Next-generation sequencing of salivary high-grade neuroendocrine carcinomas identifies alterations in RB1 and the mTOR pathway

Metastatic Neuroendocrine Tumors to Parotid Gland: Where Do They Come From?

Background. Metastasis to parotid gland occurs mostly from skin cancers of the head and neck region. Metastatic neuroendocrine tumors to the parotid gland are rare and not well studied so far. In this study, we undertook a retrospective review of secondary neuroendocrine tumors of the parotid diagnosed in our institution. The most common entities, primary tumor locations, their clinical presentations and histopathological features were analyzed. Methods. Cases of secondary neuroendocrine tumors to parotid diagnosed from August 1995 to Jan 2021 were retrieved from our institution's pathology databases, and their clinicopathological features were reviewed. Results. About 29% (120 of 420 cases) of parotid neoplasms were malignant, including 70 cases of parotid primary malignant tumors and 50 cases of metastases to parotid glands. Among metastatic tumors to the parotid glands, squamous cell carcinoma and melanoma of the head and neck region together accounted for about 78% of the cases. Only 11 of 50 metastatic tumors to the parotid were neuroendocrine carcinomas (22%). The most common primaries were poorly differentiated neuroendocrine carcinoma of lung (5 of 11 cases), including 4 cases of small cell carcinoma and one case of large cell neuroendocrine carcinoma. The second most common secondary tumor was Merkel cell carcinoma (4 of 11 cases, 36%) including one case of direct invasion from overlying skin. Medullary carcinoma of the thyroid comprised the rest of the metastases to the parotid (2 of 11 cases, 18%). Conclusion. Our results show that metastatic neuroendocrine carcinomas to the parotid gland account for about 22% of all metastatic tumors to the organ. Lung is the most common primary neuroendocrine carcinoma location. It is not uncommon for metastatic neuroendocrine carcinoma to present as the first sign of systemic clinical manifestation. Merkel cell carcinoma is the second most common entity that metastasizes to parotid, followed by medullary carcinoma of the thyroid.

Genomics of High-Grade Neuroendocrine Neoplasms: Well-Differentiated Neuroendocrine Tumor with High-Grade Features (G3 NET) and Neuroendocrine Carcinomas (NEC) of Various Anatomic Sites

High-grade neuroendocrine neoplasms (HG-NENs) are clinically aggressive diseases, the classification of which has recently been redefined. They now include both poorly differentiated NENs (neuroendocrine carcinoma, NECs) and high proliferating well-differentiated NENs (called grade 3 neuroendocrine tumors, G3 NETs, in the digestive system). In the last decade, the "molecular revolution" that has affected all fields of medical oncology has also shed light in the understanding of HG NENs heterogeneity and has provided new diagnostic and therapeutic tools, useful in the management of these malignancies. Considering the kaleidoscopic aspects of HG NENs in various anatomical sites, this review systematically addresses the genomic landscape of such neoplasm throughout the more common thoracic and digestive locations, as well as it will consider other rare but not exceptional primary sites, including the skin, the head and neck, and the urogenital system. The revision of the available literature will then be oriented to understand the translational relevance of molecular data, by analyzing conceptual issues, clinicopathological correlations, and unmet needs in this field.

Proceedings of the NASHNP Companion Meeting, March 18th, 2018, Vancouver, BC, Canada: Salivary Neuroendocrine Carcinoma-An Overview of a Rare Disease with an Emphasis on Determining Tumor Origin

Salivary neuroendocrine carcinomas are rare and the overwhelming majority is high-grade. The parotid gland is the most commonly involved site followed by the submandibular gland. Most arise de novo but rare examples occurring as a high-grade transformation of another type of salivary gland neoplasm exist. There is significant morphologic and immunophenotypic overlap with neuroendocrine carcinomas of other sites, especially the skin. Like cutaneous neuroendocrine (or Merkel cell) carcinomas, approximately three-fourths are cytokeratin 20 positive. Cytokeratin 20 positive salivary neuroendocrine carcinomas are often referred to as being of the 'Merkel cell type' since most other non-cutaneous neuroendocrine carcinomas are cytokeratin 20 negative. Salivary neuroendocrine carcinomas may be challenging to separate from Merkel cell carcinomas of the head and neck on pathologic grounds because the latter often metastasize to the parotid gland. Clinical history is often relied upon to separate primary salivary tumors from cutaneous metastases but may not be helpful in all cases. Here we review the clinical, pathologic and molecular features of salivary neuroendocrine carcinomas focusing on high-grade major salivary gland tumors. The difficulty in separating salivary tumors from metastatic Merkel cell carcinoma will be highlighted.

Somatic Variants in the Human Lens Epithelium: A Preliminary Assessment

Purpose

We hypothesize that somatic mutations accumulate in cells of the human lens and may contribute to the development of cortical or posterior sub-capsular cataracts. Here, we used a Next-generation sequencing (NGS) strategy to screen for low-allelic frequency variants in DNA extracted from human lens epithelial samples.

Methods

Next-Generation sequencing of 151 cancer-related genes (WUCaMP2 panel) was performed on DNA extracted from post-mortem or surgical specimens obtained from 24 individuals. Usually, pairwise comparisons were made between two or more ocular samples from the same individual, allowing putative somatic variants detected in lens samples to be differentiated from germline variants.

Results

Use of a targeted hybridization approach enabled high sequence coverage (>1000-fold) of the WUCaMP2 genes. In addition to high-frequency variants (corresponding to homozygous or heterozygous SNPs and Indels), somatic variants with allelic frequencies of 1-4% were detected in the lens epithelial samples. The presence of one such variant, a T > C point substitution at position 32907082 in BRCA2, was verified subsequently using droplet digital PCR.

Conclusions

Low-allelic fraction variants are present in the human lens epithelium, at frequencies consistent with the presence of millimeter-sized clones.

p16 overexpression in high-grade neuroendocrine carcinomas of the head and neck: potential diagnostic pitfall with HPV-related carcinomas

High-grade neuroendocrine carcinomas (HGNECs) of the head and neck have the morphological appearance of undifferentiated carcinomas and could be histologically similar to human papillomavirus (HPV)-associated non-keratinizing squamous cell carcinomas of the head and neck. The aim of the study is to characterize histologically, immunohistochemically, and virologically these unusual neoplasms. Nineteen HGNECs of the head and neck (1 oropharyngeal, 5 sinonasal, 7 of the larynx, and 6 of the parotid gland) were reviewed and analyzed with a immunohistochemical panel, with special emphasis on cell cycle proteins. The tumors were tested for HPV by in situ hybridization (GenPoint HPV, Dako) and PCR (SPF10-DEIA-LiPA25). Merkel cell polyomavirus was studied using the antibody CM2B4. Fifteen HGNEC were of small cell and 4 of large cell type. Most of the tumors (14/19, 73.7 %), including all the pure small cell carcinomas, showed a strong and diffuse positive staining for p16. Eleven of them (78.5 %) had Rb loss and a low or absent cyclin D1 expression. All cases were negative for HPV and polyomavirus. Most patients were smokers, diagnosed at advanced stages of the disease, and had a poor outcome, with a 5-year survival of 18 %. In conclusion, HGNECs of the head and neck are infrequently related to HPV infection, but usually show strong, diffuse positive p16 immunostaining due to Rb pathway dysregulation. Awareness of this immunohistochemical pattern of expression may avoid a potential diagnostic pitfall with HPV-associated non-keratinizing squamous cell carcinomas, which have a better prognosis.