse, and other pathological conditions. We previously identified arylstibonic acids that bind to B-ZIP proteins and inhibit their interaction with DNA. In this study, we used electrophoretic mobility shift assay to analyze 46 arylstibonic acids for their activity to disrupt the DNA binding of three B-ZIP [CCAAT/enhancer-binding protein α, cyclic AMP-response element-binding protein (CREB), and vitellogenin gene-binding protein (VBP)] and two basic helix-loop-helix leucine zipper (B-HLH-ZIP) [USF (upstream stimulating factor) and Mitf] proteins. Twenty-five arylstibonic acids showed activity at micromolar concentrations. The most active compound, P6981 [2-(3-stibonophenyl)malonic acid], had half-maximal inhibition at ~5 nM for CREB. Circular dichroism thermal denaturation studies indicated that P6981 binds both the B-ZIP domain and the leucine zipper. The crystal structure of an arylstibonic acid, NSC13778, bound to the VBP leucine zipper identified electrostatic interactions between both the stibonic and carboxylic acid groups of NSC13778 [(E)-3-(3-stibonophenyl)acrylic acid] and arginine side chains of VBP, which is also involved in interhelical salt bridges in the leucine zipper. P6981 induced GFP-B-ZIP chimeric proteins to partially localize to the cytoplasm, demonstrating that it is active in cells. P6981 inhibited the growth of a patient-derived clear cell sarcoma cell line whose oncogenic potential is driven by a chimeric protein EWS-ATF1 (Ewing's sarcoma protein-activating transcription factor 1), which contains the DNA binding domain of ATF1, a B-ZIP protein. NSC13778 inhibited the growth of xenografted clear cell sarcoma, and no toxicity was observed. These experiments suggest that antimony containing arylstibonic acids are promising leads for suppression of DNA binding activities of B-ZIP and B-HLH-ZIP transcription factors.