Faculty Bibliography

Myopericytomas are uncommon tumors defined by their round to spindle shaped cells often arranged in a concentric pattern of perivascular growth. They are typically well-circumscribed, nodular, slow-growing lesions that occur in the soft tissue of the extremities. Here, we present a 30-year-old female with a 2.4 cm myopericytoma occurring in the deep lobe of the parotid gland. The diagnosis was made with detailed histopathologic and immunohistochemical findings and positive identification of the specific mutation for PDGFRβ p.Asp666Lys by next generation sequencing (NGS). This is the first case report of a parotid myopericytoma with a genetic testing that shows a particular mutation that has been linked to myopericytomatosis.

Oral squamous cell carcinoma (SCC) pain is more prevalent and severe than pain generated by any other form of cancer. We previously showed that protease-activated receptor-2 (PAR₂) contributes to oral SCC pain. Cathepsin S is a lysosomal cysteine protease released during injury and disease that can activate PAR₂. We report here a role for cathepsin S in PAR₂-dependent cancer pain. We report that cathepsin S was more active in human oral SCC than matched normal tissue, and in an orthotopic xenograft tongue cancer model than normal tongue. The multiplex immunolocalization of cathepsin S in human oral cancers suggests that carcinoma and macrophages generate cathepsin S in the oral cancer microenvironment. After cheek or paw injection, cathepsin S evoked nociception in wild-type mice but not in mice lacking PAR₂ in Na_v1.8-positive neurons (Par₂Na_v1.8), nor in mice treated with LY3000328 or an endogenous cathepsin S inhibitor (cystatin C). The human oral SCC cell line (HSC-3) with homozygous deletion of the gene for cathepsin S (CTSS) with CRISPR/Cas9 provoked significantly less mechanical allodynia and thermal hyperalgesia, as did those treated with LY3000328, compared to the control cancer mice. Our results indicate that cathepsin S is activated in oral SCC, and that cathepsin S contributes to cancer pain through PAR₂ on neurons.

Introduction: TERT promoter mutations in thyroid carcinoma suggest worse prognosis based on findings of a small number of studies. Additionally, pathologic features and clinical behavior of indeterminate thyroid nodules (ITN) with TERT promoter mutations remain less studied. Our study aims to explore the clinicopathologic features of ITN with TERT promoter mutations.
Material(s) and Method(s): A search conducted in our electronic medical record between 2015-2018 identified 18 cases with indeterminate thyroid fine-needle aspiration (FNA) cytology (Bethesda Class III, IV, and V) and a TERT mutation on molecular testing. 17 patients underwent thyroidectomy and were the subjects of this study.
Result(s): The mean age was 65 (range 38-83) with a female to male ratio of 9:8. The FNA Bethesda diagnoses were Class III in 9, IV in 8, and V in 1. Majority of patients who underwent thyroidectomy had malignant nodules (14,78%). Thyroidectomy diagnoses included classic PTC (5,29%), FVPTC (5,29%), follicular variant of papillary carcinoma (3,17%), poorly differentiated thyroid carcinoma (1, 6%), follicular adenoma (2,11%) and NIFTP (1,6%). Additional alterations were present in 11 cases, including NRAS(6), KRAS(2), and BRAF V600E (3). Of three cases with concurrent BRAF V600E mutation, two were metastatic, and one had tall cell features. Of two follicular adenoma cases, one had a concomitant NRAS mutation, and the other displayed negative results on Afirma testing. Malignant cases tended to occur in older patients, the majority exhibited follicular architecture, frequent oncocytic morphology, and higher pathologic stage (pT3 in 92%, pT2 in 8%).
Conclusion(s): Most TERT promoter mutations in ITN cytology are associated with high risk of malignancy and these malignancies are associated with unfavorable features such as advanced stage, capsular/vascular invasion, and metastatic disease. Few TERT promoter mutations have a benign outcome. Further studies on ITNs with TERT mutations are needed to determine the optimal management of these nodules.
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IDH2 R172 mutations occur in sinonasal undifferentiated carcinoma (SNUC), large-cell neuroendocrine carcinoma (LCNEC), sinonasal adenocarcinomas, and olfactory neuroblastoma (ONB). We performed a clinical, pathologic, and genetic/epigenetic analysis of a large IDH2-mutated sinonasal tumor cohort to explore their distinct features. A total 165 sinonasal/skull base tumors included 40 IDH2 mutants studied by light microscopy, immunohistochemistry, and genome-wide DNA methylation, and 125 IDH2 wild-type tumors used for comparison. Methylation profiles were analyzed by unsupervised hierarchical clustering, t-distributed stochastic neighbor embedding dimensionality reduction and assessed for copy number alterations (CNA). Thirty-nine histologically assessable cases included 25 (64.1%) SNUC, 8 (20.5%) LCNEC, 2 (5.1%) poorly differentiated adenocarcinomas, 1 (2.7%) ONB, and 3 (7.7%) IDH2-mutated tumors with ONB features. All cases were high-grade showing necrosis (82.4%), prominent nucleoli (88.9%), and median 21 mitoses/10 HPFs. AE1/AE3 and/or CAM 5.2 were positive in all and insulinoma-associated protein 1 (INSM1) in 80% cases. All IDH2 mutants formed one distinct group by t-distributed stochastic neighbor embedding dimensionality reduction separating from all IDH2 wild-type tumors. There was no correlation between methylation clusters and histopathologic diagnoses. Recurrent CNA included 1q gain (79.3%), 17p loss (75.9%), and 17q gain (58.6%). No CNA differences were observed between SNUC and LCNEC. IDH2 mutants showed better disease-specific survival than SMARCB1-deficient (P=0.027) and IDH2 wild-type carcinomas overall (P=0.042). IDH2-mutated sinonasal tumors are remarkably homogeneous at the molecular level and distinct from IDH2 wild-type sinonasal malignancies. Biology of IDH2-mutated sinonasal tumors might be primarily defined by their unique molecular fingerprint rather than by their respective histopathologic diagnoses.

Bodies have continuous reticular networks, comprising collagens, elastin, glycosaminoglycans, and other extracellular matrix components, through all tissues and organs. Fibrous coverings of nerves and blood vessels create structural continuity beyond organ boundaries. We recently validated fluid flow through human fibrous tissues, though whether these interstitial spaces are continuous through the body or discontinuous, confined within individual organs, remains unclear. Here we show evidence for continuity of interstitial spaces using two approaches. Non-biological particles (tattoo pigment, colloidal silver) were tracked within colon and skin interstitial spaces and into adjacent fascia. Hyaluronic acid, a macromolecular component of interstitial spaces, was also visualized. Both techniques demonstrate interstitial continuity within and between organs including within perineurium and vascular adventitia traversing organs and the spaces between them. We suggest that there is a body-wide network of fluid-filled interstitial spaces that has significant implications for molecular signaling, cell trafficking, and the spread of malignant and infectious disease.

Background: Thyroseq next-generation sequencing assay and Afirma gene expression classifier (GEC) are used to risk-stratify thyroid nodules with indeterminate cytology: Bethesda III (atypia of undetermined significance, AUS/FLUS) and IV (suspicious for follicular neoplasm, SFN). In this study, we performed a paired comparison of both tests on the same group of indeterminate thyroid nodules with surgical followup.
Design(s): Of 645 AUS/FLUS/SFN cases with both molecular testing and surgical resection in 2014-2017, 40 cases had both Thyroseq (v2) and Afirma GEC performed on the same specimen. Cross-tabulations and ROC curves were created. McNemar tests were done to compare the performance of Thyroseq versus Afirma. The diagnostic performance of combined results were also examined: the combined result was called positive only if both Thyroseq and Afirma were positive/suspicious. Non-invasive follicular thyroid with papillary like nuclear features (NIFTP) on surgical resections was defined as ?positive.? Results: 20/40 (50%) cases were ?positive? on surgical pathology: 8 papillary thyroid carcinoma (PTC), 11 NIFTP, and 1 follicular carcinoma. Thyroseq and Afirma both showed high sensitivity and low specificity in diagnosing malignancy in indeterminate thyroid nodules. Next, the results of both tests were combined. The overall accuracy of combined testing was higher than either test alone (Figure 1). Compared to Afirma alone, the combined test had significantly higher specificity (30% vs 70%, p<0.05, Table 1), while the sensitivity declined from 90% to 75% (p=0.25, Table 1). Compared to Thyroseq alone, there was no significant difference in specificity (45% vs 70% p=0.06) or sensitivity (80% vs 75%, p=1.00, Table 1). Positive predictive value (PPV) improved compared to either test alone. Negative predictive value (NPV) improved compared to Thyroseq alone, and declined only slightly compared to Afirma alone.
Conclusion(s): Molecular testing of cytologically indeterminate thyroid nodules helps determine the extent of surgery. Low diagnostic performance metrics may limit the utility of molecular studies in distinguishing benign from malignant thyroid lesions. Our results show that the combined results of Thyroseq and Afirma improved the specificity and overall accuracy of molecular testing, and provided additional value in the surgical management of patients with indeterminate thyroid nodules. To the best of our knowledge, this is the first study that compares the performance of these two molecular tests on the same thyroid nodules