Pleomorphic Adenoma with a Novel Gene Rearrangement-LINC01606::PLAG1.

BACKGROUND: Pleomorphic adenoma is a well-known benign salivary gland neoplasm characterized by the presence of varying proportions of three different components, including bi-layered ducts, myoepithelial cells, and admixed within a chondromyxoid/fibrous stroma. METHOD: We report an interesting case of an adult male who presented with bleeding from an extensively degenerated parotid gland mass, concerning for a vascular neoplasm versus primary malignant tumor. Microscopically, majority of the viable tumor exhibited diffuse proliferation of spindle to epithelioid cells, with focal areas depicting cribriform glands, ducts, and scant chondromyxoid stroma. RESULT: Next-generation sequencing (NGS) RNA-based fusion panel analysis identified a gene rearrangement involving the pleomorphic adenoma gene 1 (PLAG1), with a novel, cryptogenic fusion partner known as LINC01606; [LINC01606::PLAG1; inv(8;8)(8q12.1;8q12.1)]. CONCLUSION: To the best of our knowledge, this is the first documented case of a long non-coding RNA (lnc-RNA) serving as a rearrangement partner with the PLAG1 gene. We reviewed the molecular characteristics of this entity and explored the potential role of LINC01606::PLAG1 in the tumorigenesis of pleomorphic adenoma.

Deep Learning Provides Rapid Screen for Breast Cancer Metastasis with Sentinel Lymph Nodes.

OBJECTIVE: Deep learning has been shown to be useful in detecting breast cancer metastases by analyzing whole slide images (WSI) of sentinel lymph nodes; however, it requires extensive analysis of all the lymph node slides. Our deep learning study attempts to provide a rapid screen for metastasis by analyzing only a small set of image patches to detect changes in tumor environment. METHODS: We designed a convolutional neural network to build a diagnostic model for metastasis detection. We obtained WSIs of Hematoxylin and Eosin-stained slides from 34 cases with equal distribution in positive/negative categories. Two WSIs were selected from each case for a total of 69 WSIs. From each WSI, 40 image patches (100x100 pixels) were obtained to yield 2720 image patches, from which 2160 (79%) were used for training, 240 (9%) for validation, and 320 (12%) for testing. Interobserver variation was also examined among 3 users. RESULTS: The test results showed excellent diagnostic results: accuracy (91.15%), sensitivity (77.92%), and specificity (92.09%). No significant variation in results was observed among the 3 observers. CONCLUSION: This preliminary study provided a proof of concept for conducting a rapid screen for metastasis rather than an exhaustive search for tumors in all fields of all sentinel lymph nodes.

EZH2 Cooperates with BRD4-NUT to Drive NUT Carcinoma Growth by Silencing Key Tumor Suppressor Genes.

NUT carcinoma is an aggressive carcinoma driven by the BRD4-NUT fusion oncoprotein, which activates chromatin to promote expression of progrowth genes. BET bromodomain inhibitors (BETi) are a promising treatment for NUT carcinoma that can impede BRD4-NUT's ability to activate genes, but the efficacy of BETi as monotherapy is limited. Here, we demonstrated that enhancer of zeste homolog 2 (EZH2), which silences genes through establishment of repressive chromatin, is a dependency in NUT carcinoma. Inhibition of EZH2 with the clinical compound tazemetostat potently blocked growth of NUT carcinoma cells. Epigenetic and transcriptomic analysis revealed that tazemetostat reversed the EZH2-specific H3K27me3 silencing mark and restored expression of multiple tumor suppressor genes while having no effect on key oncogenic BRD4-NUT-regulated genes. Indeed, H3K27me3 and H3K27ac domains were found to be mutually exclusive in NUT carcinoma cells. CDKN2A was identified as the only gene among all tazemetostat-derepressed genes to confer resistance to tazemetostat in a CRISPR-Cas9 screen. Combined inhibition of EZH2 and BET synergized to downregulate cell proliferation genes, resulting in more pronounced growth arrest and differentiation than either inhibitor alone. In preclinical models, combined tazemetostat and BETi synergistically blocked tumor growth and prolonged survival of NUT carcinoma-xenografted mice, with complete remission without relapse in one cohort. Identification of EZH2 as a dependency in NUT carcinoma substantiates the reliance of NUT carcinoma tumor cells on epigenetic dysregulation of functionally opposite, yet highly complementary, chromatin regulatory pathways to maintain NUT carcinoma growth. SIGNIFICANCE: Repression of tumor suppressor genes, including CDKN2A, by EZH2 provides a mechanistic rationale for combining EZH2 and BET inhibitors for the clinical treatment of NUT carcinoma. See related commentary by Kazansky and Kentsis, p. 3827.

EZH2 synergizes with BRD4-NUT to drive NUT carcinoma growth through silencing of key tumor suppressor genes.

NUT carcinoma (NC) is an aggressive carcinoma driven by the BRD4-NUT fusion oncoprotein, which activates chromatin to promote expression of pro-growth genes. BET bromodomain inhibitors (BETi) impede BRD4-NUT's ability to activate genes and are thus a promising treatment but limited as monotherapy. The role of gene repression in NC is unknown. Here, we demonstrate that EZH2, which silences genes through establishment of repressive chromatin, is a dependency in NC. Inhibition of EZH2 with the clinical compound tazemetostat (taz) potently blocked growth of NC cells. Epigenetic and transcriptomic analysis revealed that taz reversed the EZH2-specific H3K27me3 silencing mark, and restored expression of multiple tumor suppressor genes while having no effect on key oncogenic BRD4- NUT-regulated genes. CDKN2A was identified as the only gene amongst all taz-derepressed genes to confer resistance to taz in a CRISPR-Cas9 screen. Combined EZH2 inhibition and BET inhibition synergized to downregulate cell proliferation genes resulting in more pronounced growth arrest and differentiation than either inhibitor alone. In pre-clinical models, combined taz and BETi synergistically blocked growth and prolonged survival of NC-xenografted mice, with all mice cured in one cohort. STATEMENT OF SIGNIFICANCE: Identification of EZH2 as a dependency in NC substantiates the reliance of NC tumor cells on epigenetic dysregulation of functionally opposite, yet highly complementary chromatin regulatory pathways to maintain NC growth. In particular, repression of CDKN2A expression by EZH2 provides a mechanistic rationale for combining EZH2i with BETi for the clinical treatment of NC.

Infected Ruptured Parathyroid Cyst Presenting with Hypercalcemia and Airway Obstruction: A Case Report.

Parathyroid cysts (PC) are infrequently encountered and characterize less than 1% of all head and neck masses. When present, PCs may present as a palpable neck mass and lead to hypercalcemia and rarely respiratory depression. Furthermore, the diagnostics of PCs is difficult as they can masquerade as a thyroid or mediastinal mass given their proximity. PCs are theorized to be a progression of parathyroid adenomas and often routine surgical excision is sufficient for cure. To our knowledge, there is no documented report of a patient with an infected parathyroid cyst that led to severe dyspnea. This case describes our experience of a patient with an infected parathyroid cyst presenting as hypercalcemia and airway obstruction.

Oligometastatic Parathyroid Carcinoma Presenting as Neck Pain: A Case Report.

BACKGROUND: Parathyroid carcinoma (PC) is an exceedingly rare, slow-growing but progressive endocrine malignancy that represents a diagnostic and therapeutic challenge. Vertebral metastasis of PC is remarkable, with only 3 prior cases of spinal metastasis reported in the literature. CASE DESCRIPTION: A 62-year-old woman presented with 1 week of neck pain radiating down her right arm. Cervical x-ray revealed a lytic lesion of the C4 vertebral body. Lab work revealed hypercalcemia with an elevated parathyroid hormone level. Computed tomography and magnetic resonance imaging revealed frank destruction of the C4 vertebral body and pedicles by PC. She was treated with corpectomy, mass excision, anterior cervical discectomy and fusion, postoperative radiotherapy, and nonspecific inhibitors of active tumor pathways. Her symptoms resolved postoperatively, and she has remained negative for reoccurrence at 15-month follow-up. CONCLUSIONS: To the authors' knowledge, we report the first described cervical spine metastasis of PC. Additionally, we review the treatment of this rare neoplasm in an extremely rare location in the age of tumor sequencing and morphoproteomic analysis.

Invasive Lobular Carcinoma Mimicking Encapsulated Papillary Carcinoma with a Literature Review: A Rare Variant Detected Serendipitously.

Invasive lobular carcinoma with papillary features is a newly proposed variant which presents as a relatively well-circumscribed mass lesion with at least partial peripheral thickened fibrous capsule and central delicate fibrovascular cores, morphologically mimicking encapsulated papillary carcinoma or solid papillary carcinoma. There are only 5 cases described in literature. We here report an interesting example of invasive lobular carcinoma with papillary growth pattern surrounded by a thick fibrous capsule, mimicking encapsulated papillary carcinoma (EPC). The lobular nature of the tumor was confirmed by the absence of membranous expression of E-cadherin and p120 catenin. The lobular cytological features are subtle in this variant and may be overlooked. Differentiation of this variant from papillary carcinomas is crucial for correct tumor categorization, staging and most importantly, proper treatment.

NUT Carcinoma: Clinicopathologic Features, Molecular Genetics and Epigenetics.

Nuclear protein in testis (NUT) carcinoma is a rare, highly aggressive, poorly differentiated carcinoma occurring mostly in adolescents and young adults. This tumor usually arises from the midline structures of the thorax, head, and neck, and exhibits variable degrees of squamous differentiation. NUT carcinoma is defined by the presence of a NUTM1 (15q14) rearrangement with multiple other genes. In about 70-80% of the cases, NUTM1 is involved in a balanced translocation with the BRD4 gene (19p13.12), leading to a BRD4-NUTM1 fusion oncogene. Other variant rearrangements include BRD3-NUTM1 fusion (~15-20%) and NSD3-NUTM1 fusion (~6%), among others. The diagnosis of NUT carcinoma requires the detection of nuclear expression of the NUT protein by immunohistochemistry. Additional methods for diagnosis include the detection of a NUTM1 rearrangement by fluorescence in situ hybridization or by reverse transcriptase PCR. NUT carcinoma is usually underrecognized due to its rarity and lack of characteristic histological features. Therefore, the goal of this review is to provide relevant recent information regarding the clinicopathologic features of NUT carcinoma, the role of the multiple NUTM1 gene rearrangements in carcinogenesis, and the impact of understanding these underlying molecular mechanisms that may result in the development of possible novel targeted therapies.

Massive macroglossia, a rare side effect of COVID-19: clinical, histologic, and genomic findings in COVID-19-positive versus COVID-19-negative patients.

PURPOSE: The primary purpose of this study is to identify if there is an underlying genetic predisposition for COVID-related macroglossia and if this susceptibility is higher among individuals of African heritage. Secondary objectives include determining if genetic testing of COVID-infected patients who are intubated and prone could identify patients with higher susceptibility to the development of macroglossia. METHODS: A retrospective chart review was completed for each patient, and prospectively, genetic and histopathologic analyses were completed. Whole-exome sequencing was completed on two patients; immunohistochemistry was completed on the COVID-positive tissue samples. RESULTS: Histopathology of the COVID-positive patient revealed significant peri-lymphocytic infiltrate, which was absent in the COVID-negative patient. Immunohistochemistry confirmed the presence of immune cells. Results from the whole-exome sequencing were inconclusive. CONCLUSION: The findings of this study are consistent with others that have observed a lymphocytic infiltrate in the organs of patients infected with SARS-CoV-2. On histology, IHC highlighted a CD45 + predominance, indicating that a robust immune response is present in the tissues. The pathobiology of this phenomenon and its role in the development and/or persistence of massive macroglossia requires further study.

Cyclin D1 expression in Rosai-Dorfman disease: a near-constant finding that is not invariably associated with mitogen-activated protein kinase/extracellular signal-regulated kinase pathway activation.

Activating mutations in the mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) pathway have been shown in nearly half of the cases of Rosai-Dorfman disease (RDD). Cyclin D1, a key cell cycle regulator, constitutes a major downstream target of the MAPK/ERK pathway. In this study, we aim to further understand the pathogenesis of RDD by assessing the lesional histiocytes for cyclin D1, p-ERK, Ki-67, and BCL-2 by immunohistochemistry. We assessed 35 samples of RDD and a control group of histiocyte-rich reactive lesions. Cyclin D1 was expressed in about 90% of cases of RDD. Cyclin D1 was positive in 25-95% (median, 85%) of lesional histiocytes, was moderately/strongly expressed in 97% of cyclin D1-positive cases, and was significantly higher than in control specimens. p-ERK was positive in 16 of 30 (53%) cases of RDD and was negative in all controls. All p-ERK-positive RDD cases had concurrent cyclin D1 expression, whereas more than a third of cyclin D1-positive cases were negative for p-ERK. Ki-67 was low in RDD (median, 3%). BCL-2 was positive in lesional histiocytes in nine of 10 RDD cases assessed. Overall, these findings point to unexpected, potential roles of these molecules in the pathogenesis of RDD. Overexpression of cyclin D1 in the absence of ERK phosphorylation in a subset of RDD cases opens the possibility of oncogenic mechanisms bypassing ERK and supports the notion that cyclin D1 overexpression in RDD is multifactorial. Moreover, the observed lack of correlation between cyclin D1 with Ki-67 proliferative index suggests that prosurvival actions of cyclin D1 are, at least in part, cell cycle independent. Finally, expression of BCL-2 and the low Ki-67 index suggest that RDD might be driven by antiapoptotic rather than proproliferative oncogenic mechanisms.

Sinonasal Hamartomas: From Nasal Chondromesenchymal Hamartoma to Respiratory Epithelial Adenomatoid Hamartoma. Report of six Cases and Review of the Literature.

Sinonasal hamartomas are uncommon lesions of nasal and sinus cavities. Based on indigenous cellular components and characteristic histologic features, they are further classified into four entities: respiratory epithelial adenomatoid hamartoma (REAH), seromucinous hamartoma (SH), chondro-osseous and respiratory epithelial hamartoma (CORE), and nasal chondromesenchymal hamartoma (NCH). REAH, SH, and CORE are seen in adult patients, while NCH predominantly occurs in newborns and infants. Morphologically REAH and SH are composed of respiratory epithelium and seromucinous glands, CORE is related to REAH but with additional feature of chondroid and/or osseous tissue, and NCH is composed of chondroid and stromal elements but devoid of epithelial component. All four lesions can present as sinonasal mass lesions and with associated obstructive symptoms. Given the rarity of these lesions, diagnosis can be challenging, especially in unusual clinical scenario. In this study, we report six cases of sinonasal hamartoma, including one case of NCH, one case of CORE, two cases of SH, and two cases of REAH. All cases were from adult patients including four men and two women. We also review the literature of the clinical and pathologic features of these rare lesions.

Cystic Encapsulated Papillary Carcinoma in the Male Breast: An Unusual Feature With a Diagnostic Challenge.

Papillary carcinoma in the male breast is uncommon. Here, we report a case of a large encapsulated papillary carcinoma (EPC) in a 62-year-old male. The patient presented with a left breast mass of 1-year duration and bloody nipple discharge for several days. Mammography and breast ultrasonography showed a large left breast mass. The initial biopsy demonstrated fat necrosis with acute and chronic inflammation only. Due to clinical suspicion, a repeat biopsy was performed and revealed scant fragments of papillary carcinoma in a background of inflammation. The patient underwent left total mastectomy. Grossly, the breast contained a 9.0 cm entirely cystic lesion lined by a hemorrhagic thick fibrotic wall. No solid area was identified in the cyst. The entire cyst wall was examined under microscopy; only a few sections with papillary carcinoma were identified. The lesion was confined to the cyst wall; so, a diagnosis of EPC was made. Compared to the previously reported EPC cases of male breast, the lesion of this case was unusually cystic, which making the diagnosis challenging. Therefore, awareness of this unusual feature, repeat biopsy when the pathology result is discordant, and extensive sampling of the lesion are essential for making the correct diagnosis and guiding patient management.

NUT Carcinoma of the Submandibular Gland: A Case at This Uncommon Site with Review of the Literature.

Nuclear protein in testis (NUT) carcinoma is a rare, highly aggressive, undifferentiated carcinoma that harbors a characteristic rearrangement of the NUTM1 gene. The majority arise in adolescents and young adults especially from the midline structures of the thorax, head, and neck. Until the present, there have only been three reported cases of NUT carcinoma of the submandibular gland, two of which were reported in children and another one in an adult from Korea. Here, we report the first case of NUT carcinoma arising in the submandibular gland of an adult female in the United States, representing the fourth case worldwide. A fine needle aspiration and biopsy was performed, and the diagnosis was confirmed by NUT immunohistochemical staining and fusion of the BRD4 (19p13.12) and NUTM1 (15q14) gene loci by fluorescence in-situ hybridization on the resection specimen. Salivary gland is an unusual site for NUT carcinoma and is rarely described in submandibular gland. We reviewed the clinicopathologic features of this entity at this site along with role of NUTM1 gene rearrangements in NUT tumorigenesis.

Spindle Cell Squamous Cell Carcinoma of the Larynx with Malignant Osteoid Differentiation: A Case Report and Review of Literature.

Spindle cell squamous cell carcinoma of the larynx is a rare, aggressive variant of squamous cell carcinoma. It comprises 0.6-1.5% of all laryngeal cancers. Heterologous mesenchymal differentiation as bone, cartilage, and muscle is uncommon, especially malignant osteoid differentiation, as a handful of cases reported in the literature. We present the case of a 66-year-old male active smoker who presented with dysphonia and acute stridor. On examination, a 2.0 cm pedunculated, broad-base, glottic mass involving the left true vocal cord and ventricle was noted, with extension to the anterior commissure causing a narrowing of the airway. The patient underwent localized left vocal cordectomy. The histopathologic and immunohistochemical findings were consistent with spindle cell carcinoma with malignant osteoid differentiation. The patient is alive, status-post adjuvant five cycles of cisplatin therapy, with no recurrence at 18 months of follow-up. We discuss a literature review of this rare entity with either malignant osteoid or osteocartilaginous differentiation.