Expression Of T-cell Antigens Research Articles

T-cell receptor gamma gene rearrangement analysis of classic Hodgkin lymphoma using a BIOMED-2 assay: a paraffin-embedded tissue analysis of one hundred cases.

In the new WHO classifications of haematolymphoid tumours (WHO-HAEM5), classic Hodgkin lymphoma (cHL) is categorized into B-cell lymphoid proliferations and lymphomas. Although the majority of Hodgkin Reed-Sternberg (HRS) cells are of germinal center B-cell origin with some defects of B-cell transcription factors, they rarely express T-cell antigens or cytotoxic molecules. Clonality analyses on cHL samples using BIOMED-2 have been reported by several groups; however, those studies were only focused on Ig regions, including IgH, Ig-kappa, and Ig-lambda, and TCR-γ clonality analysis of cHL has not yet been explored. Here, we investigated TCR-γ gene rearrangement for one hundred cases using a PCR-based method. Four of one hundred (4%) cases showed TCR-γ clonal peaks. Of these, three were at an advanced stage and one patient died of the disease. To clarify whether HRS cells showed T-cell clonality or not, we performed PCR analysis using DNAs of microdissected HRS cells. Three samples showed identical clonal peaks with bulk specimens. Our results indicate that cHL is a heterogeneous disease of mainly B-cell and rarely T-cell origin with a special phenotype. Further molecular studies are warranted.

Phenotypic and genotypic infidelity in B-lineage neoplasms, including transdifferentiation following targeted therapy: Report from the 2021 SH/EAHP Workshop.

Session 2 of the 2021 Society for Hematopathology and European Association for Haematopathology Workshop collected examples of lineage infidelity and transdifferentiation in B-lineage neoplasms, including after targeted therapy. Twenty cases were submitted. Whole-exome sequencing and genome-wide RNA expression analysis were available on a limited subsample. A diagnosis of B-cell acute lymphoblastic leukemia (B-ALL) was rendered on at least 1 biopsy from 13 patients. There was 1 case of acute myeloid leukemia (AML); the remaining 6 cases were mature B-cell neoplasms. Targeted therapy was administered in 7 cases of B-ALL and 4 cases of mature B-cell neoplasms. Six cases of B-ALL underwent lineage switch to AML or mixed-phenotype acute leukemia at relapse, 5 of which had rearranged KMT2A. Changes in maturational state without lineage switch were observed in 2 cases. Examples of de novo aberrant T-cell antigen expression (n = 2) were seen among the mature B-cell lymphoma cohort, and their presence correlated with alterations in tumor cell gene expression patterns. This cohort of cases enabled us to illustrate, discuss, and review current concepts of lineage switch and aberrant antigen expression in a variety of B-cell neoplasms and draw attention to the role targeted therapies may have in predisposing neoplasms to transdifferentiation as well as other, less expected changes in maturational status.

Single-Cell Transcriptome Analysis Reveals Stem Cell-like Subsets in the Progression of Waldenström's Macroglobulinemia

Waldenström's macroglobulinemia (WM) is an uncommon lymphoproliferative disorder characterized by monoclonal immunoglobulin M protein production and bone marrow infiltration by lymphoplasmacytoid cells. It remains an incurable disease. IgM monoclonal gammopathy of undetermined significance (MGUS) is the premalignant condition and is associated with the risk of developing WM. MYD88L265P is a recurrent mutation found in more than 90% of WM patients, and this genetic event is detectable in at least half of IgM MGUS patients. However, the precise cellular landscape and the mechanisms of progression from IgM MGUS to WM remain unclear. Single-cell RNA sequencing (scRNA-seq) provides us a powerful approach to explore tumor heterogeneity and identify rare malignant cells. Anti-CD38 monoclonal antibodies have been introduced into the therapeutic arsenal for plasma cell diseases. Therefore, we analyzed CD38+ immune microenvironment together with B cells and plasma cells to illustrate the first cellular landscape of IgM MGUS and WM in single cell resolution. We isolated bone marrow CD19+ and CD19-CD38+ cells from WM patients(n=3), IgM MGUS patients(n=3) and healthy donors(n=3) and employed the 10x Genomics platform to perform single-cell transcriptomic sequencing. After quality control, our dataset contained a total of 73024 cells. We used UMAP to visualize the cell superclusters and identified clusters including B cells, plasma cells, CD3+CD20+ (CD19+) cells, T cells and NK cells based on the expression of canonical lineage markers and cluster-specific markers. We found that healthy donors had the highest percentage of B cells (72.7% in healthy donors, 19.0% in IgM MGUS patients, 60.5% in WM patients; p<0.001) and that IgM MGUS and WM patients had more NK and T cells than healthy controls (0.06% and 17.7%, respectively, in healthy donors; 24.1% and 20.5% in IgM MGUS patients; 8.5% and 24.0% in WM patients; p<0.001). We also noticed that CD3+CD20+(CD19+) cells were present in both IgM MGUS and WM patients. First, we investigated the cell clusters correlated with WM pathology including B cells and plasma cells. We compared the B-cell gene expression profiles after removing the early B cells. Compared with those of IgM MGUS patients, mature B cells of WM patients showed upregulation of PIM1, DUSP22, HES1, NEAT1, RGS1, RGS16, and GADD45B. Light chain restriction and higher CNV levels were found in B cells of WM patients. SCENIC analysis showed that FOS, FOSB, EGR1 and JUNB were downregulated in B cells from WM and IgM MGUS patients. REL, a proto-oncogene promoting the survival and proliferation of B lymphocytes, was upregulated in B cells of WM patients, and IRF8 and ELF1 were upregulated in B cells of IgM MGUS patients. Nevertheless, plasma cells of WM patients, IgM MGUS patients and healthy donors were colocalized in one cluster, which might indicate their similar gene expression patterns. Next, we further determined the characteristics of B-cell subpopulation with aberrant T-cell antigen expression. Trajectory analysis revealed that CD3+CD20+(CD19+) cells and pro-B cells were located at the same end of the branched structure and were then directed toward mature B cell and plasma cell fates, respectively (Figure. 1A). This inferred developmental trajectory suggested that CD3+CD20+(CD19+) cells may be tumor stem cell-like subset. Using flow cytometry, we validated that CD3 was expressed in a fraction of CD19+ cells (mean: 3.69%, range: 0.28%-15.10%) of bone marrow samples from 8 WM patients. In addition, targeted gene sequencing was performed on CD3+CD19+ and CD3-CD19+ cells from 6 WM patients. MYD88 were proved to be the most frequently mutated gene in this cell subset. And we inferred that MYD88 mutation might be the early events in tumorigenesis by VAF analysis (Figure. 1B). Additional subclonal hits, such as CXCR4 and MAP2K1 mutations, could be acquired during tumor progression. In conclusion, our study provides comprehensive insights into mechanisms of progression from IgM MGUS to WM. We identified the rare CD19+ cell subpopulation with T-cell antigen expression in WM patients. It will be interesting to explore novel therapeutic strategies targeting rare potential cancer-initiating cells in future. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

A Unusual Case of Classic Hodgkin Lymphoma (cHL) with Aberrant T-Antigens Expression

Abstract Introduction/Objective T-cell-associated antigens (TCA) are rarely expressed by Hodgkin/Reed-Sternberg (HRS) cells of classical Hodgkin lymphoma (cHL) and is associated with uncertain clinical significance. Methods/Case Report We present a very recent case of a 68 year-old female with no significant past medical history presented with a large right groin mass for 1 month. She denied any fever, night sweats, fatigue or weight loss. CT abdomen/pelvis showed inguinal/pelvic lymphadenopathy. Resection showed effaced nodal architecture with a vague nodular appearance and with large, atypical nucleolated cells in a background of small, mature lymphocytes and histiocytes. Eosinophils are conspicuously absent in the background. The large cells were polylobated lymphocyte and histiocyte rich (L &amp; H) like, classic HRS cells as well as multinucleated in appearance. The morphologic features overlapped between Classic Hodgkin Lymphoma, and Nodular Lymphocyte Predominant Hodgkin Lymphoma. Given the immunohistochemical (IHC) features of the neoplastic cells [CD45 negative, PAX5+ (weak), CD30+ (strong), CD15+ (majority) and MUM1 +] the diagnosis was most compatible with CHL. Interestingly, a subset of the Hodgkin cells (10-20%) aberrantly expressed a number of T-cell markers (CD2, CD3, CD4, and CD8). However, the background smaller T-cells did not show cytologic atypia or aberrancies of T-cell antigen markers. The large cells were negative for CD43 and ALK1. TCR gamma gene rearrangement was also negative for clonal T-lymphocytes, thus excluding the possibility of peripheral T-cell lymphoma with Hodgkin-like cells. Based on the morphology and IHC profile, this case proves to be CHL with multiple TCA expression including CD2, CD3, CD4 and CD8. She was planned for chemotherapy. Four months after the initial diagnosis and after completion of 2 cycles of chemotherapy, her PET CT scan showed improvement with right inguinal adenopathy being smaller in size and decreased avidity, indicating a response to treatment. She is due for 2 more cycles. Till todate she is doing well with no further symptoms. Results (if a Case Study enter NA) NA. Conclusion So far reported cases of classic Hodgkin lymphoma (CHL) with aberrant T-cell antigen (TCA) expression were associated with decreased event-free survival and overall survival when compared with TCA-negative CHLs. Our finding contributes to the literature and improves our knowledge of the disease.

Individualized Antigen Expression in Precursor T-Cell Acute Lymphoblastic Leukemia

BACKGROUND: In T-acute lymphoblastic leukemia (T-ALL), multi-parametric flow cytometry can serve to detect minimal residual disease (MRD) by using immature or aberrant antigens expression as well as the altered expression of T-cell antigens. The latter approach has been specifically introduced to overcome the absence of leukemia-associated antigens. However, there is no agreed-upon method for the use of T-cell antigens in T-ALL MRD testing. AIMS AND OBJECTIVES: To compare the expression of classic T-cell antigens on T-lymphoblasts and T-lymphocytes to establish a protocol for their use in MRD analysis. MATERIALS AND METHODS: Flow cytometric data of PB or BM samples from 63 adults with T-ALL were collected. We assessed the frequency and degree of brightness or dimness of each T-cell marker, in addition to studying the uniformity of the events scatter of a total of 287 follow-up BM samples from 50 patients. RESULTS: Significant differences in expression intensity of T-cell markers were found between T-lymphoblasts and T-lymphocytes; they were reasonably stable on blasts in follow up samples. This detailed study has nominated the conjoint use sCD3neg/dim and CD5dim/neg in the identification of residual cells, to be supported by other T-cell markers. CONCLUSION: The suggested gating sequence showed an acceptable level of accuracy in detecting residual leukemia, supporting their use in T-ALL MRD especially when other distinguishing markers might be absent in the diagnosis sample, or susceptible to be lost with induction therapy.

Acute Epstein‐Barr virus associated haemophagocytosis in an Asian female: What is the diagnosis?

Acute <scp>Epstein‐Barr</scp> virus associated haemophagocytosis in an Asian female: What is the diagnosis?

PHF6 Mutations Defines a Subgroup of Mixed Phenotype of Acute Leukemia with Aberrant T-Cell Differentiation

Mixed phenotype acute leukemia (MPAL) is a rare form of acute leukemia, and comprises 2% of all acute leukemia diagnoses. With the exception of a small subset harboring BCR/ABL1 or MLL translocations (around 15% in combination), the genetic aberrations of MPAL are largely unknown. PHF6 gene is located at Xq26-27 and encodes plant homeodomain finger 6, a zinc finger containing protein. Recurrent somatic PHF6 mutations are frequent in T-ALL (up to 30%) and rarely in AML (~3%). Here we report recurrent PHF6 mutations in approximately 20% of MPAL patients, making PHF6 the most common genetic aberrations identified in MPAL.From 2013 to 2016, a total of 1329 patients with myeloid neoplasms were sequenced at the MSKCC with a targeted next generation sequencing panel containing 30 genes that are frequently mutated in acute leukemia. We identified 38 PHF6 mutations with predicted pathologic significance in 33 patients (2.5%) spanning the whole coding sequence: 10 frameshift, 11 nonsense, 1 splicing site, and 16 missense (Figure 1). The most common co-mutant gene observed in cases with PHF6 mutations was RUNX1 (30%, 11/37). No TP53 mutations are detected within the PHF6-mutant cohort(Figure 2). The 33 patients with PHF6 mutations included patients with a diagnosis of MPAL (n=5), AML (n=19), MDS (n=5), and MPN (n=4).The disproportional distribution of PHF6 mutations in MPAL prompted us to further analyze these patients. During the same period of time, 24 MPAL patients were identified and confirmed based on WHO 2016 classification (excluding AML-MRC and t-AML). Within this cohort, 3 (12%) had BCR-ABL1 (p190) fusion, and 1 (4%) had MLL translocation, two distinct genetically defined subgroups. Importantly, 5 (21%) harbored PHF6 mutations, these mutations were mutually exclusive with BCR-ABL1 or MLL. Four of the 5 patients showed T-cell lineage differentiation, in contrast to MPAL with BCR-ABL1 or MLL translocations which were characterized by B/myeloid differentiation. The 2-year overall survival for the PHF6 mutation positive MPAL was markedly reduced compared to non-mutated cases (40% vs. 100% in PHF6 unmutated cases (p=0.005)).In the larger subset of AML cases, PHF6 mutations were nearly exclusively present in secondary AML (11 AML-MRC, 6 t-AML and only 1 de novo AML). In contrast to their rarity in de novo AML, PHF6 mutations were identified in 11% (11/88) of AML-MRC and 7.1% (6/84) of t-AML. Interestingly, T-cell markers (cytoplasmic CD3, CD2, CD5, CD7) were often expressed on the blasts of secondary AML cases regardless of PHF6 mutational status (56%, 9/16 vs. unmutated 51%, 36/70). In comparison to unmutated cases, the blasts were often negative for CD33 (69%, 11/16, vs 28%, 20/70, p=0.004 by Fisher's exact test) and CD38 (44%, 7/16, vs. 17%, 12/70, p=0.04 by Fisher's exact test) in PHF6 mutated AML, suggestive of a stemness phenotype with aberrant T-cell differentiation.In conclusion, PHF6 mutations are the most common somatic alteration identified in MPAL and define a subgroup of MPAL with altered T-cell differentiation and inferior outcome. Amongst AML, PHF6 mutations are almost exclusively seen in secondary AML and are also associated with T-cell antigen expression and a more primitive stem/progenitor immunophenotype. PHF6 mutations co-exist with RUNX1 mutations but are mutually exclusive to TP53 mutations. Notably, PHF6 mutations may provide a genetic and functional link between MPALs with poor outcome and secondary AML and provide insights into shared mechanisms of transformation. RNA sequencing studies on the sorted blast population are ongoing and will be presented at the ASH meeting. [Display omitted] DisclosuresArcila:Invivoscribe: Honoraria; Archer: Honoraria; Raindance Tecnologies: Honoraria. Levine:Celgene: Research Funding; Roche: Research Funding; Qiagen: Equity Ownership; Roche: Research Funding; Celgene: Research Funding; Qiagen: Equity Ownership.

A rare case of relapsed multiple myeloma with aberrant T-cell antigen expression and skin plasmacytomas.

A rare case of relapsed multiple myeloma with aberrant T-cell antigen expression and skin plasmacytomas.

Public and private human T-cell clones respond differentially to HCMV antigen when boosted by CD3 copotentiation

AbstractHuman cytomegalovirus (HCMV) induces long-lasting T-cell immune responses that control but do not clear infection. Typical responses involve private T-cell clones, expressing T-cell antigen receptors (TCRs) unique to a person, and public T-cell clones with identical TCRs active in different people. Here, we report the development of a pretherapeutic immunostimulation modality against HCMV for human T cells, CD3 copotentiation, and the clonal analysis of its effects in recall assays at single-cell resolution. CD3 copotentiation of human T cells required identification of an intrinsically inert anti-CD3 Fab fragment that conditionally augmented signaling only when TCR was coengaged with antigen. When applied in recall assays, CD3 copotentiation enhanced the expansion of both public and private T-cell clones responding to autologous HLA-A2(+) antigen-presenting cells and immunodominant NLVPMVATV (NLV) peptide from HCMV pp65 protein. Interestingly, public vs private TCR expression was associated with distinct clonal expansion signatures in response to recall stimulus. This implied that besides possible differences in their generation and selection in an immune response, public and private T cells may respond differently to pharmacoimmunomodulation. Furthermore, a third clonal expansion profile was observed upon CD3 copotentiation of T-cell clones from HLA-A2(−) donors and 1 HLA-A2(+) presumed-uninfected donor, where NLV was of low intrinsic potency. We conclude that human T-cell copotentiation can increase the expansion of different classes of T-cell clones responding to recall antigens of different strengths, and this may be exploitable for therapeutic development against chronic, persistent infections such as HCMV.

CD8 expression in anaplastic large cell lymphoma correlates with noncommon morphologic variants and T-cell antigen expression suggesting biological differences with CD8-negative anaplastic large cell lymphoma

Anaplastic large cell lymphoma (ALCL) is a T-cell neoplasm characterized by uniformly strong CD30 expression and common absence of T-cell markers. Most ALCL cases express CD4, but a small subset of ALCL cases has been reported to express CD8. Little is known about the clinicopathologic and prognostic features of CD8+ ALCL. In this study, CD8 was assessed in 158 patients with systemic ALCL: CD8 was positive in 13 of 67 (19%) ALK+ and 13 of 91 (14%) ALK-negative neoplasms. In ALK+ALCL, the CD8+ subgroup more often showed a noncommon morphologic pattern (69% vs 13%, P=.0001) and was more often positive for CD2 (100% vs 45%, P=.001), CD3 (92% vs 24%, P=.0001), and CD7 (100% vs. 39%, P=.002), but less frequently positive for CD25 (50% vs. 100%, P=.02). Patients with ALK+ALCL and CD8+ neoplasms also had a higher relapse rate (82% vs 48%, P=.05) and more often underwent stem cell transplant (73% vs 36%, P=.04). CD8 expression did not correlate with patient overall survival or progression-free survival regardless of ALK status (all P>0.05). We conclude that CD8+ ALCL cases appear to be biologically different from the more common CD8-negative ALCL cases. Our data suggest that CD8 positivity in ALK+ALCL helps to identify a subset of patients more prone to relapse or more in need of stem cell transplant during their clinical course, although there was no impact on survival in this cohort.

Flow cytometric features of incidental indolent T lymphoblastic proliferations

Indolent T lymphoblastic proliferations have been reported rarely in extramedullary and extrathymic tissues. Recent work has identified these indolent T lymphoblast populations to be mostly CD4+/CD8+ (characterized by immunohistochemistry), with only limited immunophenotypic evaluation of these populations by flow cytometry (FC). We retrospectively reviewed our institutional FC archives and identified 12 samples from 10 patients with incidental T lymphoblastic populations. Samples were characterized with respect to expression of T-cell antigens, CD45, TdT, CD1a, and T/NK antigens, and light scatter properties. Overall, the proportion of T lymphoblasts was small (range 0.01-8.8% of white cells; mean, 1.7%). Histologic correlation showed scattered immature T lymphoblasts in samples without overt distortion of underlying architecture. T lymphoblasts were identified most frequently in association with Castleman disease (four) or tissues with Castleman features (four), marginal zone B-cell lymphoma (one), or tissue with reactive/atypical changes (three cases). Although three cases were composed predominantly of CD4+/CD8+ T cells, the majority of cases in our cohort (eight) included a major subset of CD4-/CD8- T lymphoblasts by FC (one case CD8+/CD4-), which has not been described previously. There was no evidence of subsequent progression to T lymphoblastic leukemia. Incidental, indolent T lymphoblastic proliferations may be detected by clinical FC. In contrast to reports, we find that these proliferations in clinical samples may contain not only CD4+/CD8+ immature T cells but also CD4-/CD8- immature T cells, expanding the immunophenotypic spectrum of this entity.

Revisiting the Tissue Microenvironment of Infectious Mononucleosis: Identification of EBV Infection in T Cells and Deep Characterization of Immune Profiles.

To aid understanding of primary EBV infection, we have performed an in depth analysis of EBV-infected cells and of local immune cells in tonsils from infectious mononucleosis (IM) patients. We show that EBV is present in approximately 50% of B-cells showing heterogeneous patterns of latent viral gene expression probably reflecting different stages of infection. While the vast majority of EBV+ cells are B-cells, around 9% express T-cell antigens, with a predominance of CD8+ over CD4+ cells. PD-L1 was expressed by a median of 14% of EBV+ cells. The numbers of EBER+PD-L1+ cells were directly correlated with the numbers of EBER+CD3+ and EBER+CD8+ cells suggesting a possible role for PD-L1 in EBV infection of T-cells. The microenvironment of IM tonsils was characterized by a predominance of M1-polarized macrophages over M2-polarized cells. However, at the T-cell level, a heterogeneous picture emerged with numerous Th1/cytotoxic cells accompanied and sometimes outnumbered by Th2/regulatory T-cells. Further, we observed a direct correlation between the numbers of Th2-like cells and EBV– B-cells. Also, a prevalence of cytotoxic T-cells over Th2-like cells was associated with an increased viral load. These observations point to contribution of B- and Th2-like cells to the control of primary EBV infection. 35% of CD8+ cells were differentiated CD8+TBET+ cells, frequently detected in post-capillary venules. An inverse correlation was observed between the numbers of CD8+TBET+ cells and viral load suggesting a pivotal role for these cells in the control of primary EBV infection. Our results provide the basis for a better understanding of immune reactions in EBV-associated tumors.

Primary Effusion Lymphoma with Extracavitary Presentation and A T-Cell Immunophenotype: A Potential Diagnostic Pitfall

<p class=MsoListParagraph style=margin:0in;margin-bottom:.0001pt;mso-add-space: auto;text-align:justify;text-indent:0in;line-height:normal;mso-list:l0 level1 lfo1; mso-mirror-indents:yes> 1. Abstract <p class=MsoNormalCxSpMiddle style=margin-bottom:0in;margin-bottom:.0001pt; mso-add-space:auto;text-align:justify;line-height:normal;mso-mirror-indents: yes> Primary Effusion Lymphoma (PEL) is a unique immunodeficiency-associated malignancy that requires infection with Kaposi sarcoma herpesvirus/human herpesvirus 8 (KSHV/HHV8). Although thought to arise from mature B-lymphocytes, PEL typically has a null Immunophenotype but can very rarely show lineage specific aberrancies, including aberrant T-cell markers. Here we present one such case of PEL where aberrant T-cell markers led to a misdiagnosis of peripheral T-cell lymphoma. We performed a review of the literature to identify similar cases of PEL with strong T-cell antigen expression. Most cases occurred in men who were HIV positive or otherwise immunodeficient. Many were EBV positive. Rare cases demonstrated T-cell receptor gene rearrangements. Postulated theories for the cause of disordered differentiation include immunodeficiency and/or EBV infection. The expression of T-cell antigens on PELs may be a source for error in diagnosis and awareness of this correlation is of practical diagnostic relevance. <p class=MsoListParagraph style=margin:0in;margin-bottom:.0001pt;mso-add-space: auto;text-align:justify;text-indent:0in;line-height:normal;mso-list:l0 level1 lfo1; mso-mirror-indents:yes> 2. Keywords: <span style=font-size:10.0pt;font-family: times= new= roman,serif;color:black;mso-themecolor:text1=> Body Cavity Lymphoma; Effusion Lymphoma; Extracavitary Primary Effusion Lymphoma; KSHV/HHV8; PEL; Primary Effusion Lymphoma; T-Cell Primary Effusion Lymphoma

Expression of T-cell receptor signalling pathway components in extranodal NK/T-cell lymphoma.

Although the neoplastic cells of extranodal natural killer (NK)/T-cell lymphoma (ENKTL) usually do not express T-cell antigens, the T-cell receptor (TCR) gene might be rearranged and TCR protein expressed. The aim is to elucidate the expression of the downstream TCR pathway components and their importance in ENKTL. We used formalin-fixed paraffin-embedded tissues from 91 ENKTL samples to immunohistochemically characterise the expression of TCR pathway components. The following proteins were variably expressed: ZAP70 (94%; 83/88), GRAP2/GADS (68%; 60/88), DOK2 (42%; 38/90), LCK (35%; 31/88), and ITK (10%; 9/90). When these tumours were classified as being of T lineage (16%), NK lineage (45%), or indeterminate lineage (38%), the GRAP2/GADS expression rate was higher in T lineage tumours (versus NK, P = 0.0073; versus indeterminate, P = 0.00082). GRAP2/GADS-positive NK lineage tumours more frequently expressed DOK2 (P = 0.0073), and were more often confined to the nasal areas (P = 0.014). Furthermore, when these tumours were immunophenotypically classified into a T signature (42%) or NK signature (58%), the expression rates of GRAP2/GADS and ITK were higher in T signature tumours (P = 0.00074 and P = 0.067, respectively), whereas that of LCK was higher in NK-signature tumours (P = 0.10). Although some ENTKL cases were polyclonal for TCR rearrangement and others lacked TCR expression, we speculate that the TCR pathway might be functioning in ENKTLs. A T signature versus a NK signature might be better for delineating the physiology of ENKTL than cellular lineage. Furthermore, ITK may represent a potential therapeutic target for patients with ITK-expressing tumours.

Immunophenotypic dysplasia and aberrant T-cell antigen expression in acute myeloid leukaemia with complex karyotype and TP53 mutations

AimsCytogenetic and molecular aberrations are the strongest factors in determining outcome in acute myeloid leukaemia (AML). AML with complex karyotype confers a particularly poor prognosis and is associated with morphologic...

Classical Hodgkin Lymphoma With Aberrant CD8 Expression: A Clinicopathologic Study of Five Cases.

Hodgkin/Reed-Sternberg (HRS) cells of classical Hodgkin lymphoma (CHL) are of B-cell origin. In a small number of CHL cases, the tumor cells can express T-cell antigens. CD8 expression in this setting is extremely rare. We identified 5 cases of CHL with aberrant CD8 expression from our database. The patients included 3 men and 2 women with a median age of 33 years (range = 20-59 years). All the patients initially presented with lymphadenopathy and variable number of RS cells. Two cases were classified as mixed cellularity type that showed prominent vascular proliferation mimicking peripheral T-cell lymphoma. Two cases represented nodular sclerosis type. The tumor cells in all cases were positive for CD8 and negative for CD2, CD3, CD4, and CD7 and carried germline T-cell receptor genes. Molecular studies revealed T-cell receptor genes to be in germline configuration in 4 cases with available information. Given the morphologic overlap with peripheral T-cell lymphoma and the rarity of this type of CHL, identifying more cases will help our better understanding of this entity.

Nodal Involvement by CD30+ Cutaneous Lymphoproliferative Disorders and Its Challenging Differentiation From Classical Hodgkin Lymphoma.

Primary cutaneous lymphomas are defined as non-Hodgkin lymphomas that present in the skin with no evidence of extracutaneous disease at the time of diagnosis. Mycosis fungoides is the most common type of primary cutaneous T-cell lymphoma, representing almost 50% of primary cutaneous T-cell lymphomas, and primary cutaneous CD30+ T-cell lymphoproliferative disorders are the second most common group (30%). Transformed mycosis fungoides is usually CD30+ and can involve multiple nodal sites; other primary cutaneous CD30+ T-cell lymphoproliferative disorders can also involve draining regional nodes. Nodal involvement by CD30+ T-cell lymphoproliferative disorders can mimic classical Hodgkin lymphoma, which can aberrantly express T-cell antigens. The aim of this article is to briefly review salient clinical, histologic, immunophenotypic, and molecular features that can be used to distinguish lymph node involvement by CD30+ cutaneous T-cell lymphomas and lymphoproliferative disorders from classical Hodgkin lymphoma, a clinically important differential diagnosis that represents a challenging task for the pathologist.

Immunophenotypic aberrancies in acute lymphoblastic leukemia from 282 Iraqi patients.

The identification of aberrancies in leukemia-associated immunophenotype (LAIP) of acute lymphoblastic leukemia (ALL) is quite important in the assessment of minimal residual disease (MRD). This study, the first from Iraq, aimed to assess the frequency and patterns of LAIP among Iraqi patients with ALL, to establish future strategies for evaluating MRD. A total of 282 newly diagnosed Iraqi ALL cases were analyzed with six-parameter flow cytometry using a panel of 29 monoclonal antibodies. Immunological subtyping revealed that 85.5% of cases were B-ALL and the remainder T-ALL. LAIP was detected in 97.1% of B-ALL, and in 26.8% of T-ALL. The asynchronous maturation-associated antigen patterns in B-ALL were CD10strong+ /TdTdim+ , CD38dim+ /CD34+ , CD10dim+ /CD34+ , CD10strong /CD20strong+ , CD20strong+ /CD34+, and CD45dim+ /CD20strong+ in 84.6%, while the cross-lineage myeloid expression was seen in 81.3% and aberrant T-cell antigen expression in 6.2%. For T-ALL, asynchronous maturation-associated antigen patterns included the following: CD1a+ /CD5+ /sCD3+ and CD34+ /sCD3+ in 12.2%. Myeloid and B-cell antigen expression were each identified in 7.3% of T-ALL. No significant differences in LAIP were found between children and adults. The high rates and the patterns of LAIP particularly in Iraqi B-ALL patients may allow the development of more cost-effective strategies for MRD monitoring.

Systemic and primary cutaneous anaplastic large cell lymphoma: Clinical features, morphological spectrum, and immunohistochemical profile.

Background:T-cell lymphomas with anaplastic morphology typically comprise of anaplastic lymphoma kinase positive, anaplastic large cell lymphoma (ALK+ ALCL), ALK-negative ALCL (ALK- ALCL), and primary cutaneous ALCL (PC-ALCL). However, other entities such as diffuse large B-cell lymphoma, peripheral T-cell lymphoma, Hodgkin lymphoma, and undifferentiated carcinoma can also show similar anaplastic features.Aims:To study the clinical features and histological spectrum of ALCL and emphasize the role of immunohistochemistry (IHC) in their diagnosis and categorization.Setting and Design:Eight cases of ALCL diagnosed over a period of 4 years were selected for the study.Materials and Methods:Histopathological review and IHC was performed on all cases. Two ALK+ ALCL cases were tested by fluorescent in situ hybridization (FISH) for t(2;5)(p23;q35).Results:There were four cases of ALK+ ALCL and two each of ALK- ALCL and PC-ALCL. Histologically, all the subtypes showed pleomorphic and “hallmark” cells with strong CD30 expression and variable loss of T-cell antigens. One case of PC-ALCL was leukocyte common antigen (LCA) negative. Epithelial membrane antigen was positive in all the six systemic ALCL cases. Two cases tested for t(2;5)(p23;q35) by FISH were positive.Conclusions:Diagnosis of ALCL is based on recognizing the key morphological features, especially the presence of “hallmark” cells. IHC is essential for confirmation of diagnosis and excluding other malignancies with anaplastic morphology. The inclusion of CD30 in the initial IHC panel will help identify LCA negative cases and avoid misdiagnosis.

Immunophenotypic Shifts in Primary Cutaneous γδ T-Cell Lymphoma Suggest Antigenic Modulation: A Study of Sequential Biopsy Specimens.

Primary cutaneous γδ T-cell lymphoma (PCGD TCL), an aggressive type of lymphoma, accounts for approximately 1% of all primary cutaneous lymphomas. We have occasionally observed changes in T-cell antigen expression (immunophenotypic [IP] shift) over time, a phenomenon that is considered rare in T-cell lymphoma including cutaneous T-cell lymphoma. Therefore, we assessed sequential biopsies of PCGD TCL for possible IP shifts of the lymphoma cells. We searched for cases of PCGD TCL with consecutive biopsies to perform a comprehensive immunohistochemical analysis of paired specimens. A median of 12 markers per case was tested. We evaluated the percentage of neoplastic lymphocytes and determined the differential expression of antigens (gain, loss, increase or decrease). We identified 9 patients with PCGD TCL with consecutive biopsies. All (100%) cases had IP shifts of at least 1 antigen, whereas overall 22 pairs of markers were shifted: gain of reactivity occurred in 7 (31.8%) and loss in 3 (13.6%); increased reactivity in 4 (18.2%) and decreased in 8 (36.4%). Molecular analysis of TCRγ showed identically sized monoclonal rearrangements between biopsy pairs in 4/4 (100%) patients. There was no correlation between IP shifts and the clinical appearance of lesions, histopathologic or cytologic features, or molecular rearrangements. IP shifts are common in PCGD TCL, occurring in all patients in this study and involving a variety of antigens. IP shifts do not seem to be linked to changes in the T-cell clone and are without obvious clinical or morphologic correlates. The occurrence of IP shifts in PCGD TCL suggests that antigen modulation may be involved in pathogenesis. IP shifts are somewhat frequent in T-cell lymphoma; however, it does not suggest a second neoplasm, and molecular studies can be used to determine clonal identity.