EWSR1 translocation in primary hyalinising clear cell carcinoma of the thymus.

AIMS: In thymic carcinomas, focal clear cell change is a frequent finding. In addition to a prominent, diffuse clear cell morphology, some of these carcinomas show an exuberant hyalinised extracellular matrix, and therefore probably represent a separate entity. However, a characteristic genomic alteration remains elusive. We hypothesised that, analogous to hyalinising clear cell carcinomas of the salivary gland, hyalinising clear cell carcinomas of the thymus might also harbour EWSR1 translocations. METHODS AND RESULTS: We identified nine archived cases of thymic carcinoma with focal clear cell features and two cases that showed remarkable hyalinised stroma and prominent, diffuse clear cell morphology. These two cases expressed p40 and were negative for Pax8, CD5, and CD117. Programmed death-ligand 1 was highly positive in one case (70%), and negative in the other one. EWSR1 translocation was identified in both cases of hyalinising clear cell carcinoma, and was absent in all nine carcinomas that showed clear cell features without substantial hyalinisation. In one of the EWSR1-translocated cases, a fusion between exon 13 and exon 6 of EWSR1 and ATF1, respectively was identified by next-generation sequencing. CONCLUSIONS: These findings suggest that the EWSR1 translocation and possibly the EWSR1-ATF1 fusion might be unifying genomic alterations for thymic clear cell carcinomas with prominent hyalinised stroma, for which we propose the term 'hyalinising clear cell carcinoma of the thymus'. Because the immunophenotype is unspecific, testing for the EWSR1 translocation might be helpful in discriminating this entity from other thymic neoplasms or metastases, in particular those with clear cell change.

Interobserver Variability in the Histopathologic Assessment of Extrathyroidal Extension of Well Differentiated Thyroid Carcinoma Supports the New American Joint Committee on Cancer Eighth Edition Criteria for Tumor Staging.

Background: Extrathyroidal extension (ETE) by papillary and follicular thyroid carcinoma can be associated with increased risk of tumor recurrence and mortality. In the seventh edition of its Cancer Staging Manual, the American Joint Committee on Cancer (AJCC) defined minimal ETE as the involvement of skeletal muscle (i.e., strap muscles) or perithyroidal soft tissue. The eighth edition of the AJCC Cancer Staging Manual has changed the criteria so that only grossly evident (macroscopic) ETE involving strap muscles (not microscopic ETE involving perithyroidal soft tissue) affects tumor staging. Summary: Concordance of identifying microscopic ETE (as well as extranodal extension by carcinoma metastatic to lymph nodes) was previously evaluated among 11 expert endocrine pathologists. The overall agreement rate was slight when rendering a diagnosis of ETE. Concordance was highest when pathologists assessed the spatial relationship of carcinoma to skeletal muscle. This article discusses the significance of these findings. It also reviews relevant anatomic and developmental considerations related to the boundaries of the thyroid. Conclusions: The results of the concordance study provide additional rationale supporting stringent criteria for diagnosing ETE, as proposed by the eighth edition of the AJCC Cancer Staging Manual. It is expected that these rigid morphologic criteria will potentially reduce interobserver variability and enhance consistency in the diagnosis and staging of thyroid carcinoma.

Solid Papillary Breast Carcinomas Resembling the Tall Cell Variant of Papillary Thyroid Neoplasms: A Unique Invasive Tumor With Indolent Behavior.

Thirteen cases of invasive solid papillary breast carcinomas resembling the tall cell variant of papillary thyroid neoplasms (BPTC) are reported here. Some cases had long-term follow-up. BPTC is a special type of primary breast neoplasm showing a triple-negative profile but low aggressive potential. Knowledge on BPTC is still scanty; therefore, the aim of the present paper was to report on the features of an additional 13 cases. All the patients were female individuals, and the mean age at presentation was 62.6 years; nodule sizes ranged from 0.6 to 2.5 cm (average, 1.6 cm). All the cases were characterized on histology by papillary, follicular as well as solid structures. The cells were columnar, eosinophilic mostly with granular cytoplasms, rich in mitochondria, with the features of oncocytes in no fewer than 7 cases. Estrogen and progesterone receptors as well as HER2 were consistently negative. The Ki67 proliferative index was low. Markers consistent with thyroid origin, such as TTF1 and thyroglobulin, were negative. Five cases stained for mammoglobin and GATA 3 were positive. All cases proved to be invasive and 2 cases each experienced metastases to 1 lymph node (axillary and intramammary). One case of the latter had a local recurrence. Nevertheless, all the patients are alive, free of disease 24 to 132 months after surgery, of which 8 are without further treatment The present series confirms that BPTC is a primary breast tumor of low malignant potential.

Distinctive Histogenesis and Immunological Microenvironment Based on Transcriptional Profiles of Follicular Dendritic Cell Sarcomas.

Follicular dendritic cell (FDC) sarcomas are rare mesenchymal tumors with variable clinical, morphologic, and phenotypic characteristics. Transcriptome analysis was performed on multiple FDC sarcomas and compared with other mesenchymal tumors, microdissected Castleman FDCs, and normal fibroblasts. Using unsupervised analysis, FDC sarcomas clustered with microdissected FDCs, distinct from other mesenchymal tumors and fibroblasts. The specific endowment of FDC-related gene expression programs in FDC sarcomas emerged by applying a gene signature of differentially expressed genes (n = 1,289) between microdissected FDCs and fibroblasts. Supervised analysis comparing FDC sarcomas with microdissected FDCs and other mesenchymal tumors identified 370 and 2,927 differentially expressed transcripts, respectively, and on the basis of pathway enrichment analysis ascribed to signal transduction, chromatin organization, and extracellular matrix organization programs. As the transcriptome of FDC sarcomas retained similarity with FDCs, the immune landscape of FDC sarcoma was investigated by applying the CIBERSORT algorithm to FDC sarcomas and non-FDC mesenchymal tumors and demonstrated that FDC sarcomas were enriched in T follicular helper (TFH) and T regulatory (TREG) cell populations, as confirmed in situ by immunohistochemistry. The enrichment in specific T-cell subsets prompted investigating the mRNA expression of the inhibitory immune receptor PD-1 and its ligands PD-L1 and PD-L2, which were found to be significantly upregulated in FDC sarcomas as compared with other mesenchymal tumors, a finding also confirmed in situ Here, it is demonstrated for the first time the transcriptional relationship of FDC sarcomas with nonmalignant FDCs and their distinction from other mesenchymal tumors.Implications: The current study provides evidence of a peculiar immune microenvironment associated with FDC sarcomas that may have clinical utility. Mol Cancer Res; 15(5); 541-52. ©2017 AACR.

Primary Cerebellar Neuroendocrine Tumors: Chimeras or Real Entities? A Case Report with a 6-Year Follow-Up.

We report the case of a 38-year-old patient who was diagnosed with a cerebellar well-differentiated neuroendocrine tumor (WDNET) in 2009. At first glance, we believed that it was a metastasis from an unrecognized WDNET arising outside the cerebellum. However, despite a prolonged follow-up of 6 years, an extracranial WDNET has never been found. During this time, the tumor recurred locally twice, and the patient was treated with surgery and radiotherapy. At the moment, he enjoys good general conditions and his tumor is under control. Due to the histopathological characteristics and clinical behavior of the tumor, we believe that this is the first report to date of a primary cerebellar WDNET.

Inter-Observer Variation in the Pathologic Identification of Extranodal Extension in Nodal Metastasis from Papillary Thyroid Carcinoma.

BACKGROUND: Extranodal extension (ENE) in lymph node metastases has been shown to worsen the prognosis of papillary thyroid cancer (PTC). Despite the clinical significance of ENE, there are no stringent criteria for its microscopic diagnosis, and its identification is subject to inter-observer variability. The objective of this study was to determine the level of agreement among expert pathologists in the identification of ENE in PTC cases. METHODS: Eleven expert pathologists from the United States, Italy, and Canada were asked to review 61 scanned slides of representative permanent sections of PTC specimens from Mount Sinai Beth Israel Medical Center in New York. Each slide was evaluated for the presence of ENE. The pathologists were also asked to report the criteria they use to identify ENE. RESULTS: The overall strength of agreement in identifying ENE was only fair (κ = 0.35), and the proportion of observed agreement was 0.68. The proportions of observed agreement for the identification of perinodal structures (fat, nerve, skeletal, and thick-walled vessel involvement) ranged from 0.61 to 0.997. CONCLUSIONS: Overall agreement for the identification of ENE is poor. The lack of agreement results from both variation in pathologists' identification of features and disagreement on the histologic criteria for ENE. This lack of concordance may help explain some of the discordant information regarding prognosis in clinical studies when this feature is identified.

Inter-Observer Variation in the Pathologic Identification of Minimal Extrathyroidal Extension in Papillary Thyroid Carcinoma.

BACKGROUND: Extrathyroidal extension (ETE) is a significant prognostic factor in papillary thyroid carcinoma (PTC). Minimal extrathyroidal extension (mETE) is characterized by involvement of the sternothyroid muscle or perithyroid soft tissue, and is generally identified by light microscope examination. Patients with mETE, identified pathologically, are automatically upstaged to pT3. However, the prognostic implications of mETE have been a source of controversy in the literature. Moreover, there is also controversy surrounding the identification of mETE on pathological specimens. The objective of this study was to determine the level of agreement among expert pathologists in the identification of mETE in PTC cases. METHODS: Eleven expert pathologists from the United States, Italy, and Canada were asked to perform a review of 69 scanned slides of representative permanent sections of PTC specimens. Each slide was evaluated for the presence of mETE. The pathologists were also asked to list the criteria they use to identify mETE. RESULTS: The overall strength of agreement for identifying mETE was slight (κ = 0.14). Inter-pathologist agreement was best for perithyroidal skeletal muscle involvement (κ = 0.46, moderate agreement) and worst for invasion around thick-walled vascular structures (κ = 0.02, slight agreement). In addition, there was disagreement over the constellation of histologic features that are diagnostic for mETE, which affected overall agreement for diagnosing mETE. CONCLUSIONS: Overall agreement for the identification of mETE is poor. Disagreement is a result of both variation in individual pathologists' interpretations of specimens and disagreement on the histologic criteria for mETE. Thus, the utility of mETE in staging and treatment of PTC is brought into question. The lack of concordance may explain the apparent lack of agreement regarding the prognostic significance of this pathologic feature.

Uniform Labeling of Blocks and Slides in Surgical Pathology: Guideline From the College of American Pathologists Pathology and Laboratory Quality Center and the National Society for Histotechnology.

CONTEXT: The labeling of paraffin blocks and microscopic glass slides in the practice of surgical pathology varies from institution to institution and introduces potential risk of preanalytic error. Currently there are no evidence-based guidelines regarding the uniform labeling of these materials. OBJECTIVE: To develop recommendations that will address the need for adequate patient identification and provide a consistent method of identifying slides originating from a particular block. DESIGN: - The College of American Pathologists Pathology and Laboratory Quality Center and the National Society for Histotechnology convened a panel of pathologists and histotechnologists with expertise in histology laboratory quality practices to develop labeling recommendations. A systematic evidence review was conducted to address 6 main key questions. Recommendations were derived from strength of evidence, open comment feedback, and expert panel consensus. RESULTS: Twelve guideline statements were established to assist pathology laboratories in developing standardized block and slide labeling practices. These guidelines call for the use of 2 patient identifiers, 1 of which includes the accession number and case type, on all paraffin blocks and slides. Recommendations were also developed to address the order and format in which identifying elements should appear. CONCLUSIONS: Uniform labeling of paraffin blocks and slides derived from patient specimens will provide an important enhancement to patient safety by assuring that all preparations derived from a patient's tissue can be uniquely and unambiguously linked to that patient. Adoption of standardized practices additionally will improve patient care by facilitating interpretation of histologic sections when they are referred in consultation to a second institution.

Desmoplastic small round cell tumor 20 years after its discovery.

Desmoplastic small round cell tumor (DSRCT) was proposed as a distinct disease entity by William L Gerald and Juan Rosai in 1991. Over 850 patients have been reported in the medical literature. A specific translocation, t(11;22)(p13;q12), is seen in almost all cases, juxtaposing the EWS gene to the WT1 tumor suppressor gene. DSRCT is composed of nests of small round cells with polyphenotypic differentiation, typically a mixture of epithelial, mesenchymal and neural features, surrounded by a prominent desmoplastic stroma. DSRCT has a predilection for adolescent and young adult males, and primarily involves the abdominal cavity and pelvis. Survival is low despite their initial response to multimodal treatment. Most patients relapse with disseminated disease that is unresponsive to further therapy.

Machine learning from concept to clinic: reliable detection of BRAF V600E DNA mutations in thyroid nodules using high-dimensional RNA expression data.

The promise of personalized medicine will require rigorously validated molecular diagnostics developed on minimally invasive, clinically relevant samples. Measurement of DNA mutations is increasingly common in clinical settings but only higher-prevalence mutations are cost-effective. Patients with rare variants are at best ignored or, at worst, misdiagnosed. Mutations result in downstream impacts on transcription, offering the possibility of broader diagnosis for patients with rare variants causing similar downstream changes. Use of such signatures in clinical settings is rare as these algorithms are difficult to validate for commercial use. Validation on a test set (against a clinical gold standard) is necessary but not sufficient: accuracy must be maintained amidst interfering substances, across reagent lots and across operators. Here we report the development, clinical validation, and diagnostic accuracy of a pre-operative molecular test (Afirma BRAF) to identify BRAF V600E mutations using mRNA expression in thyroid fine needle aspirate biopsies (FNABs). FNABs were obtained prospectively from 716 nodules and more than 3,000 features measured using microarrays. BRAF V600E labels for training (n=181) and independent test (n=535) sets were established using a sensitive quantitative PCR (qPCR) assay. The resulting 128-gene linear support vector machine was compared to qPCR in the independent test set. Clinical sensitivity and specificity for malignancy were evaluated in a subset of test set samples (n=213) with expert-derived histopathology. We observed high positive- (PPA, 90.4%) and negative (NPA, 99.0%) percent agreement with qPCR on the test set. Clinical sensitivity for malignancy was 43.8% (consistent with published prevalence of BRAF V600E in this neoplasm) and specificity was 100%, identical to qPCR on the same samples. Classification was accurate in up to 60% blood. A double-mutant still resulting in the V600E amino acid change was negative by qPCR but correctly positive by Afirma BRAF. Non-diagnostic rates were lower (7.6%) for Afirma BRAF than for qPCR (24.5%), a further advantage of using RNA in small sample biopsies. Afirma BRAF accurately determined the presence or absence of the BRAF V600E DNA mutation in FNABs, a collection method directly relevant to solid tumor assessment, with performance equal to that of an established, highly sensitive DNA-based assay and with a lower non-diagnostic rate. This is the first such test in thyroid cancer to undergo sufficient analytical and clinical validation for real-world use in a personalized medicine context to frame individual patient risk and inform surgical choice.

Multifocal fibrosing thyroiditis: report of 55 cases of a poorly recognized entity.

During the course of our consultation activity, we have recognized a peculiar form of thyroiditis in which multiple foci of fibrosis, most of which were associated with reactive atypia of the surrounding follicles, are present. We have referred to this condition, both in our consultation reports and in the third series of A.F.I.P. Fascicle on Tumors of the Thyroid Gland, as "multifocal fibrosing thyroiditis" or (less frequently) "multifocal sclerosing thyroiditis," which are descriptive terms that highlight the benign/inflammatory nature of the process, its multiplicity, and its unknown pathogenesis. The aim of this study is to better define the morphologic features of this process and correlate it with some clinical data. With this purpose, the consultation files of one of the authors (J.R.) were searched for cases coded as multifocal fibrosing thyroiditis or multifocal sclerosing thyroiditis in a 20-year period ranging from January 1989 to December 2009. A total of 55 cases were identified that displayed the above-listed features. There were 51 (93%) female and 4 (7%) male patients (F/M=12.75), with ages ranging between 15 and 71 years (mean age, 47.03 y; median age, 44.5 y). Microscopically, multiple foci of fibrosis were identified in all cases, their number ranging from 2 to 51 per case (mean number, 16), with a mean diameter of 3 mm (range: 0.36 to 15.1 mm). Although heterogenous in shape and size, the individual foci were rather similar to each other in composition, being characterized by a fibrotic poorly cellular center that merged with a cellular peripheral zone. Some of the follicular structures present at the periphery of the scar and-to a lesser extent-those entrapped inside it underwent complex reactive and regenerative (atypical) changes that simulated malignancy. We discuss the differential diagnosis with other benign and malignant thyroid conditions and speculate about its pathogenesis and possible relationship with papillary thyroid microcarcinoma.

Tall cell variant of papillary thyroid carcinoma in children: report of three cases with long-term follow-up from a single institution.

Papillary thyroid carcinoma (PTC), tall cell (TC) variant, is exceptional in children. In adults it represents about 20% of PTCs, featuring a high-risk neoplasm, with a 4-fold risk of relapse and a 20-fold relapse-related risk of death. Out of 42 cases of pediatric PTCs, we found 3 cases of PTC-TC (7%) with clinical data at onset and follow-up up to June 2014. They were 3 females aged 13, 15, and 15 years. Local extrathyroid extension was present in 2 cases. Neither nodal nor distant metastases were found. Two patients underwent hemithyroidectomy and 1 patient a total thyroidectomy, followed in all cases by life-long suppressive hormonal therapy. On follow-up, the patients were alive and well after 29, 24, and 29 years, respectively. The rarity of PTC-TC in children was confirmed. The behavior was indolent after a median follow-up of about 29 years, following treatment with hemithyroidectomy in 2 cases and controlled by suppressive hormonal therapy. The results of this series, albeit small, suggest that TC morphology in PTC does not carry the same negative prognostic significance in children as it does in adults. A conservative approach should therefore be considered for these 'pediatric type' cases of this tumor type.

ITMIG consensus statement on the use of the WHO histological classification of thymoma and thymic carcinoma: refined definitions, histological criteria, and reporting.

INTRODUCTION: The 2004 version of the World Health Organization classification subdivides thymic epithelial tumors into A, AB, B1, B2, and B3 (and rare other) thymomas and thymic carcinomas (TC). Due to a morphological continuum between some thymoma subtypes and some morphological overlap between thymomas and TC, a variable proportion of cases may pose problems in classification, contributing to the poor interobserver reproducibility in some studies. METHODS: To overcome this problem, hematoxylin-eosin-stained and immunohistochemically processed sections of prototypic, "borderland," and "combined" thymomas and TC (n = 72) were studied by 18 pathologists at an international consensus slide workshop supported by the International Thymic Malignancy Interest Group. RESULTS: Consensus was achieved on refined criteria for decision making at the A/AB borderland, the distinction between B1, B2, and B3 thymomas and the separation of B3 thymomas from TCs. "Atypical type A thymoma" is tentatively proposed as a new type A thymoma variant. New reporting strategies for tumors with more than one histological pattern are proposed. CONCLUSION: These guidelines can set the stage for reproducibility studies and the design of a clinically meaningful grading system for thymic epithelial tumors.

A prospective assessment defining the limitations of thyroid nodule pathologic evaluation.

BACKGROUND: Clinical management of thyroid neoplasms is based on light microscopic diagnosis, but its accuracy and precision are poorly defined. OBJECTIVE: To assess inter- and intraobserver variability of preoperative cytopathologic and postoperative histopathologic thyroid diagnoses. DESIGN: Samples were collected in a prospective, multicenter trial validating a gene expression classifier between June 2009 and December 2010. SETTING: 14 academic and 35 community clinical sites. PATIENTS: 653 patients with 776 surgically resected thyroid nodules of 1 cm or greater. MEASUREMENTS: Intraobserver concordance among 2 or more central histopathologists who independently read histopathology slides was calculated. Interobserver concordance between the diagnoses made by the central histopathologists and those made by local pathologists were calculated. Intra- and interobserver concordance for cytopathology was similarly calculated by comparing diagnoses made by local pathologists with those made by a central panel of 3 cytopathologists. RESULTS: Concordance on the histopathologic distinction between benign and malignant diagnoses was 91% comparing local with central histopathologists and 90% comparing 2 central histopathologists. Using the 6-category Bethesda System, 64.0% of diagnoses made by local and central cytopathologists and 74.7% of intraobserver diagnoses were concordant. Central cytopathologists made fewer indeterminate diagnoses than local pathologists (41.2% vs. 55.0%). LIMITATIONS: Many local pathologists did not use the Bethesda System, so their reports were translated to allow comparison. The study required histopathology, and the study population and specimens did not encompass all newly evaluated patients with a thyroid nodule. CONCLUSION: Substantial inter- and intraobserver variability exists in the cytopathologic and histopathologic evaluation of thyroid nodules, confirming an inherent limitation of visual microscopic diagnosis. PRIMARY FUNDING SOURCE: Veracyte.

Involvement of the testis and related structures by Rosai-Dorfman disease: report of 2 new cases and review of the literature.

This report describes 2 new cases of testicular involvement by Rosai-Dorfman disease, also known as sinus histiocytosis with massive lymphadenopathy, and reviews the clinical and pathologic features of the other cases documented in the literature (4 cases) or included in the sinus histiocytosis with massive lymphadenopathy registry (7 cases). Our patients were 42 and 68 years of age, respectively, reflecting the usual middle-age of all the previously reported cases in this location, except for 1, which occurred in a child. Five cases were bilateral, and other sites, such as lymph nodes, kidney, skin, and adrenal gland, were involved in 8 cases. The histories were noteworthy in 2 of the cases, inasmuch as 1 patient had chronic lymphocytic leukemia, and another had a B-cell lymphoma. On gross examination, the testicular masses did not exhibit specific diagnostic features, whereas microscopic examination revealed the typical population of histiocytes, with abundant eosinophilic cytoplasm often exhibiting so-called emperipolesis. The differential diagnosis includes non-neoplastic conditions such as granulomatous orchitis, hematolymphoid disorders, a variety of metastatic tumors, and germ cell tumors.