Anaplastic large cell lymphoma: the shifting sands of diagnostic hematopathology

Systemic ALK-negative anaplastic large cell lymphoma with NPM1::TYK2 rearrangement

Anaplastic large cell lymphoma (ALCL) is a rare subtype of non-Hodgkin lymphoma, with most cases harboring ALK gene rearrangement (ALK + ALCL); however, 20-50% of ALCLs do not have the rearrangement (ALK- ALCL) but exhibit distinct genetic alterations. In this report, we present an unusual case of systemic ALK- ALCL with NPM1::TYK2 fusion. Diagnosis of this case was challenging prior to the NGS findings. A comprehensive panel of immunohistochemical and in-situ hybridization studies was conducted. FISH assays were utilized to target the rearrangements of DUSP22 and TP63 genes. Moreover, next-generation sequencing (NGS) assays were performed to detect clonal rearrangements of IGH and TRG genes, somatic mutations, and potential fusions. The lymphoma cells in this case are negative for all hematolymphoid markers stained, except for CD30 expression and focal and weak CD43 expression. However, NGS studies detected clonal TRG rearrangement and NPM1::TYK2 rearrangement, which aid in the diagnosis of ALK- ALCL. NPM1::TYK2 rearrangement is a rare genetic alteration that has been reported in rare cases of primary cutaneous ALCL, mycosis fungoides, and lymphomatoid papulosis. To the best of our knowledge, this is the first reported instance of such rearrangement in systemic ALK- ALCL.

cyTRBC1 evaluation rapidly identifies sCD3-negative peripheral T-cell lymphomas and reveals a novel type of sCD3-negative T-cell clone with uncertain significance

The flow cytometry-based evaluation of TRBC1 expression has been demonstrated as a rapid and specific method for detecting T-cell clones in sCD3-positive TCRαβ+ mature T-cell lymphoma. The aim of the study was to validate the utility of surface (s) TRBC1 and cytoplastic (cy) TRBC1 assessment in detecting clonality of sCD3-negative peripheral T-cell lymphomas (PTCLs), as well as exploring the existence and characteristics of sCD3-negative clonal T-cell populations with uncertain significance (T-CUS). Evaluation of sTRBC1 and cyTRBC1 were assessed on 61 samples from 37 patients with sCD3-negative PTCLs, including 26 angioimmunoblastic T-cell lymphoma (AITL) patients and 11 non-AITL patients. The sCD3-negative T-CUS were screened from 1602 patients without T-cell malignancy and 100 healthy individuals. Additionally, the clonality of cells was further detected through T-cell gene rearrangement analysis. We demonstrated the monotypic expression patterns of cyTRBC1 in all sCD3-negative PTCLs. Utilizing the cyTRBC1 evaluation assay, we identified a novel and rare subtype of sCD3-negative T-CUS for the first time among 13 out of 1602 (0.8%) patients without T-cell malignancy. The clonality of these cells was further confirmed through T-cell gene rearrangement analysis. This subset exhibited characteristics such as sCD3-cyCD3 + CD4 + CD45RO+, closely resembling AITL rather than non-AITL. Further analysis revealed that sCD3-negative T-CUS exhibited a smaller clone size in the lymph node and mass specimens compared to AITL patients. However, the clone size of sCD3-negative T-CUS was significantly lower than that of non-AITL patients in both specimen groups. In conclusion, we validated the diagnostic utility of cyTRBC1 in detecting sCD3-negative T-cell clonality, provided a comprehensive analysis of sCD3-negative T-CUS, and established a framework and provided valuable insights for distinguishing sCD3-negative T-CUS from sCD3-negative PTCLs based on their phenotypic properties and clone size.

Nodal peripheral T-cell lymphoma: Chemotherapy-free management, are we there yet?

Peripheral T-cell lymphomas (PTCLs) are a diverse and uncommon type of lymphoid malignancies with a dismal prognosis. Recent advances in genomic studies have shown recurring mutations that are changing our knowledge of the disease's molecular genetics and pathogenesis. As such, new targeted therapies and treatments to improve disease outcomes are currently being explored. In this review, we discussed the current understanding of the nodal PTCL biology with potential therapeutic implications and gave our insights on the promising novel therapies that are currently under study such as immunotherapy, chimeric antigen receptor T-cell therapy, and oncolytic virotherapy.

Pathological and Molecular Features of Nodal Peripheral T-Cell Lymphomas

Peripheral T-cell lymphomas (PTCLs) are uncommon neoplasms derived from mature T cells or NK cells. PTCLs comprise numerous disease entities, with over 30 distinct entities listed in the latest WHO classification. They predominantly affect adults and elderly people and usually exhibit an aggressive clinical course with poor prognosis. According to their presentation, PTCLs can be divided into nodal, extranodal or cutaneous, and leukemic types. The most frequent primary sites of PTCLs are lymph nodes, with over half of cases showing nodal presentation. Nodal PTCLs include ALK-positive and ALK-negative anaplastic large cell lymphoma; nodal T-cell lymphoma with T follicular helper cell origin; and PTCL, not otherwise specified. Adult T-cell leukemia/lymphoma also frequently affects lymph nodes. Recent pathological and molecular findings in nodal PTCLs have profoundly advanced the identification of tumor signatures and the refinement of the classification. Therefore, the therapies and pathological diagnosis of nodal PTCLs are continually evolving. This paper aims to provide a summary and update of the pathological and molecular features of nodal PTCLs, which will be helpful for diagnostic practice.

Primary Central Nervous System Anaplastic Large Cell Lymphoma, ALK Positive

OBJECTIVES

Primary central nervous system anaplastic large cell lymphoma, anaplastic lymphoma kinase positive (primary CNS ALCL, ALK+) is a rare CNS lymphoma whose description is limited to case reports. These tumors have a variable clinical course, and prognosis is primarily determined by age. We present the largest case series to date of primary CNS ALCL, ALK+, with observational data.

METHODS

A retrospective search of multiple academic centers was performed to identify cases of primary CNS ALCL, ALK+. We also performed a review of published cases of primary CNS ALCL, ALK+. Clinical history, radiography, pathology, and genetic testing data were obtained to determine the prognostic implications in the context of clinical course.

RESULTS

We identified three cases of primary CNS ALCL, ALK+ from our databases. A literature review identified 30 published reports of 31 individual cases. Clinical features for the combined 34 cases included a median age of 18.5 years, with a male to female ratio of 4.7:1, and the most common symptom was headache. Genetic studies demonstrated an ALK rearrangement by fluorescence in situ hybridization, and a gene fusion assay confirmed an NPM1-ALK gene fusion in one case.

CONCLUSIONS

We present the largest case series to date of a rare primary CNS lymphoma with additional diagnostic and clinical information.

Central nervous system ALK-negative anaplastic large cell lymphoma with IRF4/DUSP22 rearrangement

Anaplastic large cell lymphomas (ALCL) are mature T-cell neoplasms, approximately half of which harbor rearrangements of the ALK gene that confer a good prognosis. Recent studies have demonstrated that a significant proportion of ALK-negative ALCLs demonstrate rearrangements of the IRF4/DUSP22 locus that also are typically associated with a favorable prognosis. ALCL with primary involvement of the central nervous system (CNS) is extremely rare. We report what may be the first case of ALK-negative ALCL with IRF4/DUSP22 rearrangement involving the brain in a 55-year-old man. Magnetic resonance imaging demonstrated signal abnormalities in the periventricular region, corpus callosum and cingulate gyrus. Biopsy revealed a diffuse parenchymal and angiocentric infiltrate of CD30-positive cells that showed IRF4/DUSP22 rearrangement by fluorescence in situ hybridization. We also review the clinical and pathologic features of primary CNS ALK-negative ALCLs in the literature and highlight the need for awareness of this entity to optimize appropriate management.

ALK-Negative Anaplastic Large Cell Lymphoma: Current Concepts and Molecular Pathogenesis of a Heterogeneous Group of Large T-Cell Lymphomas

Simple Summary

ALK- anaplastic large cell lymphoma (ALK- ALCL) is a rare subtype of CD30+ large T-cell lymphoma that typically affects older adults and has a poor prognosis. Recognition of its histopathologic spectrum, subtypes, and of other tumors that can resemble ALK- ALCL is crucial to avoid making a wrong diagnosis that could result in inappropriate treatment for a patient. In recent years, several important studies have identified recurrent molecular alterations that have shed light on the pathogenesis of this lymphoma. However, on the other hand, putting all this vast information together into a concise form has become challenging. In this review, we present not only a more detailed view of the histopathologic findings of ALK- ALCL but also, we attempt to provide a more simplified perspective of the relevant genetic and molecular alterations of this type of lymphoma, that in our opinion, is not available to date.

Abstract

Anaplastic large cell lymphoma (ALCL) is a subtype of CD30+ large T-cell lymphoma (TCL) that comprises ~2% of all adult non-Hodgkin lymphomas. Based on the presence/absence of the rearrangement and expression of anaplastic lymphoma kinase (ALK), ALCL is divided into ALK+ and ALK-, and both differ clinically and prognostically. This review focuses on the historical points, clinical features, histopathology, differential diagnosis, and relevant cytogenetic and molecular alterations of ALK- ALCL and its subtypes: systemic, primary cutaneous (pc-ALCL), and breast implant-associated (BIA-ALCL). Recent studies have identified recurrent genetic alterations in this TCL. In systemic ALK- ALCL, rearrangements in DUSP22 and TP63 are detected in 30% and 8% of cases, respectively, while the remaining cases are negative for these rearrangements. A similar distribution of these rearrangements is seen in pc-ALCL, whereas none have been detected in BIA-ALCL. Additionally, systemic ALK- ALCL—apart from DUSP22-rearranged cases—harbors JAK1 and/or STAT3 mutations that result in the activation of the JAK/STAT signaling pathway. The JAK1/3 and STAT3 mutations have also been identified in BIA-ALCL but not in pc-ALCL. Although the pathogenesis of these alterations is not fully understood, most of them have prognostic value and open the door to the use of potential targeted therapies for this subtype of TCL.

Mature T/NK-Cell lymphomas of the oral and maxillofacial region: A multi-institutional collaborative study

BACKGROUND

The diagnosis of oral and maxillofacial mature T/NK-cell neoplasms is challenging because of their rarity, morphological heterogeneity and complex immunophenotype with scarce available data describing their clinical and microscopic aspects. Therefore, in this study, we investigated a series of mature T/NK-cell neoplasms affecting this anatomical region and provided an updated literature review.

METHODS

Cases diagnosed as mature T/NK-cell lymphomas affecting the oral and maxillofacial region were retrospectively retrieved from six pathology files and their diagnoses were confirmed using haematoxylin and eosin-stained slides, immunohistochemical reactions and in situ hybridization for Epstein-Barr virus (EBV) detection. Patients' clinical data were collected from their pathology forms.

RESULTS

A total of 22 cases were included in this study. Eleven (50%) consisted of extranodal NK/T-cell lymphomas, nasal type; eight (36.4%) were peripheral T-cell lymphomas, NOS; two (9.1%) were adult T-cell leukaemia/lymphomas, and one (4.5%) was an ALK-positive anaplastic large cell lymphoma. Overall, males predominated, with a mean age of 55.7 years. The palate was the most affected site (50%), and tumours usually presented as destructive and painful ulcers. EBV was present in all cases of extranodal NK/T-cell lymphoma nasal type but was absent in the other subtypes.

CONCLUSION

Among mature T/NK-cell lymphomas of the oral and maxillofacial region, extranodal NK/T-cell lymphoma, nasal type and peripheral T-cell lymphoma, NOS predominated. Older men were the most affected patients, and this heterogeneous group of neoplasms has a very aggressive clinical behaviour.

Anaplastic large cell lymphoma: Report of two cases with rare patterns (carcinomatous and sarcomatous) in fine needle aspiration cytology and histopathology

Anaplastic large cell lymphoma (ALCL) is a non-Hodgkin lymphoma of T-cell or null-cell lineage with variable cytomorphology. We report two rare ALCL cases with carcinomatous and sarcomatous patterns, respectively, in fine needle aspiration (FNA) cytology and histopathology. The first case was a 56-year-old man with enlarged left inguinal lymph node. FNA smears showed a malignant small round cell tumor with nuclear molding. In addition, there were large bi-nucleated and multinucleated cells with wreath-like arrangement of nuclei. ALCL and small cell (neuroendocrine) carcinoma were the possibilities considered. Immunocytochemical studies on FNA smears showed positive reaction for leukocyte common antigen (LCA) and negative results for cytokeratin (CK) and chromogranin. Histopathological examination of the lymph node showed features of ALCL with following immunohistochemical staining results: LCA+, CD30+, CD45RO+, CD20-, CD3+ (weak), and Alk1-. During review of sections, areas resembling a small cell anaplastic carcinoma were observed. The second case was a 24-year-old woman with right cervical lymphadenopathy. FNA smears showed an ALCL with highly atypical large cells including bi-nucleated and donut shaped cells, which were positive for CD30, EMA, and Alk-1 protein, and negative for CD20, CD3, and CK. Histopathological examination corroborated the cytodiagnosis of ALCL, and with positive immunohistochemical staining for CD30, EMA, Alk-1 protein+, BCL6+, and Ki67+ (40% cells) and negative results for CD20, CD10, CD3, CD5, CD15, BCl2, CD79a, and CD68. Sarcomatous components were noticed during review of cytologic and histopathological specimen. Awareness about these unusual cytomorphological patterns in ALCL may be of help in proper diagnosis of this neoplasm.

Classic Hodgkin lymphoma with initial extranodal osseous presentation: a case report and literature review

Initial extranodal osseous presentation of Classic Hodgkin lymphoma (CHL) is extremely rare. The present study describes a case of CHL in an 11-year-old male presenting with lower back and right hip pain. Radiologic imaging showed a solitary lytic lesion involving the L5 vertebrae and sacrum. Pathologic examination led to a diagnosis of extranodal osseous CHL and further workup proved bone marrow and nodal disease. Diagnosis of extranodal osseous CHL is challenging, especially in this age group and location. When confronted with a solitary lytic bone lesion in a young patient, more common benign and neoplastic entities enter the differential diagnosis and include osteomyelitis, Langerhans cell histiocytosis, epithelioid hemangioma of bone, leukemia, and anaplastic large cell lymphoma (ALCL) among others, with extranodal osseous CHL being one of the less common entities in the differential diagnosis. This case report raises the awareness of extranodal osseous CHL as one of the entities to consider when confronted with a solitary lytic bone lesion in a young patient.

[Hematological neoplasias as differential diagnoses of soft tissue tumors]

BACKGROUND

Several hematological malignancies might morphologically present as differential diagnoses of sarcomas.

OBJECTIVES

To illustrate entities of hematological malignancies that might cause difficulties in differentiation from sarcomas and to introduce immunohistochemical and molecular tests that facilitate the diagnosis.

MATERIAL AND METHODS

Selective literature research ( http://www.ncbi.nlm.nih.gov ) was combined with the clinico-pathological experience of the authors.

RESULTS

In particular, hematologic malignancies with small blue round cell cytology, as well as lymphomas with anaplastic or spindle cell morphology, may mimic sarcomas. Identification of the correct diagnosis is usually possible by applying immunohistochemical and molecular analyses. Lymphomas without expression of CD45 and hematological neoplasias with expression of markers characteristic of sarcomas may cause difficulties in differential diagnosis.

CONCLUSION

Hematological malignancies should be kept in mind as differential diagnoses of sarcomas and should be excluded by immunohistochemical and molecular analyses according to morphology and the clinical picture.

Update on the classification of T-cell lymphomas, Hodgkin lymphomas, and histiocytic/dendritic cell neoplasms

Introduction: The classification of lymphomas is based on the postulated normal counterparts of lymphoid neoplasms and currently constitutes over 100 definite or provisional entities. As this number of entities implies, lymphomas show marked pathological, genetic, and clinical heterogeneity. Recent molecular findings have significantly advanced our understanding of lymphomas. Areas covered: The World Health Organization (WHO) classification of lymphoid neoplasms was updated in 2017. The present review summarizes the new findings that have been gained in the areas of mature T-cell neoplasms, Hodgkin lymphomas, and histiocytic/dendritic cell neoplasms since the publication of the 2017 WHO classification. Expert opinion: Although formal revisions to the WHO classification are published only periodically, our understanding of the pathologic, genetic, and clinical features of lymphoid neoplasms is constantly evolving, particularly in the age of -omics technologies and targeted therapeutics. Even in the relatively short time since the publication of the 2017 WHO classification, many significant findings have been identified in the entities covered in this review.

Histiocytic Sarcoma: Review, Discussion of Transformation From B-Cell Lymphoma, and Differential Diagnosis

Context.—

Histiocytic sarcoma is a rare neoplasm of mature histiocytes with an aggressive clinical course that can arise de novo or from a low-grade B-cell lymphoma. In particular, chronic lymphocytic leukemia/small lymphocytic lymphoma is a very common malignancy in the Western hemisphere, and most cases of chronic lymphocytic leukemia/small lymphocytic lymphoma have an indolent course and behavior. However, 2% to 8% of chronic lymphocytic leukemia/small lymphocytic lymphoma cases transform. Histiocytic sarcomatous transformation is rare and portends poor prognosis.

Objective.—

To review the clinical features, morphology, and key points related to the differential diagnosis for histiocytic sarcoma. We discuss recent understanding of the biology underlying transformation.

Data Sources.—

University of Michigan case and review of pertinent literature about histiocytic sarcoma and morphologic differential diagnosis.

Conclusions.—

Histiocytic sarcoma is a rare histiocytic neoplasm that can arise as a result of transdifferentiation from low-grade B-cell lymphomas, and has a wide differential diagnosis including other histiocytic/dendritic cell neoplasms, myeloid neoplasms, lymphomas, melanoma, and carcinoma. However, some key morphologic and immunohistochemical features allow for accurate classification.

Use of flow cytometry in the phenotypic diagnosis of hodgkin's lymphoma

Hodgkin's lymphoma (HL) has a unique immunophenotype derived from immunohistochemistry (positive for CD15, CD30, and Pax-5; negative for CD3, CD20 in most cases, and CD45). The knowledge gained over recent years enables better diagnosis, prognosis, and treatment of HL. Flow cytometry as a tool for the diagnosis of classic HL has not been useful in the past due to the difficulty in isolating Reed-Sternberg cells as they are admixed in a rich inflammatory background which consists mainly of T cells, B cells, eosinophils, histiocytes, and plasma cells. However, in the recent past, several studies have tried to identify Reed-Sternberg cells using flow cytometry on fine needle aspiration or tissue biopsy of lymph nodes to confirm or supplement immunohistochemistry staining in diagnosis. Newer and more sensitive tools such as flow cytometry can be used for diagnosis, technology that may have been difficult in the past for diagnosis of this lymphoma subtype. Using flow cytometry, diagnosis is faster and could lead to point-of-care technology especially where we have typical immunophenotype signatures. © 2018 International Clinical Cytometry Society.

Diagnosis and classification of lymphoma: Impact of technical advances

Our current understanding of the normal lymphoid system informs the modern classification of lymphomas. B-cell, T-cell, and natural killer-cell neoplasms often recapitulate normal stages of lymphoid cell differentiation and function. Moreover, the clinical manifestations of lymphomas often reflect the normal function of lymphoid cells in vivo. The multiparameter approach to classification adopted by the Revised European and American Lymphoma and subsequent WHO classifications facilitates the interpretation of clinical and translational studies, and provides a framework for the discovery of molecular alterations that drive these tumors. An accurate and precise classification of disease entities facilitates the discovery of the molecular basis of lymphoid neoplasms in the basic science laboratory, and leads to new diagnostic tools that play a role in clinical diagnosis.

The Pathological Spectrum of Systemic Anaplastic Large Cell Lymphoma (ALCL)

Anaplastic large cell lymphoma (ALCL) represents a group of malignant T-cell lymphoproliferations that share morphological and immunophenotypical features, namely strong CD30 expression and variable loss of T-cell markers, but differ in clinical presentation and prognosis. The recognition of anaplastic lymphoma kinase (ALK) fusion proteins as a result of chromosomal translocations or inversions was the starting point for the distinction of different subgroups of ALCL. According to their distinct clinical settings and molecular findings, the 2016 revised World Health Organization (WHO) classification recognizes four different entities: systemic ALK-positive ALCL (ALK+ ALCL), systemic ALK-negative ALCL (ALK− ALCL), primary cutaneous ALCL (pC-ALCL), and breast implant-associated ALCL (BI-ALCL), the latter included as a provisional entity. ALK is rearranged in approximately 80% of systemic ALCL cases with one of its partner genes, most commonly NPM1, and is associated with favorable prognosis, whereas systemic ALK− ALCL shows heterogeneous clinical, phenotypical, and genetic features, underlining the different oncogenesis between these two entities. Recognition of the pathological spectrum of ALCL is crucial to understand its pathogenesis and its boundaries with other entities. In this review, we will focus on the morphological, immunophenotypical, and molecular features of systemic ALK+ and ALK− ALCL. In addition, BI-ALCL will be discussed.

The masquerading presentation of a systemic anaplastic large cell lymphoma, ALK positive: a case report and review of the literature

We report an unusual case of systemic anaplastic large cell lymphoma (ALCL), ALK positive with leukemic involvement in a 57-year-old woman. The patient presented with a fulminant respiratory infection unresponsive to treatment requiring intensive care and ventilatory support. The CT scan demonstrated mediastinal and bilateral lymphadenopathy. On peripheral smear a few atypical lymphocytes were visualized. Based on the increasing number of atypical lymphocytes in the daily peripheral bloodsmears, the diagnosis ALCL was suggested. Definitive diagnosis was made on a bone marrow biopsy, with lymphocytes being immunoreactive for CD30, EMA, and ALK. Leukemic peripheral blood involvement in ALCL is an uncommon clinicopathologic entity with unfavorable prognosis. The case we present is perhaps unusual in that a complete respons was achieved, highlighting the importance of prompt diagnosis and judicious management.

PAX5-Negative Classical Hodgkin Lymphoma: A Case Report of a Rare Entity and Review of the Literature

Classical Hodgkin lymphoma (CHL) is recognized as a B-cell neoplasm arising from germinal center or postgerminal center B-cells. The hallmark of CHL is the presence of CD30 (+) Hodgkin and Reed-Sternberg (HRS) cells with dim expression of PAX5. Nearly all of the HRS cells are positive for PAX5. However, a small minority of HRS cells may lack PAX5 expression, which can cause a diagnostic dilemma. Herein we describe two cases of PAX5-negative CHL and review of the English literature on this very rare entity. It is crucial to be aware of this phenomenon, which in some cases may lead to misdiagnosis and may ultimately adversely affect patient's management.

Adolescent and young adult lymphoma: collaborative efforts toward optimizing care and improving outcomes

Lymphomas are responsible for approximately 20% to 25% of annual cancer diagnoses in the adolescent and young adult (AYA) population. In 2006, the National Cancer Institute and the Lance Armstrong Foundation developed a joint Adolescent and Young Adult Oncology Progress Review Group (AYAO-PRG) to formally address the unique cancer burden of patients age 15 to 39 years. As part of their recommendations, the AYAO-PRG identified 5 imperatives for improving outcomes of AYAs with cancer. Broadly, the recommended areas of focus included research, awareness and education, investigational infrastructure, care delivery, and advocacy. In response to the challenges highlighted by the AYAO-PRG, the Lymphoma Research Foundation held the first AYA Lymphoma Research Foundation Symposium on 2 October 2015. At this symposium, clinicians and basic scientists from both pediatric and adult disciplines gave presentations describing the state of the science and proposed a collaborative research agenda built on the imperatives proposed by the AYAO-PRG. The following review presents an in-depth discussion of lymphoma management across pediatric and adult oncologic disciplines, focusing on Hodgkin lymphoma, mature B-cell lymphomas, and anaplastic large cell lymphoma.

The heterogeneous landscape of ALK negative ALCL

Anaplastic Large Cell Lymphoma (ALCL) is a clinical and biological heterogeneous disease including systemic ALK positive and ALK negative entities. Whereas ALK positive ALCLs are molecularly characterized and readily diagnosed, specific immunophenotypic or genetic features to define ALK negative ALCL are missing, and their distinction from other T-cell non-Hodgkin lymphomas (T-NHLs) can be controversial. In recent years, great advances have been made in dissecting the heterogeneity of ALK negative ALCLs and in providing new diagnostic and treatment options for these patients. A new revision of the World Health Organization (WHO) classification promoted ALK negative ALCL to a definite entity that includes cytogenetic subsets with prognostic implications. However, a further understanding of the genetic landscape of ALK negative ALCL is required to dictate more effective therapeutic strategies specifically tailored for each subgroup of patients.

ALK-positive Large B-cell Lymphoma: A Clinicopathologic Study of 26 Cases With Review of Additional 108 Cases in the Literature

Anaplastic lymphoma kinase-positive large B-cell lymphoma (ALK LBCL) is a rare, aggressive subtype of diffuse large B-cell lymphoma with characteristic ALK rearrangements. Diagnosis of ALK LBCL can be challenging because of its rarity, unique morphologic characteristics, and unusual immunophenotypic features, which significantly overlap with other hematologic and nonhematologic neoplasms. The purpose of this study is to further explore the clinicopathologic features of ALK LBCL to ensure the awareness and accurate diagnosis of this entity. We retrospectively reviewed the data from 26 cases in our institutions and additional 108 cases from the literature. ALK LBCL typically occurred in the lymph nodes of young and middle-aged, immunocompetent patients. The medium age was 35 years with a male to female ratio of 3.5:1. Vast majority of cases showed immunoblastic and/or plasmablastic morphology. All cases expressed ALK protein with a cytoplasmic granular pattern in most of them. Common B-cell markers (CD20, CD79a, and PAX5) were typically negative, but the tumor cells mostly expressed 2 B-cell transcriptional factors, BOB1 and OCT2. The 5-year overall survival (OS) was 34%, and the median survival was 1.83 years. In patients with stage III/IV disease, the 5-year OS was only 8%. Moreover, patients below 35 years of age had a significantly better OS than those aged 35 years or above.

Diagnosis and classification of hematologic malignancies on the basis of genetics

Genomic analysis has greatly influenced the diagnosis and clinical management of patients affected by diverse forms of hematologic malignancies. Here, we review how genetic alterations define subclasses of patients with acute leukemias, myelodysplastic syndromes (MDS), myeloproliferative neoplasms (MPNs), non-Hodgkin lymphomas, and classical Hodgkin lymphoma. These include new subtypes of acute myeloid leukemia defined by mutations in RUNX1 or BCR-ABL1 translocations as well as a constellation of somatic structural DNA alterations in acute lymphoblastic leukemia. Among patients with MDS, detection of mutations in SF3B1 define a subgroup of patients with the ring sideroblast form of MDS and a favorable prognosis. For patients with MPNs, detection of the BCR-ABL1 fusion delineates chronic myeloid leukemia from classic BCR-ABL1^- MPNs, which are largely defined by mutations in JAK2, CALR, or MPL In the B-cell lymphomas, detection of characteristic rearrangements involving MYC in Burkitt lymphoma, BCL2 in follicular lymphoma, and MYC/BCL2/BCL6 in high-grade B-cell lymphomas are essential for diagnosis. In T-cell lymphomas, anaplastic large-cell lymphoma is defined by mutually exclusive rearrangements of ALK, DUSP22/IRF4, and TP63 Genetic alterations affecting TP53 and the mutational status of the immunoglobulin heavy-chain variable region are important in clinical management of chronic lymphocytic leukemia. Additionally, detection of BRAFV600E mutations is helpful in the diagnosis of classical hairy cell leukemia and a number of histiocytic neoplasms. Numerous additional examples provided here demonstrate how clinical evaluation of genomic alterations have refined classification of myeloid neoplasms and major forms of lymphomas arising from B, T, or natural killer cells.

Clinical Significance of TIPE2 Protein Upregulation in Non-Hodgkin's Lymphoma

Non-Hodgkin's lymphoma (NHL), which includes diffuse large B-cell lymphoma (DLBCL) and peripheral T-cell lymphoma, is a refractory malignant tumor originated from the lymphatic system. TNFAIP8L2 (TIPE2 or tumor necrosis-alpha-induced protein-8 like 2) is a negative regulator for inflammation and an inhibitor for carcinogenesis. However, whether TIPE2 plays a role in lymphomagenesis is unknown. In this study, we determined TIPE2 expression in NHL by immunohistochemistry and investigated its clinicopathological significance in DLBCL. We found that TIPE2 expression was upregulated in both DLBCL and peripheral T-cell lymphoma. But the expression of TIPE2 in T lymphomas was weaker than that in DLBCL. Interestingly, among DLBCL, TIPE2 expression was significantly stronger in the germinal center B-cell (GCB) type than in the non-GCB type. These results suggest that the expression of TIPE2 protein could be a predictor of better prognosis for DLBCL.

Expression of p63 protein in anaplastic large cell lymphoma: implications for genetic subtyping

Anaplastic large cell lymphomas (ALCLs) are CD30-positive T-cell non-Hodgkin lymphomas that bear chromosomal rearrangements of the TP53 homologue TP63 in a subset of cases that demonstrate aggressive clinical behavior. In the present study, we examined the relationship between p63 protein expression by immunohistochemistry and the results of fluorescence in situ hybridization using TP63 probes in 116 ALCLs. We also determined the relative expression of full-length TAp63 and truncated ΔNp63 isoforms (eg, p40) in ALCL cell lines and a subset of clinical cases. Overall, 35.3% of ALCLs were positive for p63 protein. Primary cutaneous and anaplastic lymphoma kinase-negative ALCLs were positive more frequently than anaplastic lymphoma kinase-positive ALCLs (P=.0034). As previously reported, cases with TP63 gene rearrangements expressed p63 uniformly. p63 expression in nonrearranged cases was associated with extra copies of TP63 on 3q28 (P<.0001). Extra copies of TP63 correlated with extra copies of the DUSP22 locus on 6p25.3 (P<.0001). Results of immunohistochemistry, Western blotting, and RNA sequencing indicated that p63 expression in nonrearranged cases was entirely attributable to TAp63 isoforms. Taken together, these findings indicate that ALCLs without TP63 rearrangements may express TAp63 isoforms of p63 and that this expression is associated with extra copies of TP63, probably due to widespread genomic copy number abnormalities rather than focal gains. Immunohistochemistry for p63 in ALCL is not specific for TP63 rearrangements but is useful clinically as a screening test to select cases for further testing by fluorescence in situ hybridization. Immunohistochemistry for ΔNp63 (p40) is not informative in the evaluation of ALCL.

Lymphoma classification update: T-cell lymphomas, Hodgkin lymphomas, and histiocytic/dendritic cell neoplasms

INTRODUCTION

Lymphomas are classified based on the normal counterpart, or cell of origin, from which they arise. Because lymphocytes have physiologic immune functions that vary both by lineage and by stage of differentiation, the classification of lymphomas arising from these normal lymphoid populations is complex. Recent genomic data have contributed additional depth to this complexity. Areas covered: Lymphoma classification follows the World Health Organization (WHO) system, which reflects international consensus and is based on pathological, genetic, and clinical factors. The present review focuses on the classification of T-cell lymphomas, Hodgkin lymphomas, and histiocytic and dendritic cell neoplasms, summarizing changes reflected in the 2016 revision to the WHO classification. These changes are critical to hematologists and other clinicians who care for patients with these disorders. Expert commentary: Lymphoma classification is a continually evolving field that needs to be responsive to new clinical, pathological, and molecular understanding of lymphoid neoplasia. Among the entities covered in this review, the 2016 revisions in the WHO classification particularly impact T-cell lymphomas, including a new umbrella category of T-follicular helper cell-derived lymphomas and evolving recognition of indolent T-cell lymphomas and lymphoproliferative disorders.

The Microscope as a Tool for Disease Discovery-A Personal Voyage

This review reflects the trajectory of my career in hematopathology, and my personal reflections on scientific advances in the field. During the course of more than 40 years, the approach to classification of hematological malignancies has evolved from descriptive approaches, based on either cytological or clinical features, to a modern approach, which incorporates cutting-edge technologies. My philosophy has focused on defining individual diseases, an approach that can best lead to an understanding of molecular pathogenesis. To quote Carolus Linnaeus ( 1 , p. 19), the father of taxonomy, "The first step in wisdom is to know the things themselves; this notion consists in having a true idea of the objects; objects are distinguished and known by classifying them methodically and giving them appropriate names. Therefore, classification and name-giving will be the foundation of our science."

Anaplastic large cell lymphoma: A great mimic on cytology

Anaplastic large cell lymphoma (ALCL) is a T-cell lymphoma, accounting for <5% of non-Hodgkin's lymphoma. Cutaneous involvement can be primary or secondary arising in systemic ALCL. The diagnostic feature in both is the presence of pleomorphic, CD30 positive hallmark cells. We present a case of ALCL in a 19-year-old male presenting as an ulcerated scalp swelling. Clinical impression was actinomycosis or scrofuloderma. Cytology smears showed large dispersed pleomorphic cells with hyperlobated nuclei and multinucleated giant cells. The differentials considered were ALCL, rhabdomyosarcoma, and poorly differentiated carcinoma. Immunocytochemistry (ICC) showed positivity for leukocyte common antigen (LCA) and CD30 while negativity for desmin, favoring ALCL. Computed tomography (CT) showed a lytic paravertebral lesion. Subsequently, both paraspinal and scalp lesions were biopsied and immunochemistry confirmed the diagnosis of ALCL. Thus, cutaneous involvement in ALCL can resemble inflammatory and other neoplastic lesions clinically and cytologically. Hence, a high index of suspicion and ICC can aid in the correct diagnosis on fine needle aspiration cytology (FNAC).

PAX-5 Positivity in Anaplastic Lymphoma Kinase-Negative Anaplastic Large Cell Lymphoma: A Case Report and Review of Literature

Anaplastic lymphoma kinase (ALK)-negative anaplastic large cell lymphoma (ALCL) is a subtype of T-cell lymphomas that may mimic several other malignancies morphologically. With the help of immunohistochemistry, most cases of ALCL can be diagnosed on the basis of expression of T-cell lineage associated antigens. However, aberrations in the expression of immunohistochemical markers pose diagnostic challenges. The morphological and immunophenotypic features of ALCL show considerable overlap with classical Hodgkin lymphoma (CHL), which is a B-cell lymphoma. The 2008 World Health Organization Classification of Tumours of Haematopoietic and Lymphoid Tissues suggests that staining for the B-cell transcription factor, paired box 5 (PAX-5), is helpful in differentiating between them, as it is weakly positive in most CHL and should be negative in ALCL. We report a rare case of ALK-negative ALCL, which was positive for PAX-5 and CD15, mimicking CHL by immunohistochemistry, resulting in a diagnostic dilemma.

Transformation of CLL to ALCL: the role of clonality studies in diagnostic molecular haematopathology

Clonality studies greatly assist in the diagnosis of challenging haematopathology cases. These robust and standardised tests aid the detection of clonal lymphoid populations and may assist in lymphocyte subtyping. In this case report, a gentleman presented with a high-grade transformation of a B cell neoplasm which histologically and immunophenotypically mimicked a T cell anaplastic large-cell lymphoma. With the aid of T cell and B cell receptor clonality studies, it was demonstrated that this tumour was in fact of B cell lineage. This report exemplifies the role of these increasingly used and relatively new molecular tests in unusual and difficult lymphoma presentations and highlights potential pitfalls in the interpretation of their results.

Fine-needle aspiration cytology yield as a basis for morphological, molecular, and cytogenetic diagnosis in alk-positive anaplastic large cell lymphoma with atypical clinical presentation

ALK positive anaplastic large cell lymphoma is a T-cell lymphoma usually occurring in children and young adults. It frequently involves lymph nodes and extranodal sites and is associated with favorable prognosis. A 20-year old man was admitted for painful mass in the left axilla with overlying skin redness. Clinical presentation and US findings were highly suspicious for sarcoma. Definitive diagnosis was established cytolologically and using ancillary technologies from cytological samples. Fine needle aspiration cytology of tumor mass (lymph node conglomerate and surrounding tissue) show predominance of large, pleomorphic, atypical cells with large nuclei and vacuolised cytoplasm. Atypical cells immunocytochemically were positive for LCA, CD30, CD3, EMA, and ALK; negative for CD15 and CD56. NPM-ALK transcript was detected by reverse transcriptase-polymerase chain reaction (RT-PCT). Molecular analysis of TCRß and TCRγ genes demonstrated clonal TCR genes rearrangement. Complex karyotype with multiple numerical and structural changes was found on conventional cytogenetics. These findings excluded sarcoma and corroborated the diagnosis of ALK positive ALCL. Cutaneous involvement in ALCL can clinically mimic sarcoma, especially in cases with localized disease without B symptoms. In those cases, immunostaining, PCR, and conventional cytogenetics are helpful to exclude sarcoma. Diagn. Cytopathol. 2017;45:51-54. © 2016 Wiley Periodicals, Inc.

Integrated mate-pair and RNA sequencing identifies novel, targetable gene fusions in peripheral T-cell lymphoma

Peripheral T-cell lymphomas (PTCLs) represent a heterogeneous group of T-cell malignancies that generally demonstrate aggressive clinical behavior, often are refractory to standard therapy, and remain significantly understudied. The most common World Health Organization subtype is PTCL, not otherwise specified (NOS), essentially a "wastebasket" category because of inadequate understanding to assign cases to a more specific diagnostic entity. Identification of novel fusion genes has contributed significantly to improving the classification, biologic understanding, and therapeutic targeting of PTCLs. Here, we integrated mate-pair DNA and RNA next-generation sequencing to identify chromosomal rearrangements encoding expressed fusion transcripts in PTCL, NOS. Two of 11 cases had novel fusions involving VAV1, encoding a truncated form of the VAV1 guanine nucleotide exchange factor important in T-cell receptor signaling. Fluorescence in situ hybridization studies identified VAV1 rearrangements in 10 of 148 PTCLs (7%). These were observed exclusively in PTCL, NOS (11%) and anaplastic large cell lymphoma (11%). In vitro, ectopic expression of a VAV1 fusion promoted cell growth and migration in a RAC1-dependent manner. This growth was inhibited by azathioprine, a clinically available RAC1 inhibitor. We also identified novel kinase gene fusions, ITK-FER and IKZF2-ERBB4, as candidate therapeutic targets that show similarities to known recurrent oncogenic ITK-SYK fusions and ERBB4 transcript variants in PTCLs, respectively. Additional novel and potentially clinically relevant fusions also were discovered. Together, these findings identify VAV1 fusions as recurrent and targetable events in PTCLs and highlight the potential for clinical sequencing to guide individualized therapy approaches for this group of aggressive malignancies.

Adult systemic anaplastic large-cell lymphoma: recommendations for diagnosis and management

Systemic anaplastic large-cell lymphomas (sALCLs) comprise a heterogeneous group of relatively rare T-cell non-Hodgkin lymphomas (NHLs) characterized by CD30 expression and other unifying pathologic features. Anaplastic lymphoma kinase (ALK) fusions are present in about 50% of cases. Pathological diagnosis can be challenging, particularly in ALK-negative cases. Though ALK-positive and ALK-negative sALCLs are similar morphologically and immunophenotypically, they are separate entities with different genetics, clinical behavior, and outcomes. Evidence-based data evaluating treatment regimens are limited as randomized controlled trials are lacking and most prospective studies are too small to draw definitive conclusions. However, recent advances in molecular biology are bringing forth much-needed knowledge in this field, and are likely to guide further targeted therapeutic development.

Identification of a new subclass of ALK-negative ALCL expressing aberrant levels of ERBB4 transcripts

Anaplastic large-cell lymphoma (ALCL) is a clinical and biological heterogeneous disease that includes systemic anaplastic lymphoma kinase (ALK)-positive and ALK-negative entities. To discover biomarkers and/or genes involved in ALK-negative ALCL pathogenesis, we applied the cancer outlier profile analysis algorithm to a gene expression profiling data set including 249 cases of T-cell non-Hodgkin lymphoma and normal T cells. Ectopic coexpression of ERBB4 and COL29A1 genes was detected in 24% of ALK-negative ALCL patients. RNA sequencing and 5' RNA ligase-mediated rapid amplification of complementary DNA ends identified 2 novel ERBB4-truncated transcripts displaying intronic transcription start sites. By luciferase assays, we defined that the expression of ERBB4-aberrant transcripts is promoted by endogenous intronic long terminal repeats. ERBB4 expression was confirmed at the protein level by western blot analysis and immunohistochemistry. Lastly, we demonstrated that ERBB4-truncated forms show oncogenic potentials and that ERBB4 pharmacologic inhibition partially controls ALCL cell growth and disease progression in an ERBB4-positive patient-derived tumorgraft model. In conclusion, we identified a new subclass of ALK-negative ALCL characterized by aberrant expression of ERBB4-truncated transcripts carrying intronic 5' untranslated regions.

Anaplastic large cell lymphoma occurring in women with breast implants: analysis of 173 cases

BACKGROUND

The first silicone breast implant was inserted in 1962. In 1997, the first case of anaplastic large cell lymphoma (ALCL) in association with a silicone breast implant was reported. The authors reviewed 37 articles in the world literature reporting on 79 patients and collected another 94 unreported cases as of the date of submission.

METHODS

The world literature was reviewed. Missing clinical and laboratory information was solicited from the authors and treating physicians. As several different specialties were involved, information was not in one place. Many (but not all) authors and treating physicians were responsive, resulting in incomplete data.

RESULTS

ALCL lesions first presented as late peri-implant seromas, a mass attached to the capsule, tumor erosion through the skin, in a regional node, or discovered during revision surgery. The clinical course varied widely from a single positive cytology result followed by apparent spontaneous resolution, to disseminated treatment-resistant tumor and death. There was no preference for saline or silicone fill or for cosmetic or reconstructive indications. Where implant history was known, the patient had received at least one textured-surface device. Extracapsular dissemination occurred in 18 cases; nine of those were fatal. Histochemical markers were primarily CD-30 and Alk-1. Other markers occurred at a lower frequency. Risk estimates ranged from one in 500,000 to one in 3 million women with implants.

CONCLUSION

Breast implant-associated ALCL is a novel manifestation of site- and material-specific lymphoma originating in a specific scar location, presenting a wide array of diverse characteristics and suggesting a multifactorial cause.

Anaplastic large cell lymphoma: features presenting diagnostic challenges

Anaplastic large cell lymphoma has histopathologic features that necessitate a broad differential diagnosis. Diagnostic considerations include carcinoma, melanoma, and hematopoietic malignancies, including diffuse large B-cell lymphoma, classical Hodgkin lymphoma, myeloid sarcoma, and peripheral T-cell lymphoma, not otherwise specified. Unusual features can include subtle sinusoidal involvement, histiocytic morphology, cytokeratin expression, CD15 expression, and variant patterns of anaplastic lymphoma kinase expression. Cases with unusual morphologic or immunohistochemical findings will be presented to highlight the complexity encountered in practice.

Expression of KLF4 is a predictive marker for survival in pediatric Burkitt lymphoma

Krüppel-like factor 4 (KLF4) is expressed in a variety of tissues with diverse physiological functions and activities. KLF4 can also function as a tumor suppressor or an oncogene, depending on the cellular context. Its role in hematological malignancies is controversial. This study examined the expression levels of KLF4 by immunohistochemistry in 73 pediatric non-Hodgkin lymphomas (NHLs) in a tissue microarray and also on several B-NHL cell lines. Elevated levels of KLF4 expression were detected in 66% of lymphoma cases and were more frequent in the Burkitt lymphoma (p = 0.05) subtype. There was a significant predictive power for outcome with low KLF4 expression, predicting a favorable overall survival compared to high levels. Multivariate analyses confirmed the association of KLF4 expression with unfavorable overall survival (p < 0.005). These findings were consistent with analyses in existing NHL microarray datasets. The present findings revealed that KLF4 is overexpressed in Burkitt pediatric lymphoma and is a potential biomarker for inferior overall survival.

Unusual clinical presentation of anaplastic large cell lymphoma

Anaplastic large cell lymphoma (ALCL), a well-recognized entity, presents a varied clinical picture and epidemiological characteristics associated with the expression of the anaplastic lymphoma kinase (ALK) protein. When classic symptoms are present (weight loss, fever, and night sweats) and combine with enlarged and easily accessible peripheral lymph nodes, diagnosis is not that difficult. But when the clinical presentation is nonspecific, a tough diagnostic task is required. HIV infection is highly associated with neoplastic disorders-mainly with those of hematological origin. However, ALCL is exceptionally associated with HIV infection, and the few reported cases are ALK- ALCL. The authors report two cases of ALK+ ALCL with the unusual clinical presentation: one is associated with the HIV infection and the other presents as a fever of unknown origin (FUO) without peripheral lymphadenopathy. The latter was autopsied and was characterized by nodal and extra nodal involvement. The authors call attention to the plurality of clinical presentation of this group of lymphomas, and the early indication of bone marrow examination in cases of an FUO with elevated hepatic enzymes and lactic dehydrogenase.

Aberrant expression of CD56 by circulating Sézary syndrome malignant T lymphocytes

Sézary syndrome (SS) is an aggressive variant of cutaneous T cell lymphoma characterized by the presence of malignant T cells in the skin, peripheral blood and lymph nodes. The tumoral population typically displays a CD3⁺ CD4⁺ CD45RO⁺ memory T cell phenotype. We report a case of SS with an aberrant CD56⁺ immunophenotype. This patient presented with a generalized erythroderma and palpable small axillary lymph nodes. SS (stage IVA) was diagnosed on histological criteria and by the detection of a major T cell clone in skin and blood, an elevated CD4/CD8 T cell ratio and Sézary cells count > 1000/mm³. Beside the Sézary cell marker KIR3DL2, immunostainings revealed that two third of the malignant cells expressed CD56 but no other natural killer (NK) cell marker such as CD16, CD160 or NKp46. This atypical expression was not linked to an activation-dependent process and remained stable during the time course of the disease. No loss of the pan T-cell markers CD2, CD3 or CD4 was detected while a complete down-modulation of CD26 was observed. Despite several lines of treatment, no durable amelioration was observed and patient died after 10 mo of follow-up. Because this CD4⁺ CD56⁺ SS case is the only one reported so far, the functional significance of CD56 expression remained difficult to assess in terms of aggressiveness and prognosis.

Is galectin-3 antibody a useful marker in the diagnosis of malignant pleural mesothelioma?

Malignant pleural mesothelioma (MPM) is a challenging diagnosis characterized by the absence of real specific diagnostic markers. Positivity with the galectin-3 antibody was assessed by a cytoplasmic expression in 17 MPM. Fourteen cases expressed the galectin-3 antibody. The three negative cases consisted of epithelioid, biphasic, and sarcomatoid MPM. The 14 positive cases consisted of epithelioid MPM in 12 cases, sarcomatoid MPM in one case, and biphasic MPM in one case. In spite of our inability to prove the real diagnostic value of the galectin-3 antibody, our findings make us wonder about the implication of this antibody in the carcinogenesis of MPM.