Diagnosis of systemic mastocytosis with cryptic deletion of TET2 and DNMT3A resulting from unbalanced translocation.

Systemic mastocytosis (SM) is a rare haematological neoplasm associated with the gain of function mutation KIT D816V in 90% of adult patients. Classically, cytogenetic aberrations are not common except in cases of SM associated with another haematological neoplasm. We highlight here an unusual clinical presentation of SM and demonstrate the utility of advanced cytogenetic analysis (optical genome mapping, OGM) in detecting a novel cytogenetic abnormality resulting in an unusual mechanism of DNMT3A and TET2 loss of function.

Anaplastic lymphoma kinase 5A4 immunohistochemistry as a diagnostic assay in lung cancer: A Canadian reference testing center's results in population-based reflex testing.

BACKGROUND: The presence of anaplastic lymphoma kinase (ALK) rearrangement predicts response to ALK tyrosine kinase inhibitor (TKI) therapy. Fluorescence in situ hybridization (FISH) was the initial reference standard to detect ALK rearrangement, but immunohistochemistry (IHC) using D5F3 has gained acceptance as an alternative diagnostic method. ALK IHC assays using other ALK antibodies have also been used as screening methods, but data supporting their utility as diagnostic tests have not been widely reported. METHODS: Data from reflexive clinical ALK IHC test using the 5A4 clone concurrent with epidermal growth factor receptor (EGFR) mutation testing were analyzed. ALK IHC results were reported as negative (-), equivocal, or positive (+), with equivocal or positive staining validated by FISH break-apart probe testing. Treatment outcomes were reviewed for ALK IHC+ patients. RESULTS: Between 2012 and 2015, 146 (2.5%) cases were reported as ALK IHC+, 188 (3.2%) were reported as equivocal, and 5624 (94.4%) were reported as ALK IHC-. Of the ALK IHC+ cases, 131/143(91.6%) were ALK FISH+. Excluding 6 cases in which FISH was inconclusive or not performed, the positive predictive value was 95.6%, and the negative predictive value was 100%. Most specimens (n = 5352 [89.6%]) were also successfully tested for EGFR. Clinical responses to ALK TKIs were noted in 49 ALK IHC+ patients, with a median progression-free survival of 9.9 months. CONCLUSIONS: ALK 5A4 IHC can serve as a robust diagnostic test for ALK-rearranged lung cancer and is associated with treatment response and survival. Optimized tissue allocation resulted in high success rates of combined reflex EGFR and ALK testing.

A classification system for clinical relevance of somatic variants identified in molecular profiling of cancer.

PURPOSE: Interpretation systems for clinical laboratory reporting of genetic variants for inherited conditions have been widely published. By contrast, there are no existing systems for interpretation and classification of somatic variants found from molecular testing of cancer. METHODS: We designed an assessment protocol and classification system for somatic variants identified through next-generation sequencing molecular profiling of tumor-derived samples and applied these to a pilot dataset of somatic variants found by next-generation sequencing profiling of 158 tumor samples derived from advanced cancer patients examined at the Princess Margaret Cancer Centre. RESULTS: We present a classification system to interpret the significance of genetic variants in molecular analysis of cancer, including the following key factors: (i) known or predicted pathogenicity of the variant; (ii) primary site and tumor histology in which the variant is found; (iii) recurrence of the variant; and (iv) evidence of clinical actionability. We used these factors to develop a five-category somatic variant classification for simplified reporting of variant interpretations to treating oncologists. CONCLUSION: Our somatic variant classification can be of practical value to other clinical molecular laboratories performing cancer genetic profiling by promoting consistent reporting of somatic variants and permitting harmonization of variant data among laboratories and clinical studies.

Treatment outcomes following leukemic transformation in Philadelphia-negative myeloproliferative neoplasms.

Leukemic transformation (LT) is a rare but fatal complication of Philadelphia-negative myeloproliferative neoplasms (MPNs) for which optimal treatment strategies are not known. At our center, we have adopted a treatment approach for LT where patients within the transplant age group who have a reasonable fitness level are treated with curative intent and offered induction chemotherapy. Subsequently, those who respond and have a suitable donor are considered for allogeneic hematopoietic cell transplantation (HCT). In this study, we evaluated the clinical outcomes of this treatment approach in 75 patients with LT. The 2-year overall survival (OS) from the time of LT was 15%. A total of 39 patients (52%) were treated with curative intent (induction ± HCT) and had a 2-y OS of 26% compared with 3% in those noncuratively treated (P < .0001). In the curative intent group, 18 individuals (46%) achieved complete remission (CR) or CR with incomplete recovery and 12 (31%) reverted to a chronic MPN phase, with 17 patients undergoing HCT. Survival of patients posttransplant was significantly improved compared with those who responded to induction but were not transplanted (2-y OS of 47% vs 15%; P = .03). Thus, induction chemotherapy followed by HCT has the potential for long-term disease control in select patients with LT preceded by a MPN.

Referred molecular testing as a barrier to optimal treatment decision making in metastatic non-small cell lung cancer: Experience at a tertiary academic institution in Canada.

BACKGROUND: Molecular testing is critical to guiding treatment approaches in patients with metastatic non-small cell lung cancer (mNSCLC), with testing delays adversely impacting the timeliness of treatment decisions. Here, we aimed to evaluate the time from initial mNSCLC diagnosis to treatment decision (TTD) following implementation of in-house EGFR, ALK, and PD-L1 testing at our institution. METHODS: We conducted a retrospective chart review of 165 patients (send-out testing, n = 92; in-house testing, n = 73) with newly diagnosed mNSCLC treated at our institution. Data were compared during the send-out (March 2017-May 2019) and in-house (July 2019-March 2021) testing periods. We performed a detailed workflow analysis to provide insight on the pre-analytic, analytic, and post-analytic intervals that constituted the total TTD. RESULTS: TTD was significantly shorter with in-house testing (10 days vs. 18 days, p < 0.0001), driven largely by decreased internal handling and specimen transit times (2 days vs. 3 days, p < 0.0001) and laboratory turnaround times (TAT, 3 days vs. 8 days, p < 0.0001), with 96% of in-house cases meeting the international guideline of a ≤ 10-day intra-laboratory TAT (vs. 74% send-out, p < 0.001). Eighty-eight percent of patients with in-house testing had results available at their first oncology consultation (vs. 52% send-out, p < 0.0001), and all patients with in-house testing had results available at the time of treatment decision (vs. 86% send-out, p = 0.57). CONCLUSION: Our results demonstrate the advantages of in-house biomarker testing for mNSCLC at a tertiary oncology center. Incorporation of in-house testing may reduce barriers to offering personalized medicine by improving the time to optimal systemic therapy decision.

Canadian Multicenter Project on Standardization of Programmed Death-Ligand 1 Immunohistochemistry 22C3 Laboratory-Developed Tests for Pembrolizumab Therapy in NSCLC.

INTRODUCTION: The programmed death-ligand 1 (PD-L1) immunohistochemistry (IHC) assay is used to select patients for first or second-line pembrolizumab monotherapy in NSCLC. The PD-L1 IHC 22C3 pharmDx assay requires an Autostainer Link 48 instrument. Laboratories without this stainer have the option to develop a highly accurate 22C3 IHC laboratory-developed test (LDT) on other instruments. The Canadian 22C3 IHC LDT validation project was initiated to harmonize the quality of PD-L1 22C3 IHC LDT protocols across 20 Canadian pathology laboratories. METHODS: Centrally optimized 22C3 LDT protocols were distributed to participating laboratories. The LDT results were assessed against results using reference PD-L1 IHC 22C3 pharmDx. Analytical sensitivity and specificity were assessed using cell lines with varying PD-L1 expression levels (phase 1) and IHC critical assay performance controls (phase 2B). Diagnostic sensitivity and specificity were assessed using whole sections of 50 NSCLC cases (phase 2A) and tissue microarrays with an additional 50 NSCLC cases (phase 2C). RESULTS: In phase 1, 80% of participants reached acceptance criteria for analytical performance in the first attempt with disseminated protocols. However, in phase 2A, only 40% of participants reached the desired diagnostic accuracy for both 1% and 50% tumor proportion score cutoff. In phase 2B, further protocol modifications were conducted, which increased the number of successful laboratories to 75% in phase 2C. CONCLUSIONS: It is possible to harmonize highly accurate 22C3 LDTs for both 1% and 50% tumor proportion score in NSCLC across many laboratories with different platforms. However, despite a centralized approach, diagnostic validation of predictive IHC LDTs can be challenging and not always successful.

Differentially expressed microRNAs in lung adenocarcinoma invert effects of copy number aberrations of prognostic genes.

In many cancers, significantly down- or upregulated genes are found within chromosomal regions with DNA copy number alteration opposite to the expression changes. Generally, this paradox has been overlooked as noise, but can potentially be a consequence of interference of epigenetic regulatory mechanisms, including microRNA-mediated control of mRNA levels. To explore potential associations between microRNAs and paradoxes in non-small-cell lung cancer (NSCLC) we curated and analyzed lung adenocarcinoma (LUAD) data, comprising gene expressions, copy number aberrations (CNAs) and microRNA expressions. We integrated data from 1,062 tumor samples and 241 normal lung samples, including newly-generated array comparative genomic hybridization (aCGH) data from 63 LUAD samples. We identified 85 "paradoxical" genes whose differential expression consistently contrasted with aberrations of their copy numbers. Paradoxical status of 70 out of 85 genes was validated on sample-wise basis using The Cancer Genome Atlas (TCGA) LUAD data. Of these, 41 genes are prognostic and form a clinically relevant signature, which we validated on three independent datasets. By meta-analysis of results from 9 LUAD microRNA expression studies we identified 24 consistently-deregulated microRNAs. Using TCGA-LUAD data we showed that deregulation of 19 of these microRNAs explains differential expression of the paradoxical genes. Our results show that deregulation of paradoxical genes is crucial in LUAD and their expression pattern is maintained epigenetically, defying gene copy number status.

Molecular Profiling of Patients With Advanced Colorectal Cancer: Princess Margaret Cancer Centre Experience.

BACKGROUND: Molecular aberrations in KRAS, NRAS, BRAF, and PIK3CA have been well-described in advanced colorectal cancer. The incidences of other mutations are less known. We report results of molecular profiling of advanced colorectal cancer in an academic cancer center. PATIENTS AND METHODS: Patients with advanced colorectal were enrolled in an institution-wide molecular profiling program. Profiling was performed on formalin-fixed paraffin embedded archival tissues using a customized MassArray panel (23 genes, 279 mutations) or the Illumina MiSeq TruSeq Cancer Panel (48 genes, 212 amplicons, ≥ 500× coverage) in a Clinical Laboratory Improvement Amendments-certified laboratory. PTEN was determined by immunohistochemistry. RESULTS: From March 2012 to April 2014, 245 patients were enrolled. At least one mutation was found in 54% (97/178) and 91% (61/67) of patients using MassArray or MiSeq platforms, respectively (P < .01). Of all patients, KRAS G12/13 mutation was identified in 39%, and non-G12/13 KRAS, BRAF, or NRAS mutations were present in 9%, 6%, and 4%, respectively. Other common mutations included TP53 (68.7%), APC (41.8%), and PIK3CA (13.5%). Co-mutation with KRAS, NRAS, or BRAF was found in 75% of patients with PIK3CA mutation. Of 106 patients with known PTEN immunohistochemistry status, 16% were negative. A higher average number of mutations were observed in right versus left colorectal cancer (P < .01), with 13 of 14 BRAF mutations located in right colon cancer. CONCLUSION: Mutations are common in advanced colorectal cancer. Right colon cancers harbor more genetic aberrations than left colon or rectal cancers. These aberrations may contribute to differential outcomes to anti-epidermal growth factor receptor therapy among patients with right colon, left colon, or rectal cancers.

Prognostic Effect of Complex Karyotype, Monosomal Karyotype, and Chromosome 17 Abnormalities in B-Cell Acute Lymphoblastic Leukemia.

BACKGROUND: The effect of monosomal karyotype (MK), complex karyotype (CK), and chromosome 17 abnormalities (abnl 17) on prognosis in B-cell acute lymphoid leukemia (B-ALL) has not yet been established. PATIENTS AND METHODS: We conducted a retrospective analysis of prognostic factors on 237 adult patients with B-ALL treated at our institution. RESULTS: Older age (older than 60 years), higher white blood cell count (> 30), and abnl 17 were associated with shorter overall survival in univariate analysis, but multivariable analysis only identified older age as an independent poor prognostic actor. There was a significant correlation between abnl 17 and older age. CONCLUSION: In contrast to the patients with acute myeloid leukemia, our results show that MK and CK do not play a predictive role in patients with B-ALL, but further study is required to determine whether specific changes on chromosome 17 might have prognostic value when investigated separately.

ALK+ lung adenocarcinoma in never smokers and long-term ex-smokers: prevalence and detection by immunohistochemistry and fluorescence in situ hybridization.

ALK gene rearrangements are identified in 2-5 % of all non-small cell lung cancer and are more common in lifetime non-smokers with adenocarcinoma, but the prevalence of ALK rearrangements is not as well characterized in long-term ex-smokers (quit >10 years prior to diagnosis). Accurate and timely diagnosis of ALK-rearranged tumors is of clinical importance given the remarkable response to targeted inhibitors. ALK gene rearrangement may be detected by fluorescence in situ hybridization (FISH), and abnormal expression of ALK protein may be detected by immunohistochemistry (IHC), the latter of which is faster and less expensive. The aim of this study is to evaluate the prevalence of ALK rearrangement in non-smokers and long-term ex-smokers with lung adenocarcinoma and to assess the performance of IHC for the detection of ALK+ tumors when compared to FISH. Two hundred fifty-one cases of resected lung adenocarcinoma were retrospectively reviewed, including non-smokers (n = 79) or long-term ex-smokers (n = 172). ALK IHC and ALK FISH were performed on each case. Four cases demonstrated ALK rearrangement by FISH (4/251; 1.6 %). All cases were non-smokers (4/79; 5.1 %), and all were positive for ALK by IHC. No additional cases were considered positive by IHC, and only 26 (10.4 %) cases were considered equivocal using a conservative approach to interpretation, resulting in a sensitivity of 100 % and specificity of 89.5 %. ALK rearrangement was not observed in lung adenocarcinoma arising in long-term ex-smokers, whereas it is seen in up to 5.1 % of lifetime non-smokers. ALK IHC using the 5A4 antibody demonstrates high sensitivity, supporting its use as a screening test.

Multiplex sequencing for EZH2, CD79B, and MYD88 mutations using archival cytospin preparations from B-cell non-Hodgkin lymphoma aspirates previously tested for MYC rearrangement and IGH/BCL2 translocation.

BACKGROUND: Gene rearrangements and specific translocations define some B-cell non-Hodgkin lymphoma (NHL) subtypes. Genome-wide mutational studies have revealed recurrent point mutations with prognostic implications. The goals of this study were to evaluate the feasibility of applying a multiplex mutation assay to archival cytospin preparations (CPs) and to investigate the rate of EZH2, CD79B, and MYD88 mutations in B-cell NHL samples previously tested for MYC rearrangement and/or IGH/BCL-2 translocation. METHODS: DNA was extracted from archival CPs of B-cell NHL cases with previous fluorescence in situ hybridization (FISH) assays for MYC rearrangement and/or IGH/BCL-2 translocation. Multiplex sequencing was performed for the detection of EZH2 (Y641), CD79B (Y196), and MYD88 (L265) mutations. Sanger sequencing was applied to samples with positive results and failed assays. RESULTS: Eighty-eight archival CPs were available from 40 patients. Alterations detected by FISH were: MYC rearrangement (10 cases), IGH/BCL-2 translocations (21 cases), dual translocations (6 cases), and other abnormalities for IGH/BCL-2 (23 cases) and for MYC (16 cases). DNA concentration ranged from 1.88 to 62.85 ng/µL (mean, 9.46 ng/µL). Successful results were obtained in 88.0% of the specimens submitted to multiplex sequencing. With Sanger sequencing, 2 additional mutated cases were found, and all cases with mutations were confirmed. Eight specimens showed mutations: 6 for EZH2, 1 for CD79B, and 1 for MYD88. Among them, 5 cases showed concurrent MYC and/or IGH/BCL-2 translocations and 2 revealed abnormal signals of IGH/BCL-2 and MYC. CONCLUSIONS: CPs archived for up to 6 years are a reliable source of high-quality genomic material for multiplex sequencing. Almost all B-cell NHL with point mutations showed concurrent chromosomal abnormalities.

Canadian anaplastic lymphoma kinase study: a model for multicenter standardization and optimization of ALK testing in lung cancer.

INTRODUCTION: Fluorescence in situ hybridization (FISH) is currently the standard for diagnosing anaplastic lymphoma kinase (ALK)-rearranged (ALK+) lung cancers for ALK inhibitor therapies. ALK immunohistochemistry (IHC) may serve as a screening and alternative diagnostic method. The Canadian ALK (CALK) study was initiated to implement a multicenter optimization and standardization of laboratory developed ALK IHC and FISH tests across 14 hospitals. METHODS: Twenty-eight lung adenocarcinomas with known ALK status were used as blinded study samples. Thirteen laboratories performed IHC using locally developed staining protocols for 5A4, ALK1, or D5F3 antibodies; results were assessed by H-score. Twelve centers conducted FISH using protocols based on Vysis' ALK break-apart FISH kit. Initial IHC results were used to optimize local IHC protocols, followed by a repeat IHC study to assess the results of standardization. Three laboratories conducted a prospective parallel IHC and FISH analysis on 411 consecutive clinical samples using post-validation optimized assays. RESULTS: Among study samples, FISH demonstrated 22 consensus ALK+ and six ALK wild type tumors. Preoptimization IHC scores from 12 centers with 5A4 and the percent abnormal cells by FISH from 12 centers showed intraclass correlation coefficients of 0.83 and 0.68, respectively. IHC optimization improved the intraclass correlation coefficients to 0.94. Factors affecting FISH scoring and outliers were identified. Post-optimization concurrent IHC/FISH testing in 373 informative cases revealed 100% sensitivity and specificity for IHC versus FISH. CONCLUSIONS: Multicenter standardization study may accelerate the implementation of ALK testing protocols across a country/region. Our data support the use of an appropriately validated IHC assay to screen for ALK+ lung cancers.

Applications of array-CGH for lung cancer.

This chapter summarizes the current knowledge on gene copy number changes found in lung tumors, and their application in the diagnosis, prognostication, and prediction of response to chemotherapy. Examples of the identification of specific "driver" oncogenes within amplified DNA segments are described. A model of how array-CGH could be integrated clinically into the routine workup of lung cancers in clinical laboratory is proposed.

CD13 expression is an independent adverse prognostic factor in adults with Philadelphia chromosome negative B cell acute lymphoblastic leukemia.

In adults with precursor-B lymphoblastic leukemia (BCP-ALL) there remain a majority of patients who fall in an intermediate cytogenetics risk category with a heterogenous outcome. We analyzed immunophenotypic and cytogenetic factors retrospectively in 126 consecutive adults with BCR-ABL negative BCP-ALL who were treated with a pediatric-based protocol at a single institution over a 10 year period. In addition to age, WBC and cytogenetic findings, CD13 positivity was an independent poor prognostic indicator for overall survival (OS, p=0.049), event-free survival (EFS, p=0.013), and relapse-free survival (RFS, p<0.001). The prognostic value of CD13 was primarily seen in patients with normal or intermediate risk cytogenetics. A risk model that includes age>60 years, WBC>30×10(9)/L, SWOG high/very high risk cytogenetics and CD13 positivity, performs better than a risk model of cytogenetics alone for stratifying patients by OS (p=0.001), EFS (p=7×10(-4)) and RFS (p=8×10(-4)). Incorporating CD13 into a scoring system provides high discrimination for relapse risk and survival.

CD11b expression correlates with monosomal karyotype and predicts an extremely poor prognosis in cytogenetically unfavorable acute myeloid leukemia.

Several cytogenetic features, including monosomal karyotype (MK), have been associated with unfavorable prognosis in acute myeloid leukemia (AML). However, little is known about the prognostic significance of immunophenotypes in AML patients with unfavorable-risk cytogenetics. We evaluated immunophenotypes, cytogenetics, clinical features and survival outcomes in 233 uniformly treated AML patients who harbored unfavorable cytogenetics. CD11b expression was observed in 145 (70%) of 208 patients and emerged as an independent prognostic factor for inferior overall survival in multivariate analysis (p=0.024). MK and age ≥ 60 years were predictors for lower complete remission rate (p=0.017, p<0.0001, respectively) and shorter overall survival (p=0.024, p<0.0001), while complex karyotype (CK) predicted a shorter overall survival (p=0.013). CD11b expression was strongly correlated with MK and identified a subset of patients with MK who had extremely poor overall survival. We proposed a prognostic scoring model using CD11b positivity, age ≥ 60 years, the presence of MK and the presence of CK to classify the patients into distinct risk groups. We identified the poor prognosis of CD11b expression and validated the adverse influence of MK, CK and age ≥ 60 years in cytogenetically unfavorable AML patients. Our proposed scoring model may be adapted in clinical practice to further the stratification of this high-risk population.

Prognostic value of fibroblast growth factor receptor 1 gene locus amplification in resected lung squamous cell carcinoma.

INTRODUCTION: Fibroblast growth factor receptor 1 (FGFR1) gene amplification was recently reported as a recurrent abnormality in 10% to 20% of primary lung squamous cell carcinomas (SqCCs), and has attracted significant interest as a potential therapeutic target. Limited data are available for its prognostic impact in early-stage SqCC. METHODS: Tissue microarrays containing 135 primary lung SqCCs and 58 matching lymph node metastases were tested by interphase fluorescence in situ hybridization for DNA copy number (CN) abnormalities at the 8p12 region including FGFR1. RESULTS: FGFR1amplification was found in 18.2% (22 of 121 evaluable) of primary SqCC, using a definition of average copies of FGFR1 per cell of 5.0 or more. Concordance rate between primaries and matching lymph node metastases was 97.7% (43 of 44; 7 amplified and 37 nonamplified), with the only discordant case showing CN at approximately the dichotomous cutoff. Similarly, concordance between two separate lymph node metastases in each of 10 patients was 100% (1 amplified and 9 nonamplified). Using various CN cutoffs, we found no statistically significant association between FGFR1 CN abnormalities and patient age, sex, tumor grade, stage, smoking status, disease-free survival, cause-specific survival, or overall survival. CONCLUSION: FGFR1 amplification is not prognostic in resected lung squamous cell carcinoma patients.

Immunohistochemistry is a reliable screening tool for identification of ALK rearrangement in non-small-cell lung carcinoma and is antibody dependent.

INTRODUCTION: Fluorescence in situ hybridization (FISH) is the standard procedure for the detection of anaplastic lymphoma receptor tyrosine kinase (ALK) rearrangement in non-small-cell lung carcinoma (NSCLC) but is expensive and time consuming. We tested three antibodies to ALK, using various detection systems, and hypothesized that ALK immunohistochemistry (IHC) may represent a cost-effective and efficient means of screening for ALK rearrangement in NSCLC. METHODS: We screened 377 stage I or II NSCLC cases in a tissue microarray by FISH and IHC (5A4 [Leica Biosystems Newcastle Ltd, Newcastle upon Tyne, UYnited Kingdom] by Nichirei's N-Histofine ALK detection kit [Nichirei Biosciences inc., Tokyo, Japan], 5A4 by Novocastra with ADVANCE [Dako Canada inc., Burlington, Ontario, Canada], D5F3 by Cell Signaling Technology with ADVANCE [Cell Signalling Technologies inc., Danvers, MA], and DAKO clone ALK1 with FLEX [Dako Canada inc., Burlington, Ontario, Canada] and ADVANCE). IHC was scored as 0, 1+, 2+, or 3+. Possibly positive or positive cases were further analyzed by IHC and FISH on whole section. RESULTS: Tissue microarray results were available on 377 cases by IHC and 273 cases by FISH. Eleven cases were positive or possibly positive by either IHC or FISH, and three cases were positive or possibly positive by both methods. Three cases were ALK-positive by FISH on whole section validation. There was no correlation between semiquantitative IHC score (1+, 2+, 3+) and ALK rearrangement by FISH. D5F3 (Cell Signaling by ADVANCE) and 5A4 (Novocastra by ADVANCE) showed the greatest combination of sensitivity (100%) and specificity (87.5% for 5A4 by Novocastra and 75% for D5F3 by Cell Signaling), and produced no false-negative results. CONCLUSIONS: IHC is a reliable screening tool for identification of ALK rearrangement in NSCLC and is antibody dependent. D5F3 (Cell Signaling) and 5A4 (Novocastra) can be used with FISH for identification of IHC-positive cases to reduce screening costs.

Synovial sarcoma of the brachial plexus: case report.

BACKGROUND AND IMPORTANCE: Synovial sarcoma (SS) is a malignant soft-tissue tumor that rarely involves brachial plexus. The authors report a case of brachial plexus SS and review the relevant literature. CLINICAL PRESENTATION: A 53-year-old woman presented with gradually enlarging right subclavicular mass over 5 years associated with sharp aching pain radiating down toward the radial 3 fingers. On examination, she had a corresponding firm mass in the supraclavicular region with a positive Tinel sign. There was no objective neurological deficit. She underwent partial excision of this mass without any further adjuvant radiation or chemotherapy. Pathology was consistent with SS. CONCLUSION: Lack of any recurrence in this case 6 years after incomplete excision with no adjuvant therapy suggests slow clinical course in some of these sarcomas.

Recurrent hyalinizing clear cell carcinoma of the base of tongue with high-grade transformation and EWSR1 gene rearrangement by FISH.

Hyalinizing clear cell carcinoma (HCCC) is a rare, low-grade salivary gland tumor with clear cells and hyalinized stroma. Prognosis of HCCC is excellent with few cases metastasizing to the lymph nodes and lung. We present a case of a 61-year-old male with recurrent HCCC on the base of tongue. Histologic examination revealed sheets of clear and eosinophilic cells with a background of a myxoid-like matrix. In addition, large, bizarre malignant cells, focal necrosis, and atypical mitotic figures were identified. By immunohistochemistry, the clear cells were positive for CK18, EMA and vimentin, focally positive for CK7 and CD10, but negative for p63, HMWK, SMA and calponin. A metastatic renal cell carcinoma was considered a possibility but the tumor was called "poorly-differentiated carcinoma, NOS". The patient underwent primary radiotherapy. A recurrence was identified at 10 months follow-up. A biopsy of the recurrent tumor showed clear cell differentiation and a predominant cribriform pattern with focal cords of eosinophilic cells invading the stroma. In contrast to the original tumor, no mitotic figures, atypia or necrosis were identified. The combination of lower grade and different architectural patterns appeared markedly different than the previous biopsy and the immunohistochemical pattern was also different. The recurrent tumor showed diffuse positivity for p63 and HMWK. It was negative for CD10, vimentin, SMA and calponin. Fluorescence in situ hybridization (FISH) analysis was positive for rearrangement of the EWSR1 gene in both samples, confirming that this represented a recurrence of the same tumor. It also confirmed that the initial tumor was a HCCC with high-grade transformation.