SPOP and CHD1 alterations in prostate cancer: Relationship with PTEN loss, tumor grade, perineural infiltration, and PSA recurrence.

BACKGROUND: In the non-ETS fusion of prostate cancer (PCa) pathway, SPOP mutations emerge as a distinct oncogenic driver subclass. Both SPOP downregulation and mutation can lead to SPOP target stabilization promoting dysregulation of key regulatory pathways. CHD1 gene is commonly deleted in PCa. CHD1 loss significantly co-occurs with SPOP mutations, resulting in a PCa subclass with increased AR transcriptional activity and with a specific epigenetic pattern. METHODS: In this study, SPOP alterations at mutational and protein levels and CHD1 copy number alterations have been analyzed and correlated with ERG and PTEN protein expression and with the clinical pathological features of the patients. RESULTS: SPOP protein loss has been detected in 42.9% of the cases, and it has been strongly associated with PTEN protein loss (p < .001). CHD1 gene loss has been detected in 24.5% and SPOP mutations in 5.9% of the cases. Loss of CHD1 has been strongly associated with SPOP mutations (p = .003) and has shown a trend to be associated with ERG wt cancers (p = .08). The loss of SPOP protein (p = .01) and the combination of PTEN and SPOP protein loss (p = .002) were both statistically more common in grade group 5 cancers, with a prevalence of 60% and 37.5%, respectively. Furthermore, SPOP loss/PTEN loss and SPOP wt/PTEN loss phenotypes were strongly associated with extraprostatic perineural infiltration (p = .007). Strong CHD1 loss was associated with a shorter time to PSA recurrence in the univariate (p = .04), and showed a trend to be associated with the PSA recurrence risk in the multivariate analysis (p = .058). CONCLUSIONS: The results of the present study suggest that the loss of SPOP protein expression, either alone or in combination with loss of PTEN and, on the other hand, a marked loss of the CHD1 gene are very promising prognostic biomarkers in PCa.

Complementary value of electron microscopy and immunohistochemistry in the diagnosis of non-small cell lung cancer: A potential role for electron microscopy in the era of targeted therapy.

With the identification of therapeutic targets for lung adenocarcinoma, it has become mandatory to distinguish it from other entities. Some cases remain classified as non-small cell lung carcinoma, not otherwise specified (NSCLC-NOS) with immunohistochemistry. Electron microscopy (EM) can be useful, allowing the identification of glandular differentiation. The aim of this study was to determine the complementary value of immunohistochemistry and EM.Forty-eight NSCLC-NOS cases were selected (PSMAR-Biobank, Barcelona, Spain). Immunohistochemistry (TTF-1, p40) was performed. Tissue was retrieved from paraffin blocks. Results were compared to the final diagnosis, derived from combination of light microscopy, immunohistochemistry, EM, molecular studies and resection specimen.Immunohistochemistry concurred with final diagnosis in 36 cases (75%, Kappa = 0.517). EM agreed with final diagnosis in 35 (72.9%, Kappa = 0.471). Immunohistochemistry had a sensitivity = 73%, specificity = 100%, positive predictive value (PPV) = 100% and negative predictive value (NPV) = 52.4% for adenocarcinoma. All adenocarcinoma cases not solved by immunohistochemistry (n = 10) were classified by EM, and vice versa. Data from EM were identical to those of immunohistochemistry: sensitivity = 73%, specificity = 100%, PPV = 100% and NPV = 52.4%. Combining both techniques, 47 cases were coincident with final diagnosis (97.9%, Kappa = 0.943).EM can provide valuable information in subtyping NSCLC-NOS, being particularly useful when immunohistochemistry is inconclusive. EM could be considered as a complementary tool for decision-making in NSCLC-NOS.

CD274 (PDL1) and JAK2 genomic amplifications in pulmonary squamous-cell and adenocarcinoma patients.

AIMS: CD274 (PDL1) and JAK2 (9p24.1) gene amplifications have been recently described in pulmonary carcinomas in association with programmed death-ligand 1 (PD-L1) expression. Furthermore, PTEN loss has been explored preclinically in relation to PD-L1 expression. Our aim was to determine whether these genomic alterations affect PD-L1 expression levels in non-small-cell lung cancer. METHODS AND RESULTS: PD-L1 and PTEN expression determined by immunohistochemistry (IHC), and CD274, JAK2 and PTEN copy number alterations (CNAs) determined by fluorescence in-situ hybridisation, were studied in 171 pulmonary carcinoma specimens. PD-L1 expression was positive in 40 cases (23.3%), and CD274 amplification was present in 14 tumours (8.8%). Concordance between both events was found in 12 of 14 amplified cases (P = 0.0001). We found nine JAK2-amplified cases (5.7%), seven with PD-L1 expression (P = 0.0006). Moreover, six of the seven cases had JAK2 and CD274 coamplification (9p24.1 genomic amplification). Remarkably, the average PD-L1 IHC score was higher in these amplified cases (230 versus 80; P = 0.001). Non-statistical associations were observed between PD-L1 expression and PTEN loss and PTEN deletions. CONCLUSIONS: We describe a subset of patients (8.2%) who had 9p24.1 amplifications resulting in high expression of PD-L1. Our results provide evidence for genomic up-regulation of PD-L1 expression in non-small-cell lung cancer.

Concurrent TMPRSS2-ERG and SLC45A3-ERG rearrangements plus PTEN loss are not found in low grade prostate cancer and define an aggressive tumor subset.

BACKGROUND: SLC45A3 is the second most common ERG partner in prostate cancer (PrCa). Coexisting TMPRSS2 and SLC45A3 rearrangements are found in a subset of cases, but the meaning is still unknown. METHODS: SLC45A3-ERG and TMPRSS2-ERG rearrangements and their association with ERG and PTEN expression and with clinical and pathological features have been analyzed in 80 PrCa (PSMAR-Biobank, Barcelona, Spain). ERG and PTEN mRNA were assessed by qRT-PCR; TMPRSS2-ERG and SLC45A3-ERG by RT-PCR, FISH, and direct sequencing; and ERG expression by IHC. The endpoints were Gleason score (GS), stage, and PSA progression-free survival. RESULTS: Single TMPRSS2-ERG was found in 51.6% GS ≤ 7 and 22.2% GS ≥ 8 tumors (P = 0.027). SLC45A3-ERG was found in 25 cases, 20 of them with concurrent TMPRSS2-ERG rearrangement: 11.5% GS = 6, 22.2% GS = 7, and 50% GS ≥ 8 tumors (P = 0.013). Double rearrangements were associated with higher levels of ERG mRNA (P = 0.04). Double rearrangement plus PTEN loss was detected in 0% GS = 6; 14.7% GS = 7, and 29.4% GS ≥ 8 tumors (P = 0.032). Furthermore, this triple change was present in 19.2% stage T3-4 but not in any of stage T2 tumors (P = 0.05). No relationship was found with PSA progression-free survival. CONCLUSIONS: Single TMPRSS2-ERG translocation is associated with low grade PrCa. Subsequent development of SLC45A3-ERG results in higher ERG expression. The combination of double rearrangement plus PTEN loss, according to our series, is never found in low grade, low stage tumors. These findings could be potentially useful in therapeutic decision making in PrCa. Tumors with combined TMPRSS2-ERG/SLC45A3-ERG fusions plus PTEN loss should be excluded from watchful waiting and are candidates for intensive therapy. Prostate 76:854-865, 2016. © 2016 Wiley Periodicals, Inc.

Interstitial 13q14 deletions detected in the karyotype and translocations with concomitant deletion at 13q14 in chronic lymphocytic leukemia: different genetic mechanisms but equivalent poorer clinical outcome.

Deletion of 13q14 as the sole abnormality is a good prognostic marker in chronic lymphocytic leukemia (CLL). Nonetheless, the prognostic value of reciprocal 13q14 translocations [t(13q)] with related 13q losses has not been fully elucidated. We described clinical and biological characteristics of 25 CLL patients with t(13q), and compared with 62 patients carrying interstitial del(13q) by conventional G-banding cytogenetics (CGC) [i-del(13q)] and 295 patients with del(13q) only detected by fluorescence in situ hybridization (FISH) [F-del(13q)]. Besides from the CLL FISH panel (D13S319, CEP12, ATM, TP53), we studied RB1 deletions in all t(13q) cases and a representative group of i-del(13q) and F-del(13q). We analyzed NOTCH1, SF3B1, and MYD88 mutations in t(13q) cases by Sanger sequencing. In all, 25 distinct t(13q) were described. All these cases showed D13S319 deletion while 32% also lost RB1. The median percentage of 13q-deleted nuclei did not differ from i-del(13q) patients (73% vs. 64%), but both were significantly higher than F-del(13q) (52%, P < 0.001). Moreover, t(13q) patients showed an increased incidence of biallelic del(13q) (52% vs. 11.3% and 14.9%, P < 0.001) and higher rates of concomitant 17p deletion (37.5% vs. 8.6% and 7.2%, P < 0.001). RB1 involvement was significantly higher in the i-del(13q) group (79%, P < 0.001). Two t(13q) patients (11.8%) carried NOTCH1 mutations. Time to first treatment in t(13q) and i-del(13q) was shorter than F-del(13q) (67, 44, and 137 months, P = 0.029), and preserved significance in the multivariate analysis. In conclusion, t(13q) and del(13q) patients detected by CGC constitute a subgroup within the 13q-deleted CLL patients associated with a worse clinical outcome.

Complex Karyotype Detection in Chronic Lymphocytic Leukemia: A Comparison of Parallel Cytogenetic Cultures Using TPA and IL2+DSP30 from a Single Center.

Current CLL guidelines recommend a two parallel cultures assessment using TPA and IL2+DSP30 mitogens for complex karyotype (CK) detection. Studies comparing both mitogens for CK identification in the same cohort are lacking. We analyzed the global performance, CK detection, and concordance in the complexity assessment of two cytogenetic cultures from 255 CLL patients. IL2+DSP30 identified more altered karyotypes than TPA (50 vs. 39%, p = 0.031). Moreover, in 71% of those abnormal by both, IL2+DSP30 identified more abnormalities and/or abnormal metaphases. CK detection was similar for TPA and IL2+DSP30 (10% vs. 11%). However, 11/33 CKs (33%) were discordant, mainly due to the detection of a normal karyotype or no metaphases in the other culture. Patients requiring treatment within 12 months after sampling (active CLL) displayed significantly more CKs than those showing a stable disease (55% vs. 12%, p < 0.001). Disease status did not impact cultures' concordance (κ index: 0.735 and 0.754 for stable and active). Although CK was associated with shorter time to first treatment (TTFT) using both methods, IL2+DSP30 displayed better accuracy than TPA for predicting TTFT (C-index: 0.605 vs. 0.580, respectively). In summary, the analysis of two parallel cultures is the best option to detect CKs in CLL. Nonetheless, IL2+DSP30 could be prioritized above TPA to optimize cytogenetic assessment in clinical practice.

CD133 expression in circulating tumor cells from breast cancer patients: potential role in resistance to chemotherapy.

CD133 has been associated with cell properties such as self renewal, migration and vasculogenic mimicry, potentially involved in generation of circulating tumor cells (CTCs). We characterized CD133 expression in CTCs of 98 nometastatic breast cancer (BC) patients. CTCs were isolated by immunomagnetic techniques using magnetic beads labeled with a multicytokeratin(CK)-specific antibody (CK3-11D5) and CTCs and CD133 detection through immunocytochemical methods. CK(+) /CD133(+) CTCs were identified in 65% of patients at baseline and 47.8% after systemic therapy (p = 0.53). Correlation of CD133 status in CTCs with classical clinicopathological characteristics and response to therapy was performed. Her2 not amplified and low Ki-67 index were positively correlated with presence of CK(+) /CD133(+) CTCs. Before any treatment, CK(+) /CD133(+) CTCs were more frequently isolated in patients with luminal BC subtype. No statistically significant differences were found between proportion of CK(+) /CD133(+) CTCs and BC subtypes after systemic therapy, implying a relative enrichment of CK(+) /CD133(+) CTCs in triple negative and HER2-amplified tumors. While CK(+) /CTCs decreases after chemotherapy when analyzing the whole population, CK(+) /CD133(+) CTCs were enriched in post-treatment samples in nonluminal BC subtypes. These findings suggest the potential role of CD133 as a promising marker of chemoresistance in nonluminal BC patients. Further prospective studies and extensive preclinical modeling will be needed to confirm whether CD133 is a marker of resistance to chemotherapy, and its role as a target for novel anticancer therapies targeting cancer stem cells and tumor vasculature.

MYC and TP53 Alterations but Not MAPK Pathway Mutations Are Common Oncogenic Mechanisms in Follicular Dendritic Cell Sarcomas.

CONTEXT.­: Despite their stromal origin, follicular dendritic cells (FDCs) share many functions with hematopoietic system cells. FDC neoplasms are currently classified by the World Health Organization along with those of a histiocytic nature. However, the molecular alterations driving oncogenesis in FDC sarcomas (FDCSs) are beginning to be unveiled and do not seem to concur with those described in histiocytic neoplasms, namely MAPK pathway activation. OBJECTIVE.­: To identify molecular alterations driving tumorigenesis in FDCS. DESIGN.­: We investigated the role of MYC and TP53 in FDC-derived tumor oncogenesis and assessed comprehensively the status of the MAPK pathway in 16 FDCSs, 6 inflammatory pseudotumor (IPT)-like FDCSs, and 8 IPTs. RESULTS.­: MYC structural alterations (both amplifications and rearrangements) were identified in 5 of 14 FDCSs (35.7%), all associated with MYC overexpression. TP53 mutations were identified in 4 of 14 FDCSs (28.6%), all of which displayed intense and diffuse p53 expression. None of these alterations were identified in any IPT-like FDCSs or in IPT cases. No MAPK pathway gene alterations were identified in any of the cases studied. CONCLUSIONS.­: The presence of MYC and TP53 alterations and the lack of association with Epstein-Barr virus segregate classical FDCS from IPT-like FDCS, pointing at different oncogenic mechanisms in both entities. Our results suggest a possible oncogenic role of MYC and TP53 alterations in FDCS. The absence of MAPK pathway alterations confirms the lack of a significant role of this pathway in the oncogenesis of FDC-derived neoplasms.

Round-robin testing for LMO2 and MYC as immunohistochemical markers to screen MYC rearrangements in aggressive large B-cell lymphoma.

Aggressive large B-cell lymphomas (aLBCL) include a heterogeneous group of lymphomas with diverse biological features. One of the approaches to the diagnosis of aLBCL is based on the identification of MYC rearrangements (MYC-R), in addition to BCL2 and BCL6 rearrangements by genetic techniques, mainly fluorescent in situ hybridization (FISH). Because of the low incidence of MYC-R, the identification of useful immunohistochemistry markers to select cases for MYC FISH testing may be useful in daily practice. In a previous work, we identified a strong association between the profile CD10 positive/LMO2 negative expression and the presence of MYC-R in aLBCL and obtained good intralaboratory reproducibility. In this study, we wanted to evaluate external reproducibility. To evaluate whether LMO2 can be a reproducible marker between observers 50 aLBCL cases were circulated among 7 hematopathologists of 5 hospitals. Fleiss' kappa index for LMO2 and MYC were 0.87 and 0.70, respectively, indicating high agreement between observers. In addition, during 2021-2022, the enrolled centers included LMO2 in their diagnostic panels to evaluate prospectively the utility of the marker, and 213 cases were analyzed. Comparing LMO2 with MYC, the group of CD10 positive cases showed higher specificity (86% vs 79%), positive predictive value (66% vs 58%), likelihood positive value (5.47 vs 3.78), and accuracy (83% vs 79%), whereas the negative predictive values remained similar (90% vs 91%). These findings place LMO2 as a useful and reproducible marker to screen MYC-R in aLBCL.

Leukemic Involvement Is a Common Feature in Waldenström Macroglobulinemia at Diagnosis.

Waldenström Macroglobulinemia (WM) is a lymphoplasmacytic lymphoma with bone marrow (BM) involvement and IgM monoclonal gammopathy. To date, no studies have focused specifically on peripheral blood (PB) involvement. In this study, 100 patients diagnosed with WM according to the World Health Organization (WHO) criteria were included based on the demonstration of MYD88mut in BM and the availability of PB multiparametric flow cytometry (MFC) analysis. Leukemic involvement by MFC was detected in 50/100 patients. A low percentage of mature small lymphocytes in PB smears was observed in only 15 cases. MYD88mut by AS-qPCR was detected in PB in 65/100 cases. In cases with leukemic expression by MFC, MYD88mut was detected in all cases, and IGH was rearranged in 44/49 cases. In 21/50 patients without PB involvement by MFC, molecular data were consistent with circulating disease (MYD88mut by AS-qPCR 3/50, IGH rearranged 6/50, both 12/50). Therefore, PB involvement by standard techniques was detected in 71/100 patients. MYD88mut was detected in PB by dPCR in 9/29 triple negative cases. Overall, 80% of the patients presented PB involvement by any technique. Our findings support the role of PB MFC in the evaluation of patients with IgM monoclonal gammopathy and provide reliable information on correlation with molecular features. The development of a feasible MFC assay may stand as an objective tool in the classification of mature B cell neoplasms presenting with IgM monoclonal gammopathy.

Comprehensive NGS profiling to enable detection of ALK gene rearrangements and MET amplifications in non-small cell lung cancer.

Introduction: Next-generation sequencing (NGS) is currently widely used for biomarker studies and molecular profiling to identify concurrent alterations that can lead to the better characterization of a tumor's molecular landscape. However, further evaluation of technical aspects related to the detection of gene rearrangements and copy number alterations is warranted. Methods: There were 12 ALK rearrangement-positive tumor specimens from patients with non-small cell lung cancer (NSCLC) previously detected via fluorescence in situ hybridization (FISH), immunohistochemistry (IHC), and an RNA-based NGS assay, and 26 MET high gene copy number (GCN) cases detected by FISH, selected for this retrospective study. All 38 pre-characterized cases were reassessed utilizing the PGDx™ elio™ tissue complete assay, a 505 gene targeted NGS panel, to evaluate concordance with these conventional diagnostic techniques. Results: The detection of ALK rearrangements using the DNA-based NGS assay demonstrated excellent sensitivity with the added benefit of characterizing gene fusion partners and genomic breakpoints. MET copy number alterations were also detected; however, some discordances were observed likely attributed to differences in algorithm, reporting thresholds and gene copy number state. TMB was also assessed by the assay and correlated to the presence of NSCLC driver alterations and was found to be significantly lower in cases with NGS-confirmed canonical driver mutations compared with those without (p=0.0019). Discussion: Overall, this study validates NGS as an accurate approach for detecting structural variants while also highlighting the need for further optimization to enable harmonization across methodologies for amplifications.

Biomarkers characterization of circulating tumour cells in breast cancer patients.

INTRODUCTION: Increasing evidence supports the view that the detection of circulating tumor cells (CTCs) predicts outcomes of nonmetastatic breast cancer patients. CTCs differ genetically from the primary tumor and may contribute to variations in prognosis and response to therapy. As we start to understand more about the biology of CTCs, we can begin to address how best to treat this form of disease. METHODS: Ninety-eight nonmetastatic breast cancer patients were included in this study. CTCs were isolated by immunomagnetic techniques using magnetic beads labelled with a multi-CK-specific antibody (CK3-11D5) and CTC detection through immunocytochemical methods. Estrogen receptor, progesterone receptor and epidermal growth factor receptor (EGFR) were evaluated by immunofluorescence experiments and HER2 and TOP2A by fluorescence in situ hybridization. We aimed to characterize this set of biomarkers in CTCs and correlate it with clinical-pathological characteristics. RESULTS: Baseline detection rate was 46.9% ≥ 1 CTC/30 ml threshold. CTC-positive cells were more frequent in HER2-negative tumors (p = 0.046). In patients younger than 50 years old, HER2-amplified and G1-G2 tumors had a higher possibility of being nondetectable CTCs. Heterogeneous expression of hormonal receptors (HRs) in samples from the same patients was found. Discordances between HR expression, HER2 and TOP2A status in CTCs and their primary tumor were found in the sequential blood samples. Less that 35% of patients switched their CTC status after receiving chemotherapy. EGFR-positive CTCs were associated with Luminal tumors (p = 0.03). CONCLUSIONS: This is the largest exploratory CTC biomarker analysis in nonmetastatic BC patients. Our study suggests that CTC biomarkers profiles might be useful as a surrogate marker for therapeutic selection and monitoring since heterogeneity of the biomarker distribution in CTCs and the lack of correlation with the primary tumor biomarker status were found. Further exploration of the association between EGFR-positive CTCs and Luminal tumors is warranted.

MYC copy number gains are associated with poor outcome in penile squamous cell carcinoma.

PURPOSE: We determined MYC gene numerical aberrations and protein expression at different stages of penile squamous cell carcinoma carcinogenesis. We correlated these findings with clinicopathological parameters and HPV infection. MATERIALS AND METHODS: We evaluated 79 cases of penile squamous cell carcinoma, including 11 in situ and 68 invasive carcinomas. The MYC cytogenetic profile was evaluated by fluorescence in situ hybridization. HPV was detected by polymerase chain reaction amplification. RESULTS: MYC gains were identified in 4 of 11 in situ carcinomas (36%) and 50 of 68 invasive penile squamous cell carcinomas (73%). A significant association between MYC gains, and tumor progression and poor outcome was demonstrated (p <0.05). HPV DNA was detected in 32 of 79 penile squamous cell carcinomas (39%). High risk type 16 was the most prevalent type. MYC numerical aberrations did not correlate with HPV status. A significant association between HPV and MYC protein over expression was noted. In HPV negative cases MYC gains correlated with MYC over expression. CONCLUSIONS: MYC gains progressively increased during penile squamous cell carcinoma progression from in situ samples to metastases. MYC gains were an independent factor for poor prognosis. These findings were independent of HPV infection. MYC expression was increased in samples with HPV infection, probably reflecting direct activation of MYC.

Cytogenetic aberrations and their prognostic value in a series of 330 splenic marginal zone B-cell lymphomas: a multicenter study of the Splenic B-Cell Lymphoma Group.

We conducted a retrospective collaborative study to cytogenetically characterize splenic marginal zone lymphoma (SMZL) and ascertain the prognostic value of chromosomal aberrations. Of 330 cases, 72% displayed an aberrant karyotype, 53% were complex, and 29% had a single aberration. The predominant aberrations were gains of 3/3q and 12q, deletions of 7q and 6q and translocations involving 8q/1q/14q. CD5 expression was detected in 39 of 158 cases (25%). The cytogenetic makeup of the CD5(+) group differed significantly from that of the CD5(-) group. Cases with unmutated IGHV were significantly associated with deletions of 7q and TP53. A strong association was noted between usage of the IGVH1-2 and deletion 7q, 14q alterations, and abnormal karyotype. On univariate analysis, patients with more than or equal to 2 aberrations, 14q alterations, and TP53 deletions had the shortest survival; 7q deletion did not affect survival. On multivariate analysis, cytogenetic aberrations did not retain prognostic significance; the parameters negatively affecting survival were hemoglobin and age. In conclusion, the cytogenetic profile of SMZL is distinct from other B-cell lymphomas. Complexity of the karyotype, 14q aberrations, and TP53 deletions are poor prognostic indicators and may be considered together with other clinicobiologic parameters to ascertain the prognosis of SMZL.

Molecular diagnosis of dermatofibrosarcoma protuberans: a comparison between reverse transcriptase-polymerase chain reaction and fluorescence in situ hybridization methodologies.

Dermatofibrosarcoma protuberans (DFSP) is characterized by the presence of the t(17;22)(q22;q13) that leads to the fusion of the COL1A1 and PDGFB genes. This translocation can be detected by multiplex reverse transcriptase-polymerase chain reaction (RT-PCR) or fluorescence in situ hybridization (FISH) techniques. We have evaluated the usefulness of a dual color dual fusion FISH probe strategy for COL1A1/PDGFB detection in a series of 103 archival DFSPs and compared the obtained results with RT-PCR analyses. FISH and RT-PCR were carried out on paraffin embedded tissue samples. Regarding the RT-PCR approach, all COL1A1 exons and exon 2 of PDGFB were evaluated. Sensitivity, specificity, positive and negative predictive values were assessed considering the histological diagnosis as the gold standard. We also analyzed the relationship between the genetic findings and the clinicopathological variables of the tumors. The COL1A1/PDGFB translocation was detected in 93% of DFSP. Both techniques showed a similar specificity (100%), but FISH was more sensitive than RT-PCR (90% vs. 72%). Regarding, clinicopathological features, a higher percentage of positive cells detected by FISH was significantly associated with the fibrosarcomatous DFSP variant (P < 0.001). Interestingly, all CD34 negative DFSP (n = 5) were positive for COL1A1/PDGFB translocation by both techniques. In conclusion, the majority of DFSP harbor the COL1A1/PDGFB translocation and FISH technique should be recommended as a routine diagnostic tool, especially in cases showing unusual histopathological subtypes and/or immunohistochemical features.

T cell lymphoblastic lymphoma with uncommon CD20 expression.

We report an interesting case of a T lymphoblastic lymphoma (T-LBL) with uncommon CD20 expression. Immunophenotype analysis showed TdT expression with positivity of CD3 and CD7 among other T-lineage markers. Other non-T markers such as CD79a or myeloid-associated antigens were negative. Molecular studies were performed evidencing clonal rearrangements for gamma and beta chain T cell receptor were clonal in the lymph node biopsy. Cytogenetic analysis showed deletions in CDKN2A and NOTCH2 genes. CD20 when present in T-LBL can lead to a false diagnosis of B-LBL. In this scenario, analysis of rearrangements of both immunoglobulin heavy chain B cell receptor and rearrangement of the T cell receptor can be very helpful.

PCM1::JAK2 fusion associates with an atypical form of mycosis fungoides.

Deregulation of JAK-STAT pathway seems to be relevant in mycosis fungoides (MFs). We report the case of a 23-year-old woman diagnosed of atypical MF carrying isolated PCM1::JAK2 fusion and eosinophilia. The disease was refractory to common treatments and progressed increasing the number of large CD30 positive T-cells. After progression, treatment with brentuximab vedotin was decided and decreased the proportion of large cells, but the low-grade component persisted, and the skin lesions worsened. Immunohistochemical expression of p-STAT3 detected in most tumor cells demonstrated the abnormal activation of JAK-STAT pathway. Very few cases of mature T-cell lymphomas carrying PCM1::JAK2 gene fusion have been reported to date, and we review previous cases described with this alteration. Described cases shared similar clinicopathological features and low genetic complexity, and the presence of PCM1::JAK2 fusion associates with a distinctive form of the disease.

Outcomes and molecular profile of oligomonocytic CMML support its consideration as the first stage in the CMML continuum.

Patients with oligomonocytic chronic myelomonocytic leukemia (OM-CMML) are currently classified according to the 2017 World Health Organization myelodysplastic syndromes classification. However, recent data support considering OM-CMML as a specific subtype of chronic myelomonocytic leukemia (CMML), given their similar clinical, genomic, and immunophenotypic profiles. The main purpose of our study was to provide survival outcome data of a well-annotated series of 42 patients with OM-CMML and to compare them to 162 patients with CMML, 120 with dysplastic type (D-CMML), and 42 with proliferative type (P-CMML). OM-CMML had significantly longer overall survival (OS) and acute myeloid leukemia-free survival than did patients with CMML, considered as a whole group, and when compared with D-CMML and P-CMML. Moreover, gene mutations associated with increased proliferation (ie, ASXL1 and RAS-pathway mutations) were identified as independent adverse prognostic factors for OS in our series. We found that at a median follow-up of 53.47 months, 29.3% of our patients with OM-CMML progressed to D-CMML, and at a median follow-up of 46.03 months, 28.6% of our D-CMML group progressed to P-CMML. These data support the existence of an evolutionary continuum of OM-CMML, D-CMML, and P-CMML. In this context, we observed that harboring more than 3 mutated genes, carrying ASXL1 mutations, and a peripheral blood monocyte percentage >20% significantly predicted a shorter time of progression of OM-CMML into overt CMML. These variables were also detected as independent adverse prognostic factors for OS in OM-CMML. These data support the consideration of OM-CMML as the first evolutionary stage within the proliferative continuum of CMML.