Deficiency in Ever2 does not increase susceptibility of mice to pathogenesis by the mouse papillomavirus, MmuPV1.

Epidermodysplasia verruciformis (EV) is a rare genetic skin disorder that is characterized by the development of papillomavirus-induced skin lesions that can progress to squamous cell carcinoma (SCC). Certain high-risk, cutaneous ß-genus human papillomaviruses (ß-HPVs), in particular HPV5 and HPV8, are associated with inducing EV in individuals who have a homozygous mutation in one of three genes tied to this disease: EVER1, EVER2, or CIB1. EVER1 and EVER2 are also known as TMC6 and TMC8, respectively. Little is known about the biochemical activities of EVER gene products or their roles in facilitating EV in conjunction with ß-HPV infection. To investigate the potential effect of EVER genes on papillomavirus infection, we pursued in vivo infection studies by infecting Ever2-null mice with mouse papillomavirus (MmuPV1). MmuPV1 shares characteristics with ß-HPVs including similar genome organization, shared molecular activities of their early, E6 and E7, oncoproteins, the lack of a viral E5 gene, and the capacity to cause skin lesions that can progress to SCC. MmuPV1 infections were conducted both in the presence and absence of UVB irradiation, which is known to increase the risk of MmuPV1-induced pathogenesis. Infection with MmuPV1 induced skin lesions in both wild-type and Ever2-null mice with and without UVB. Many lesions in both genotypes progressed to malignancy, and the disease severity did not differ between Ever2-null and wild-type mice. However, somewhat surprisingly, lesion growth and viral transcription was decreased, and lesion regression was increased in Ever2-null mice compared with wild-type mice. These studies demonstrate that Ever2-null mice infected with MmuPV1 do not exhibit the same phenotype as human EV patients infected with ß-HPVs.IMPORTANCEHumans with homozygous mutations in the EVER2 gene develop epidermodysplasia verruciformis (EV), a disease characterized by predisposition to persistent ß-genus human papillomavirus (ß-HPV) skin infections, which can progress to skin cancer. To investigate how EVER2 confers protection from papillomaviruses, we infected the skin of homozygous Ever2-null mice with mouse papillomavirus MmuPV1. Like in humans with EV, infected Ever2-null mice developed skin lesions that could progress to cancer. Unlike in humans with EV, lesions in these Ever2-null mice grew more slowly and regressed more frequently than in wild-type mice. MmuPV1 transcription was higher in wild-type mice than in Ever2-null mice, indicating that mouse EVER2 does not confer protection from papillomaviruses. These findings suggest that there are functional differences between MmuPV1 and ß-HPVs and/or between mouse and human EVER2.

MmuPV1 E7's interaction with PTPN14 delays Epithelial differentiation and contributes to virus-induced skin disease.

Human papillomaviruses (HPVs) contribute to approximately 5% of all human cancers. Species-specific barriers limit the ability to study HPV pathogenesis in animal models. Murine papillomavirus (MmuPV1) provides a powerful tool to study the roles of papillomavirus genes in pathogenesis arising from a natural infection. We previously identified Protein Tyrosine Phosphatase Non-Receptor Type 14 (PTPN14), a tumor suppressor targeted by HPV E7 proteins, as a putative cellular target of MmuPV1 E7. Here, we confirmed the MmuPV1 E7-PTPN14 interaction. Based on the published structure of the HPV18 E7/PTPN14 complex, we generated a MmuPV1 E7 mutant, E7K81S, that was defective for binding PTPN14. Wild-type (WT) and E7K81S mutant viral genomes replicated as extrachromosomal circular DNAs to comparable levels in mouse keratinocytes. E7K81S mutant virus (E7K81S MmuPV1) was generated and used to infect FoxN/Nude mice. E7K81S MmuPV1 caused neoplastic lesions at a frequency similar to that of WT MmuPV1, but the lesions arose later and were smaller than WT-induced lesions. The E7K81S MmuPV1-induced lesions also had a trend towards a less severe grade of neoplastic disease. In the lesions, E7K81S MmuPV1 supported the late (productive) stage of the viral life cycle and promoted E2F activity and cellular DNA synthesis in suprabasal epithelial cells to similar degrees as WT MmuPV1. There was a similar frequency of lateral spread of infections among mice infected with E7K81S or WT MmuPV1. Compared to WT MmuPV1-induced lesions, E7K81S MmuPV1-induced lesions had a significant expansion of cells expressing differentiation markers, Keratin 10 and Involucrin. We conclude that an intact PTPN14 binding site is necessary for MmuPV1 E7's ability to contribute to papillomavirus-induced pathogenesis and this correlates with MmuPV1 E7 causing a delay in epithelial differentiation, which is a hallmark of papillomavirus-induced neoplasia.

POU2AF3-rearranged sarcomas: A novel tumor defined by fusions of EWSR1 or FUS to a gene formerly designated COLCA2.

Gene fusions involving EWSR1 or FUS as the 5' partner have been reported in a diverse array of sarcomas. Here, we characterize the histopathology and genomics of six tumors harboring a gene fusion between EWSR1 or FUS and POU2AF3, an understudied, putative colorectal cancer predisposition gene. Striking morphologic features reminiscent of synovial sarcoma were observed including a biphasic appearance with variable fusiform to epithelioid cytomorphology and staghorn-type vasculature. RNA sequencing demonstrated variable breakpoints in EWSR1/FUS along with similar breakpoints in POU2AF3 that encompassed a 3' portion of this gene. For cases in which additional information was available, the behavior of these neoplasms was aggressive with local spread and/or distant metastases. Although further studies are needed to confirm the functional significance of our findings, POU2AF3 fusions to EWSR1 or FUS may define a novel type of POU2AF3-rearranged sarcomas with aggressive, malignant behavior.

Genetic characterisation of adult primary pleomorphic uterine rhabdomyosarcoma and comparison with uterine carcinosarcoma.

AIMS: To characterise the genetic alterations in adult primary uterine rhabdomyosarcomas (uRMSs) and to investigate whether these tumours are genetically distinct from uterine carcinosarcomas (UCSs). METHODS AND RESULTS: Three tumours originally diagnosed as primary adult pleomorphic uRMS were subjected to massively parallel sequencing targeting 468 cancer-related genes and RNA-sequencing. Mutational profiles were compared with those of UCSs (n = 57) obtained from The Cancer Genome Atlas. Sequencing data analyses were performed using validated bioinformatic approaches. Pathogenic TP53 mutations and high levels of genomic instability were detected in the three cases. uRMS1 harboured a likely pathogenic YTHDF2-FOXR1 fusion. uRMS2 harboured a PPP2R1A hotspot mutation and amplification of multiple genes, including WHSC1L1, FGFR1, MDM2, and CCNE1, whereas uRMS3 harboured an FBXW7 hotspot mutation and an ANKRD11 homozygous deletion. Hierarchical clustering of somatic mutations and copy number alterations revealed that these tumours initially diagnosed as pleomorphic uRMSs and UCSs were similar. Subsequent comprehensive pathological re-review of the three uRMSs revealed previously unidentified minute pan-cytokeratin-positive atypical glands in one case (uRMS3), favouring its reclassification as UCS with extensive rhabdomyosarcomatous overgrowth. CONCLUSIONS: Adult pleomorphic uRMSs harbour TP53 mutations and high levels of copy number alterations. Our findings underscore the challenge in discriminating between uRMS and UCS with rhabdomyosarcomatous differentiation.

PAX8-positive, Cytokeratin-positive Intra-abdominal Ewing Sarcoma Masquerading as a Mullerian Carcinoma in a Postmenopausal Female.

Extraskeletal Ewing sarcoma presenting as intra-abdominal or pelvic disease in adult female patients is very rare and may lead to diagnostic difficulty due to clinical and histologic overlap with Mullerian adenocarcinomas, which are far more common. We report a case of an intra-abdominal Ewing sarcoma in a postmenopausal female patient whose clinical and radiological presentation closely resembled that of peritoneal carcinomatosis. Biopsy of an omental nodule revealed numerous histologic features suggestive of a Mullerian carcinoma, including gland-like rosettes, strong, diffuse PAX8 immunoreactivity and cytokeratin expression. After excluding other differential diagnostic considerations, the possibility that this might represent an intra-abdominal Ewing sarcoma was entertained. Reverse transcriptase polymerase chain reaction testing demonstrated the presence of an EWSR1-ERG fusion transcript, confirming the diagnosis. The differential diagnostic considerations when dealing with this unusual clinical scenario and the uncommon yet important pitfall of PAX8 immunoreactivity in Ewing sarcoma are discussed.

The evolving concept of cancer stem-like cells in thyroid cancer and other solid tumors.

The cancer stem-like cell (CSC) hypothesis postulates that a small population of cells in a cancer has self-renewal and clonal tumor initiation properties. These cells are responsible for tumor initiation, growth, recurrence and for resistance to chemotherapy and radiation therapy. CSCs can be characterized using markers such as SSEA-1, SSEA-4, CD44, CD24, ALDEFLUOR and others. CSCs form spheres when they are cultured in serum-free condition in low attachment plates and can generate tumors when injected into immune-deficient mice. During epithelial to mesenchymal transition (EMT), cells lose cellular adhesion and polarity and acquire an invasive phenotype. Recent studies have established a relationship between EMT and increased numbers of CSCs in some solid malignancies. Non-coding RNAs such as microRNAs and long non-coding RNAs (lncRNAs) have been shown to have important roles during EMT and some of these molecules also have regulatory roles in the proliferation of CSCs. Specific lncRNAs enhanced cell migration and invasion in breast carcinomas, which was associated with the generation of stem cell properties. The tumor microenvironment of CSCs also has an important role in tumor progression. Recent studies have shown that the interaction between tumor cells and the local microenvironment at the metastatic site leads to the development of premetastatic niche(s) and allows for the proliferation of the metastatic cells during colonization. The role of exosomes in the microenvironment during the EMT program is currently a major area of research. This review examines CSCs and the relationship between EMT and CSCs in solid tumors with emphasis on thyroid CSCs. The role of non-coding RNAs and of the microenvironment in EMT and in tumor progression are also examined. This review also highlights the growing number of studies that show the close association of EMT and CSCs and the role of exosomes and other elements of the tissue microenvironment in CSC metastasis. A better understanding of these mechanisms will lead to more effective targeting of primary and metastatic malignancies.

AKT activity is elevated in aggressive thyroid neoplasms where it promotes proliferation and invasion.

The PI3K/AKT/mTOR signaling pathway controls major cellular processes such as cell growth, proliferation and survival. Stimulation of this pathway leads to AKT phosphorylation and activation, resulting in phosphorylation of mTOR and myriad other targets. AKT upregulation has been implicated in thyroid cancer pathogenesis and is a candidate treatment target for patients with advanced disease that has not responded to traditional therapies. Here we evaluate a large series of benign and malignant thyroid tumors for AKT activity and intracellular distribution. We also deplete AKT from multiple thyroid cancer cell lines, including putative cancer stem cell lines, and measure the effect on proliferation and invasion in vitro. We show that active AKT has a predominantly nuclear distribution and its expression is highest in anaplastic thyroid carcinomas and papillary thyroid carcinomas, including encapsulated and invasive follicular variants. Depletion of AKT in thyroid carcinoma cell lines led to greatly reduced proliferative capacity and resulted in a reduction of invasive potential. A reduction in invasion was also observed in the cancer stem cell compartment. Targeting AKT activity in the clinical setting may slow the growth and spread of aggressive thyroid neoplasms, and target the tumor stem cell compartment.

Synchronous Presentation of Renal Cell Carcinoma and Hodgkin Lymphoma in an Adolescent.

BACKGROUND: Coincidence of renal cell carcinoma (RCC) and hematologic malignancies has been reported in adults but not in children. OBSERVATION: We report a case of a 16-year-old girl in whom RCC was incidentally discovered on the computed tomography scan that was performed to stage her underlying Hodgkin lymphoma. Analysis of constitutional cytogenetics for common genetic aberrations that predispose to RCC did not reveal any mutations or genetic variations. However, cytogenetics on the RCC tumor demonstrated a rare reciprocal translocation between chromosomes 6 and 11, t(6;11)(p21;q12). After undergoing partial nephrectomy with regional lymphadenectomy and treatment with multiagent chemotherapy, patient is cancer-free, now 33 months from end of therapy. CONCLUSIONS: This case highlights the importance for histologic confirmation of a renal mass when concurrently discovered during the diagnostic evaluation of other malignancies.

CIC-DUX sarcomas demonstrate frequent MYC amplification and ETS-family transcription factor expression.

Recent molecular advances have identified a novel, clinically aggressive subgroup of undifferentiated round cell sarcomas defined molecularly by oncogenic fusion of the gene, CIC, and either DUX4 or its paralog, DUX4L, herein termed CIC-DUX sarcomas. Morphologically, CIC-DUX sarcomas are round cell sarcomas with high-grade nuclear features, including vesicular chromatin and nucleoli, patchy clear cell foci, myxoid change, and necrosis. Here, we studied a cohort of 10 cases, including 6 newly identified cases, 2 with paired metastases. Given our prior observation of trisomy 8 in these tumors, we assayed for amplification and expression of MYC (c-Myc) and representative downstream targets. Trisomy 8 was detected in 5/7 testable cases, with further amplification of MYC locus in 6/7 testable cases and immunohistochemical expression of MYC in 10/10. The canonical MYC transcriptional target, p21, but not MTDH, was differentially expressed compared with Ewing sarcomas. Given prior observation of induction of ETS-family transcription factors by the fusion oncoprotein, we assayed and identified highly prevalent positivity for ERG (9/10) and FLI1 (8/8). These findings are cautionary regarding use of these immunostains in prospective case workup, whereas the prevalent MYC amplification may represent a therapeutically targetable oncogenic pathway in CIC-DUX sarcomas.

Ossifying fibromyxoid tumor: a clinicopathologic analysis of 26 subcutaneous tumors with emphasis on differential diagnosis and prognostic factors.

INTRODUCTION: Ossifying fibromyxoid tumor (OFMT) is rare and may present diagnostic difficulty. We describe 26 subcutaneous examples of OFMT emphasizing differential diagnosis and prognostic features. METHODS: Histopathology and follow-up data from archival/consultation cases were reviewed. Prognostic features were assessed according to proposed criteria. RESULTS: Patients (16 female, 10 male) ranged from 26 to 88 years (median 54). The tumors (median 2.3 cm, range 0.8-8.5) involved lower limb (11), trunk (7), head/neck (4), or arm (4). All showed combinations of corded, nested and trabecular patterns in a fibromyxoid stroma. Out of 26 cases 13 had peripheral ossification. Sixteen of 22 cases showed S100 protein expression. Nuclear grade was low (14); intermediate (8) and high (4) while cellularity was low (14); moderate (7) and high (5), with overall good interobserver agreement. Median mitotic rate was 3/50HPF (0-61). Five met criteria for malignant OFMT showing high nuclear grade or high cellularity and mitotic rate >2/50HPF or both. Thirteen OFMTs were atypical. Follow-up (16/26, median 45.5 months, range 8-108) showed that patients with typical OFMT (3) and atypical OFMT (9) remained disease-free. Three malignant examples of OFMT recurred and one metastasized to the lung. No deaths were recorded. CONCLUSIONS: Our results validate proposed prognostic classification of OFMT. Dermatopathologists should be aware of this unusual superficial tumor given its potentially aggressive behavior.

Primary subcutaneous myxoid liposarcoma: a clinicopathologic review of three cases with molecular confirmation and discussion of the differential diagnosis.

BACKGROUND: Myxoid liposarcoma typically presents as a deep-seated mass in the lower extremity of adults. Presentation as a primary subcutaneous tumor is rare. Here we discuss clinicopathologic characteristics of three such cases and their differential diagnosis to alert dermatopathologists to this unusual clinical presentation of a potentially aggressive entity. METHODS: Cases of myxoid liposarcoma were retrieved from archives and consultation files. Inclusion required location above the subcutaneous fascia with no evidence of a metastatic origin. Clinicopathologic features were retrospectively reviewed. Fluorescence in situ hybridization for DDIT3 (CHOP) gene rearrangement was performed on all cases. RESULTS: The tumors affected young adults (two males and one female, mean 36 years, range 32-40 years). No prior history of myxoid liposarcoma or deep soft tissue mass was identified. The tumors occurred in the foot, thigh and hand. All demonstrated multilobular architecture with abundant myxoid stroma, prominent branching capillary vascular network and lipoblastic differentiation. No dermal involvement was seen. Round cell features were identified in one case and represented <5% of the tumor. All patients remain disease-free following local excision only at 6, 8 and 13 months. CONCLUSIONS: Myxoid liposarcoma can rarely present as a primary subcutaneous mass and should be considered in the differential diagnosis of cutaneous myxoid tumors in adults.

Fully automated dual-color dual-hapten silver in situ hybridization staining for MYC amplification: a diagnostic tool for discriminating secondary angiosarcoma.

BACKGROUND: MYC amplification occurs in post-radiation and chronic lymphedema-associated secondary angiosarcoma and some primary angiosarcomas. In this study, we tested the ability of automated dual-color dual-hapten in situ hybridization (DISH) staining to discriminate secondary angiosarcoma from radiation-associated atypical vascular lesions (AVL), and to correlate with fluorescence in situ hybridization (FISH) for MYC amplification. METHODS: Cases of secondary angiosarcoma, including 11 biopsies and 3 excisions from 11 patients, and 5 AVL biopsies from 5 patients, were examined by FISH and DISH. DISH staining was performed using the Dual Color Open Probe software on a Ventana Benchmark XT automated slide stainer. Metallic black silver (MYC) and reference CHR8 red signals were qualitatively and semi-quantitatively enumerated for tumor nuclei. Small and large clusters of silver signals were recorded as 6 or 12 signals, respectively. MYC amplification was defined as MYC/CHR8 ratio >2.0. RESULTS: Where tissue was available for both DISH and FISH, all secondary angiosarcoma cases showed MYC amplification (11/11 = 100%) by both DISH and FISH. All AVL were negative for MYC amplification by both techniques (0/5 = 0%). CONCLUSION: In the current cohort, use of DISH identified all MYC amplified cases, and distinguished secondary angiosarcoma from AVL. DISH staining may be useful in distinguishing secondary angiosarcoma from AVL in challenging cases.

Successful Treatment of Metastatic Primary Cutaneous Adnexal Carcinoma With a PD-1 Inhibitor.

SUMMARY: Standard of care treatment for metastatic cutaneous adnexal carcinomas is not well established. In this case report, we highlight the successful use of anti-programmed cell death protein 1 (anti-PD-1) therapy in treating a patient with low tumor mutation burden, microsatellite stable, high programmed death-ligand 1 (PD-L1) gene expression, metastatic primary cutaneous adnexal carcinoma with significant radiographic, and circulating tumor DNA response with durable benefit. Immune checkpoint inhibitors hold promise as a future treatment option in rare instances of metastatic disease from primary skin adnexal carcinoma. Further studies are needed to identify better immune checkpoint inhibitor predictive biomarkers for rare, advanced-stage non-melanoma skin cancers.

Combining Dual Checkpoint Immunotherapy with Ablative Radiation to All Sites of Oligometastatic Non-Small Cell Lung Cancer: Toxicity and Efficacy Results of a Phase 1b Trial.

PURPOSE: Ablative local treatment of all radiographically detected metastatic sites in patients with oligometastatic non-small cell lung cancer (NSCLC) increases progression-free survival (PFS) and overall survival (OS). Prior studies demonstrated the safety of combining stereotactic body radiation therapy (SBRT) with single-agent immunotherapy. We investigated the safety of combining SBRT to all metastatic tumor sites with dual checkpoint, anticytotoxic T-lymphocyte-associated protein 4 (anti-CTLA-4), and anti-programmed cell death ligand 1 (anti-PD-L1) immunotherapy for patients with oligometastatic NSCLC. METHODS AND MATERIALS: We conducted a phase 1b clinical trial in patients with oligometastatic NSCLC with up to 6 sites of extracranial metastatic disease. All sites of disease were treated with SBRT to a dose of 30 to 50 Gy in 5 fractions. Dual checkpoint immunotherapy was started 7 days after completion of radiation using anti-CTLA-4 (tremelimumab) and anti-PD-L1 (durvalumab) immunotherapy for a total of 4 cycles followed by durvalumab alone until progression or toxicity. RESULTS: Of the 17 patients enrolled in this study, 15 patients received at least 1 dose of combination immunotherapy per protocol. The study was closed early (17 of planned 21 patients) due to slow accrual during the COVID-19 pandemic. Grade 3+ treatment-related adverse events were observed in 6 patients (40%), of which only one was possibly related to the addition of SBRT to immunotherapy. Median PFS was 42 months and median OS has not yet been reached. CONCLUSIONS: Delivering ablative SBRT to all sites of metastatic disease in combination with dual checkpoint immunotherapy did not result in excessive rates of toxicity compared with historical studies of dual checkpoint immunotherapy alone. Although the study was not powered for treatment efficacy results, durable PFS and OS results suggest potential therapeutic benefit compared with immunotherapy or radiation alone in this patient population.

Expression of epithelial-mesenchymal transition regulators SNAI2 and TWIST1 in thyroid carcinomas.

Epithelial-mesenchymal transition is an important mechanism of epithelial tumor progression, local invasion and metastasis. The E-cadherin (CDH1) repressor SLUG (SNAI2) and the basic helix-loop-helix transcription factor TWIST1 inhibit CDH1 expression in poorly differentiated malignancies as inducers of epithelial-mesenchymal transition. Epithelial-mesenchymal transition has been implicated in progression from well to poorly differentiated/anaplastic thyroid carcinoma but the expression of SNAI2 and TWIST1 proteins and their phenotypic association in human thyroid cancers has not been extensively studied. We examined the expression of SNAI2, TWIST1 and CDH1 by immunohistochemistry in a panel of well-differentiated and anaplastic thyroid cancers and by qRT-PCR in thyroid cell lines. Ten normal thyroids, 33 follicular adenomas, 56 papillary thyroid carcinomas including 28 follicular variants, 27 follicular carcinomas and 10 anaplastic thyroid carcinomas were assembled on a tissue microarray and immunostained for SNAI2, TWIST1 and CDH1. Most (8/10) anaplastic thyroid carcinomas demonstrated strong nuclear immunoreactivity for SNAI2 with associated absence of CDH1 in 6/8 cases (75%). TWIST1 was expressed in 5/10 anaplastic thyroid carcinomas with absence of CDH1 in 3/5 (60%) cases. These findings were confirmed in whole sections of all anaplastic thyroid carcinomas and in a separate validation set of 10 additional anaplastic thyroid carcinomas. All normal thyroids, follicular adenomas, papillary and follicular thyroid carcinomas were negative for SNAI2 and TWIST1 (P<0.0001) and all showed strong diffuse immunoreactivity for CDH1 (P=0.026). Expression of SNAI2, TWIST1 and CDH1 mRNA varied in a normal thyroid, papillary carcinoma and two anaplastic thyroid carcinoma cell lines tested, but the highest levels of CDH1 mRNA were detected in the normal thyroid cell line while the anaplastic thyroid carcinoma cell line demonstrated the highest levels of SNAI2 and TWIST1 mRNA. Our findings support the role of epithelial-mesenchymal transition in the development of anaplastic thyroid carcinoma.

Expression of angiopoietin-TIE system components in angiosarcoma.

Angiosarcoma is an aggressive malignancy of endothelial differentiation. Potential roles of the endothelial angiopoietin-tunica interna endothelial cell kinase (ANGPT-TIE) system in angiosarcoma diagnosis, pathogenesis, prognosis and treatment are undefined. To examine the expression and prognostic significance of angiopoietin-1, angiopoietin-2, TIE1 and TEK (TIE2) proteins in angiosarcoma, we immunohistochemically evaluated clinically annotated human angiosarcoma samples. Correlations of protein expression with overall survival and pathological features were explored. The cohort included 51 patients diagnosed with angiosarcoma at the age of 30-86 years (median 67). The 5-year overall survival was 45% with a median of 26 months. Moderate to strong expression of angiopoietin-1, TIE1 and TEK (TIE2) was identified in the majority of angiosarcomas and moderate to strong expression of angiopoietin-2 was observed in 42% of angiosarcomas. Increased angiopoietin-1 expression correlated with improved survival. Non-significant trends toward longer survival were also observed with increased TIE1 and TEK (TIE2) expression. Increased expression of angiopoietin-2, TIE1 and TEK (TIE2) was associated with vasoformative architecture. No differences in expression of these proteins were observed when patients were segregated by age, gender, presence or absence of metastases at diagnosis, primary tumor location, radiation association or the presence of necrosis. We conclude that components of the ANGPT-TIE system are commonly expressed in angiosarcomas. Reduced expression of these proteins is associated with non-vasoformative and clinically more aggressive lesions.

Nondiagnostic fine-needle aspirations of the thyroid: is the risk of malignancy higher?

BACKGROUND: Nondiagnostic fine-needle aspirations (FNAs) pose a dilemma in the management of patients with thyroid nodules. In most cases, these patients undergo either repeat FNA or surgical resection. However, a significant number of patients will only be observed, assuming that the risk of malignancy is low. Therefore, the purpose of this study was to determine whether the risk of malignancy is higher in patients with thyroid nodules and nondiagnostic FNAs. METHODS: We reviewed reports from 4286 consecutive FNA biopsies performed on patients with thyroid nodules at our institution between 2002 and 2010. We divided FNAs into two categories: diagnostic and nondiagnostic. We collected demographic, follow-up, and pathology data from both groups and then analyzed them with analysis of variance and chi-square tests. RESULTS: Of the 4286 FNAs, 259 were classified as nondiagnostic (6%). We saw no significant differences in age or gender between patients with diagnostic versus nondiagnostic FNAs. Of the patients with nondiagnostic FNAs, 62 underwent diagnostic thyroidectomy (24%), 74 had a repeat FNA (29%), and 123 had observation only (47%); thus, 136 patients had a cytologic or pathologic diagnosis. Patients with nondiagnostic FNAs had a significantly higher rate of all types of thyroid cancer, compared with those with diagnostic FNAs (12% versus 5%, respectively; P < 0.001). Impressively, the chance of papillary thyroid cancer was twofold higher in patients with nondiagnostic FNAs. CONCLUSIONS: The percentage of nondiagnostic FNA at our institution during this period (6%) was relatively low. However, the incidence of malignancy in these patients was significantly higher. Therefore, we recommend that patients with thyroid nodules and nondiagnostic FNAs undergo either repeat biopsy or diagnostic thyroidectomy.

Single-cell RNA sequencing of neurofibromas reveals a tumor microenvironment favorable for neural regeneration and immune suppression in a neurofibromatosis type 1 porcine model.

Neurofibromatosis Type 1 (NF1) is one of the most common genetically inherited disorders that affects 1 in 3000 children annually. Clinical manifestations vary widely but nearly always include the development of cutaneous, plexiform and diffuse neurofibromas that are managed over many years. Recent single-cell transcriptomics profiling efforts of neurofibromas have begun to reveal cell signaling processes. However, the cell signaling networks in mature, non-cutaneous neurofibromas remain unexplored. Here, we present insights into the cellular composition and signaling within mature neurofibromas, contrasting with normal adjacent tissue, in a porcine model of NF1 using single-cell RNA sequencing (scRNA-seq) analysis and histopathological characterization. These neurofibromas exhibited classic diffuse-type histologic morphology and expected patterns of S100, SOX10, GFAP, and CD34 immunohistochemistry. The porcine mature neurofibromas closely resemble human neurofibromas histologically and contain all known cellular components of their human counterparts. The scRNA-seq confirmed the presence of all expected cell types within these neurofibromas and identified novel populations of fibroblasts and immune cells, which may contribute to the tumor microenvironment by suppressing inflammation, promoting M2 macrophage polarization, increasing fibrosis, and driving the proliferation of Schwann cells. Notably, we identified tumor-associated IDO1 +/CD274+ (PD-L1) + dendritic cells, which represent the first such observation in any NF1 animal model and suggest the role of the upregulation of immune checkpoints in mature neurofibromas. Finally, we observed that cell types in the tumor microenvironment are poised to promote immune evasion, extracellular matrix reconstruction, and nerve regeneration.