A New Subtype of Large B-Cell Lymphoma Expressing the ALK Kinase and Lacking the 2; 5 Translocation

ALK-positive large B-cell lymphoma (ALK + LBCL) with aberrant CD3 expression

ALK-positive ( +) large B cell lymphoma (ALK + LBCL) is a rare distinct subtype of diffuse large B cell lymphoma presenting with high stage and aggressive behavior. Although B cell markers such as CD20, CD19, and CD22 are generally negative, plasmacytic markers including CD138, CD38, and MUM1 are positive. T cell markers are negative with rare exceptions. We report an unusual case of ALK1 + LBCL in a 58-year-old man with partial expression of CD3 without other T cell antigen expression. The tissue was evaluated with flow cytometry, immunohistochemistry, fluorescent in situ hybridization, and gene rearrangement studies. Gene rearrangement studies for IGH and TCR gamma were performed. Flow cytometry did not demonstrate any abnormal lymphoid populations. Tissue sectioning shows a malignant plasmacytic large cell neoplasm which expresses CD45 but is negative for CD20, CD79a, and PAX5. Plasmacytic markers CD138 and MUM1 are positive with kappa light chain restriction. Strong granular cytoplasmic expression of ALK is present. FISH showing disrupted ALK supports the diagnosis while MYC, BCL6, and BCL2 are intact. Gene rearrangement studies show coexisting IGH and TCR gamma clones; however, the TCR peak was present within a polyclonal background suggesting the disputed cells are likely only a subset of the T cell population. ALK + LBCL can present with an ambiguous immunophenotype, which warrants the use of multiple B cell, T cell, and plasmacytic antibodies. CD3 expression in this entity is rare and of uncertain clinical significance, but warrants further study.

Uncommon spinal involvement of ALK-positive anaplastic large cell lymphoma: A pediatric case report and literature review

Anaplastic large cell lymphoma (ALCL) is a rare variety of non-Hodgkin lymphoma that primarily affects children and young adults and is caused by the fusion of the nucleophosmin 1 and ALK genes, which turns on several signalling pathways. Despite the fact that ALCL frequently affects lymph nodes and extranodal sites, involvement of the central nervous system (CNS) is quite uncommon, with symptoms like pain and fever. The spinal localization may result in neurological impairments. T1WI hypointense lesions with T2WI hyperintensity can be observed on MR images, while bone sequestra can be seen in CT scans. The gold standard for diagnosis is still histology, though. Based on distinctive morphological characteristics, immunohistochemical staining can differentiate ALK-positive ALCL from other ALCLs. The prognosis for ALK-positive ALCL is typically better than ALK-negative ALCL, and treatment options include surgery followed by chemotherapy. ALK inhibitors and CAR-T cell therapy are 2 newly developed targeted treatments that have the potential to improve results. This case report illustrates the rarity of CNS ALCL and the difficulties in diagnosis and treatment by describing a 16-year-old female patient with ALCL affecting the thoracic spine and spreading to the mediastinum and surrounding tissue.

TFG::ALK fusion in ALK positive large B-cell lymphoma: a case report and review of literature

Anaplastic lymphoma kinase (ALK) positive large B-cell lymphoma (ALK+ LBCL) is an aggressive and rare subtype of B-cell lymphoma. Patients typically present with advanced clinical stage disease and do not respond to conventional chemotherapy; the median overall survival is 1.8 years. The genetic landscape of this entity remains poorly understood. Here we report a unique case of ALK+ LBCL harbouring a rare TFG::ALK fusion. Targeted next-generation sequencing showed no significant single nucleotide variants, insertions/deletions, or other structural variants beyond the TFG::ALK fusion; deep deletions of FOXO1, PRKCA, and the MYB locus were also detected. Our case report draws attention to this rare disease, highlights a need for larger genetic profiling studies, and focuses on the pathogenesis and potential therapeutic targets of this aggressive disease. To our knowledge, this is the first report of a TFG::ALK fusion in ALK+ LBCL.

Anaplastic Lymphoma Kinase Positive Large B-Cell Lymphoma: Diagnostic Perils and Pitfalls, an Underrecognized Entity

Anaplastic lymphoma kinase (ALK) positive large B-cell lymphoma (ALK+ LBCL) is an extremely uncommon non-Hodgkin lymphoma (NHL) with a distinctive histomorphologic, immunophenotypic and cytogenetic profile. It is unlike the more common ALK-positive anaplastic large cell lymphoma, although the latter shares the ALK rearrangement pathognomonic for this entity. ALK+ LBCL is an underrecognized entity since it is rare and unfamiliar, and shares morphologic and immunohistochemical features with a variety of other neoplasms that can result in misdiagnosis. This lymphoma exhibits plasmacytoid morphology and negativity for classical immunomarkers of B- and T-cell lineages, and CD30; however, it expresses terminally differentiated B-cell/plasma cell markers such as CD38, CD138, and MUM-1. Precise identification of this entity is pivotal because of its aggressive behaviour, poor response to standard chemotherapy regimens and the potential for the development of novel targeted therapy. A high index of suspicion on morphology and an extensive immunohistochemistry armoury are required for the veracious detection of this lymphoma, especially at extranodal sites. The purpose of bringing forth this present case, an extranodal neoplasm with plasmacytoid morphology at vertebral location in a young adult, is to highlight the diagnostic perils and pitfalls, the clues to unravel the quandaries and thus, the incredible utility of histopathological examination and immunohistochemical analysis in attaining the unerring diagnosis.

Anaplastic Lymphoma Kinase positive large B cell lymphoma of ileocaecal mesentery: A case report

ALK+ large B cell lymphoma (LBCL) is a very rare aggressive neoplasm. It accounts for less than 1% of diffuse large B cell lymphoma (DLBCL). This is a case report of ALK+ DLBCL in a 34-year-old woman with an ileocaecal mesenteric mass. Microscopically, the neoplastic cells were of high grade along with a spindle cell component. Immunohistochemistry revealed ALK+, MUM-1+, LCA+, Vimentin+, EMA+ and negative for CK 20, CK 7, neuroendocrine, melanocytic, muscle specific, and GIST panel markers. This case report, hence, presents the rarity of this tumor.

Molecular Update and Evolving Classification of Large B-Cell Lymphoma

Simple Summary

The development of high-throughput technologies in recent years has increased our understanding of the molecular complexity of lymphomas, providing new insights into the pathogenesis of large B-cell neoplasms and identifying different molecular biomarkers with prognostic impact, that lead to the revision of the World Health Organization consensus classification of lymphomas. This review addresses the main histopathological and molecular features of large B-cells lymphomas, providing an overview of the main recent novelties introduced by the last update of the consensus classification.

Abstract

Diffuse large B-cell lymphomas (DLBCLs) are aggressive B-cell neoplasms with considerable clinical, biologic, and pathologic diversity. The application of high throughput technologies to the study of lymphomas has yielded abundant molecular data leading to the identification of distinct molecular identities and novel pathogenetic pathways. In light of this new information, newly refined diagnostic criteria have been established in the fourth edition of the World Health Organization (WHO) consensus classification of lymphomas, which was revised in 2016. This article reviews the histopathological and molecular features of the various aggressive B-cell lymphoma subtypes included in the updated classification.

Anaplastic lymphoma kinase-positive large B-cell lymphoma (ALK + LBCL): a systematic review of clinicopathological features and management

Anaplastic lymphoma kinase-positive (ALK+) large B-cell lymphoma (LBCL) is a rare CD20-negative aggressive lymphoma. Given its rarity, data on ALK + LBCL are scarce and limited to case reports and small case series. Our systematic review included 184 unique cases published in the literature and shows that ALK + LBCL can affect individuals at any age, has a male predominance and is not associated with chronic viral infections. The malignant cells express ALK, VS38c, BLIMP-1, EMA, c-MYC, and BOB-1. The STAT3/STAT5, PI3K/AKT, PLCG2, and ERK pathways are important in the pathophysiology of ALK + LBCL. The prognosis of ALK + LBCL is poor with a 5-year survival rate of 28%. Early disease stage is associated with better outcomes. ALK inhibitors and other targeted agents could be of value in the treatment of ALK + LBCL. Additional research is needed to better understand, diagnose and treat ALK + LBCL.

Diagnosis and treatment of pediatric anaplastic lymphoma kinase-positive large B-cell lymphoma: A case report

BACKGROUND

Anaplastic lymphoma kinase-positive (ALK+) large B-cell lymphoma (LBCL) is a rare type of lymphoma with high invasiveness and rapid progression. It occurs in all age groups, but is extremely rare in children. The lesions mainly involve the lymph nodes and may present with extra-nodal involvement. Response to conventional chemotherapies and local radiotherapy is poor, with a 5-year overall survival of less than 40%. Recently, the use of ALK inhibitors for the treatment of this disease has been reported.

CASE SUMMARY

We present a case of a 12-year-old boy diagnosed with ALK+LBCL. The patient had a 2-mo medical history of a calvarial mass, extensive systemic involvement, and positive bone marrow clathrin heavy chain (CLTC)-ALK fusion gene. Complete remission 1 (CR1) was achieved using the modified LMB89 Group C regimen followed by autologous stem cell transplantation. The patient relapsed 3 mo later. He then achieved CR2 with three short courses of chemotherapy (COP, reduced-dose ICE, low-dose Ara-c+VP16) and continuous alectinib targeted therapy. Afterward, allogeneic hematopoietic stem cell transplantation (allo-HSCT) was performed. At 16 mo after the allo-HSCT, the patient was still in CR2.

CONCLUSION

The modified LMB89 Group C regimen and ALK inhibitors are effective. Allo-HSCT should be performed after remission.

NPM-ALK: A Driver of Lymphoma Pathogenesis and a Therapeutic Target

Simple Summary

Anaplastic lymphoma kinase (ALK) is a tyrosine kinase associated with Anaplastic Large Cell lymphoma (ALCL) through oncogenic translocations mainly NPM-ALK. Chemotherapy is effective in ALK(+) ALCL patients and induces remission rates of approximately 80%. The remaining patients do not respond to chemotherapy and some patients have drug-resistant relapses. Different classes of ALK tyrosine kinase inhibitors (TKI) are available but used exclusively for EML4-ALK (+) lung cancers. The significant toxicities of most ALK inhibitors explain the delay in their use in pediatric ALCL patients. Some ALCL patients do not respond to the first generation TKI or develop an acquired resistance. Combination therapy with ALK inhibitors in ALCL is the current challenge.

Abstract

Initially discovered in anaplastic large cell lymphoma (ALCL), the ALK anaplastic lymphoma kinase is a tyrosine kinase which is affected in lymphomas by oncogenic translocations, mainly NPM-ALK. To date, chemotherapy remains a viable option in ALCL patients with ALK translocations as it leads to remission rates of approximately 80%. However, the remaining patients do not respond to chemotherapy and some patients have drug-resistant relapses. It is therefore crucial to identify new and better treatment options. Nowadays, different classes of ALK tyrosine kinase inhibitors (TKI) are available and used exclusively for EML4-ALK (+) lung cancers. In fact, the significant toxicities of most ALK inhibitors explain the delay in their use in ALCL patients, who are predominantly children. Moreover, some ALCL patients do not respond to Crizotinib, the first generation TKI, or develop an acquired resistance months following an initial response. Combination therapy with ALK inhibitors in ALCL is the current challenge.

Lenalidomide demonstrates clinical activity in anaplastic lymphoma kinase-positive large B-cell lymphoma

Anaplastic lymphoma kinase-positive large B-cell lymphoma (ALK+ LBCL) is known to be a rare and aggressive form of lymphoma that relapses quickly after both conventional chemotherapy and more targeted therapy. Lenalidomide is an immunomodulator that has shown safety and efficacy in multiple myeloma and is also approved for use in several types of lymphoma. In the case described here, the patient had a significant partial response to lenalidomide, which has not previously been described in this type of lymphoma. Given how aggressive and difficult to treat ALK+ LBCL is, further research is warranted to more completely elucidate the mechanism of action of lenalidomide in ALK+ LBCL and its role in treatment.

Approach to nodal-based T-cell lymphomas

Peripheral T-cell lymphomas (PTCLs) represent a heterogeneous group of uncommon malignancies derived from mature T cells and usually characterised by an aggressive clinical course. Their clinical presentation, localisation and pattern of dissemination are highly variable, but the majority of cases present as nodal diseases. The recently revised classification of lymphomas has incorporated many new molecular genetic data derived from gene expression profiling and next generation sequencing studies, which refine the definition and diagnostic criteria of several entities. Nevertheless, the distinction of PTCL from various reactive conditions, and the diagnosis of PTCL subtypes remains notably challenging. Here, an updated summary of the clinicopathological and molecular features of the most common nodal-based PTCLs (angioimmunoblastic T-cell lymphoma and other nodal lymphomas derived from follicular T helper cells, anaplastic large cell lymphomas and peripheral T-cell lymphoma, not otherwise specified) is presented. Practical recommendations in the diagnostic approach to nodal T-cell lymphoproliferations are presented, including indications for the appropriate use and interpretation of ancillary studies. Finally, we discuss commonly encountered diagnostic problems, including pitfalls and mimics in the differential diagnosis with various reactive conditions, and the criteria that allow proper identification of distinct PTCL entities.

Diffuse large B-cell lymphoma variants: an update

Diffuse large B-cell lymphoma (DLBCL) is the most common type of lymphoma, representing approximately one-third of all cases worldwide. In the World Health Organization (WHO) classification of lymphomas, most cases of DLBCL are designated as not otherwise specified (NOS). About 20% of cases, however, are designated as specific variants of DLBCL. These variants, 13 in total, are specified on the basis of distinctive morphological or immunophenotypic findings or distinctive biological or clinical issues associated with their diagnoses. In this review we discuss the following variants: T-cell/histiocyte-rich large B-cell lymphoma; ALK-positive large B-cell lymphoma; plasmablastic lymphoma; intravascular large B-cell lymphoma; large B-cell lymphoma with IRF4 rearrangement; primary mediastinal large B-cell lymphoma; primary cutaneous diffuse large B-cell lymphoma, leg type; primary diffuse large B-cell lymphoma of the central nervous system; diffuse large B-cell lymphoma associated with chronic inflammation; lymphomatoid granulomatosis; primary effusion lymphoma; and HHV8-positive diffuse large B-cell lymphoma, NOS. Two additional variants recognised in the WHO classification, EBV-positive diffuse large B-cell lymphoma and EBV-positive mucocutaneous ulcer are discussed elsewhere in another review within this issue of Pathology. Although not recognised as a specific variant in the current WHO classification, primary testicular diffuse large B-cell lymphoma also has unique biological features and requires some modification of the standard treatment approach for patients with DLBCL. Therefore, we suggest that primary testicular diffuse large B-cell lymphoma also should be recognised as a specific variant of DLBCL in a future version of the WHO classification.

Atypical juvenile histiocytosis with novel KIF5B-ALK gene fusion mimicking subglottic hemangioma

Juvenile Xanthograuloma (JXG) is part of a diverse set of rare histiocytic disorders marked by infiltration of tissues with neoplastic myelomonocytic-derived cells. Molecular analysis has yielded new insights into the classification and management of histiocytic diseases. A three-year-old presented with atypical croup due to a localized subglottic histiocytic lesion mimicking subglottic hemangioma. The lesion was removed via tracheofissure. Pathology revealed a JXG-like histopathology with a rare KIF5B-ALK fusion gene. This is the first isolated ALK-positive lesion to be reported in this location. The discovery of the new ALK-positive subclass of histiocytosis has opened the door for targeted monoclonal ALK inhibition.

Primary Cutaneous Anaplastic Lymphoma Kinase-Positive Large B-Cell Lymphoma

Large B-cell lymphomas include several subtypes. Recently, anaplastic lymphoma kinase (ALK)-positive large B-cell lymphoma has been delineated as a distinct entity involving mostly lymph nodes and rarely affecting extranodal sites. We describe the first case of a primary cutaneous ALK-positive large B-cell lymphoma in a 48-year-old man with a solitary nodule on the back, and describe the histologic and phenotypic features. Accurate staging confirmed the absence of other lesions, and so surgical excision and postoperative local radiation therapy were initiated and resulted in complete remission. Two years later, extracutaneous spread with involvement of axillary lymph nodes occurred. Complete remission was achieved again by multiagent chemotherapy. Our case demonstrates that a primary cutaneous form of ALK-positive large B-cell lymphoma exists. The immunophenotypic analysis of cutaneous large B-cell lymphomas affecting the skin primarily or secondarily should include the assessment of ALK expression.

Anaplastic lymphoma kinase fusions: Roles in cancer and therapeutic perspectives

Receptor tyrosine kinase (RTK) anaplastic lymphoma kinase (ALK) serves a crucial role in brain development. ALK is located on the short arm of chromosome 2 (2p23) and exchange of chromosomal segments with other genes, including nucleophosmin (NPM), echinoderm microtubule-associated protein-like 4 (EML4) and Trk-fused gene (TFG), readily occurs. Such chromosomal translocation results in the formation of chimeric X-ALK fusion oncoproteins, which possess potential oncogenic functions due to constitutive activation of ALK kinase. These proteins contribute to the pathogenesis of various hematological malignancies and solid tumors, including lymphoma, lung cancer, inflammatory myofibroblastic tumors (IMTs), Spitz tumors, renal carcinoma, thyroid cancer, digestive tract cancer, breast cancer, leukemia and ovarian carcinoma. Targeting of ALK fusion oncoproteins exclusively, or in combination with ALK kinase inhibitors including crizotinib, is the most common therapeutic strategy. As is often the case for small-molecule tyrosine kinase inhibitors (TKIs), drug resistance eventually develops via an adaptive secondary mutation in the ALK fusion oncogene, or through engagement of alternative signaling mechanisms. The updated mechanisms of a variety of ALK fusions in tumorigenesis, proliferation and metastasis, in addition to targeted therapies are discussed below.

B cell alterations during BAFF inhibition with belimumab in SLE

BACKGROUND

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease, which exhibits multiple B cell abnormalities including expanded populations of memory B cells and elevated levels of autoantibodies. Belimumab is a monoclonal antibody targeting the B cell cytokine BAFF (a.k.a. BLyS), approved for the treatment of SLE.

METHODS

In this prospective cohort study, B cells from peripheral blood of 23 SLE patients initiating belimumab treatment and followed longitudinally for up to three years, were assessed using mass cytometry.

FINDINGS

B cells decreased during the study period, with a rapid decrease of both naïve and CD11c⁺CD21^- B cells at the first follow-up visit, followed by a continuous reduction at subsequent follow-ups. In contrast, plasma cells and switched memory B cells remained stable throughout the study. The observed immunological changes correlated with early, but not late, clinical improvements. Moreover, high baseline B cell counts were predictive of failure to attain low disease activity. In summary, our data unveiled both rapid and gradual later therapy-associated alterations of both known and unforeseen B cell phenotypes.

INTERPRETATION

Our results suggest that evaluation of B cell counts might prove useful prior to initiation of belimumab treatment and that early treatment evaluation and discontinuation might underestimate delayed clinical improvements resultant of late B cell changes.

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.

Prognostic Significance of in situ Phenotypic Marker Expression in Diffuse Large B-cell Lymphomas

Diffuse large B-cell lymphomas (DLBCL) are the most common lymphoid malignancies, and encompass all malignant lymphomas characterized by large neoplastic cells and B-cell derivation. In the last decade, DLBCL has been subjected to intense clinical, phenotypic and molecular studies, and were found to represent a heterogeneous group of tumors. These studies suggested new disease subtypes and variants with distinct clinical characteristics, morphologies, immunophenotypes, genotypes or gene expression profiles, associated with distinct prognoses or unique sensitivities to particular therapy regimens. Unfortunately, the reliability and reproducibility of the molecular results remains unclear due to contradictory reports in the literature resulting from small sample sizes, referral and selection biases, and variable methodologies and cut-off levels used to determine positivity. Here, we review phenotypic studies on the prognostic significance of protein expression profiles in DLBCL and reconsider our own retrospective data on 301 primary DLBCL cases obtained on a previously validated tissue microarray in light of powerful statistical methods of determining optimal cut-off values of phenotypic factors for prediction of outcome.

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.

Anaplastic lymphoma kinase-positive large B-cell lymphoma: Clinico-pathological study of 17 cases with review of literature

We retrospectively analysed 17 cases of anaplastic lymphoma kinase-positive large B-cell lymphoma (ALK+, LBCL) according to the morphological, immunohistochemical, molecular and clinical features, using which we intend to elucidate the clinicopathological characteristics of this rare entity. In this study, all cases de facto share common features that defined them as a single entity, and various characteristics may expand the spectrum. Among 15 cases, 60% followed an aggressive clinical course with advanced stage and high IPI scores; the median survival of these patients was only 8 months. An analysis showed that both the IPI score and the Ann Arbor stage were significant prognostic factors. Most patients received a chemotherapy regimen including CHOP, CHOEP, EPOCH, and CVAD, and some also underwent localized radiotherapy. However, ALK+, LBCL cases display a dismal clinical outcome and can only be cured with conventional chemotherapy protocols at the stage of localized disease. Novel front-line intensive chemotherapy regimens should therefore be evaluated in this group of patients.

Cytologic perspectives on neoteric B-cell lymphoproliferative disorders

The 2008 World Health Organization (WHO) classification of hematopoietic and lymphoid tissues has been recently revised, and publication of the updated 2016 version is expected soon. Given that cytopathologists are often involved in the diagnosis of primary, recurrent, and transformed lymphoproliferative disorders, knowledge of updates to the WHO lymphoma classification, including terminology, pathogenesis, ancillary techniques, and targeted therapies is necessary. Herein, we reference the last decade of cytology specific literature for seven newer B-cell disorders and provide illustrative examples of each entity from our files.

Relapsed anaplastic lymphoma kinase-positive large B-cell lymphoma expressed cluster of differentiation 4 and cytokeratin: An initially misdiagnosed case corrected by immunoglobulin κ locus gene rearrangement detection

Anaplastic lymphoma kinase (ALK)-positive large B-cell lymphoma (LBCL) is a rare lymphoma subtype. The present study investigated a refractory nodal ALK-positive LBCL case in a 28-year-old Chinese male. It was initially misdiagnosed as ALK-positive anaplastic large cell lymphoma; however, the patient's lesions relapsed and spread widely following a short remission for chemotherapy and the patient succumbed to the disease 3 months' post-autologous stem cell transplantation; thus, a revision was performed. Histologically, the tumor cells exhibited a characteristic immunoblastic morphology with marked cellular pleomorphism. All lesions shared the same immunoprofiles, including granular cytoplasmic ALK staining patterns and a lack of cell lineage-associated markers, with the exception of cluster of differentiation (CD)45 and CD4. CD30 expression was revealed to be negative and CD138 staining was observed to be positive, additionally, cytokeratin was expressed aberrantly in a relapsed tumor biopsy. Fluorescence in situ hybridization studies demonstrated breakage and extra copies of the ALK gene in ≥30% of cells. Final clarification was provided by the detection of immunoglobulin κ locus (IGK) gene rearrangement in clonality studies [but notimmunoglobulin heavy locus (IGH) and immunoglobulin λ locus (IGL) genes]. This aggressive entity requires distinct modalities of standard treatment, and may be ignored owing to its rarity in routine pathology laboratories. BIOMED-2 polymerase chain reaction assays, including for IGH, IGK and IGL genes, are essential for the detection of gene rearrangement.

Starry Sky Pattern in Hematopoietic Neoplasms: A Review of Pathophysiology and Differential Diagnosis

The starry sky pattern is a distinctive histologic feature wherein a rapidly proliferating hematolymphoid neoplasm contains scattered histiocytes with abundant pale cytoplasm in a background of monomorphic neoplastic cells. The cytoplasm of these histiocytes typically contains cellular remnants, also known as tingible bodies, incorporated through active phagocytosis. Although common and widely recognized, relatively little is known about the pathophysiological underpinnings of the starry sky pattern. Its resemblance to a similar pattern seen in the germinal centers of secondary follicles suggests a possible starting point for understanding the molecular basis of the starry sky pattern and potential routes for its exploitation for therapeutic purposes. In this review, we discuss the historical, pathophysiological, and clinical implications of the starry sky pattern.

Plasmablastic Lymphoma: A Review of Clinicopathologic Features and Differential Diagnosis

Plasmablastic lymphoma (PBL) is a challenging diagnosis given its rarity and lack of expression of markers that are usually used by pathologists in establishing hematopoietic lineage. However, knowledge of the characteristic clinical setting, sites of involvement, and morphologic features of plasmablastic lymphoma can aid in the correct diagnosis of a suspected large cell lymphoma that is negative for B-cell– and T-cell–specific antigens. Herein, we review the clinical and pathologic features of plasmablastic lymphoma with an emphasis on the differential diagnosis of hematolymphoid neoplasms with immunoblastic morphology and/or evidence of plasmacytic differentiation by immunophenotype.

Anaplastic lymphoma kinase positive large B-cell lymphoma: Literature review and report of an endoscopic fine needle aspiration case with tigroid backgrounds mimicking seminoma

Anaplastic lymphoma kinase-positive large B-cell lymphoma (ALK+ LBCL) is a rare distinct type of non-Hodgkin's lymphoma that arises in association with alterations of the ALK gene. This distinct disease entity is typically associated with an aggressive clinical course and appears in light microscopic preparations as a monomorphic population of large, immunoblast-like cells. In this report, we describe a case of ALK+ LBCL diagnosed by transgastric endoscopic ultrasound-guided fine needle aspiration (EUS FNA) of splenic hilar lymph nodes. Modified Giemsa stained direct smears from the FNA sample demonstrated large lesional cells with foamy cytoplasm and macronucleoli admixed with small lymphocytes in tigroid backgrounds, mimicking the cytologic appearance of seminoma. Ancillary immunohistochemical studies subsequently confirmed the diagnosis of ALK+ LBCL with the lesional cells being immunoreactive for CD138, VS38c, MUM1, ALK1, and lambda light chain. The cohesiveness of the cells, the cellular morphology, and the tigroid backgrounds were all pitfalls for accurate diagnosis of this rare specific type of lymphoid malignancy by cytology. To our knowledge this is the first case report detailing the diagnosis of ALK+ LBCL by EUS FNA and the first report describing a glycogen-rich tigroid background in direct FNA smears. Establishing a refined diagnosis in cases of this rare form of LBCL is necessary, as therapies targeting ALK may be of value in clinical management. Diagn. Cytopathol. 2017;45:148-155. © 2016 Wiley Periodicals, Inc.

Primary rare anaplastic large cell lymphoma, ALK positive in small intestine: case report and review of the literature

Background

Primary anaplastic large cell lymphoma, ALK positive in small intestine is clinically rare and the clinical, radiological and pathological information are generally not available. Here, we report a case of 32-year-old male with ALK positive anaplastic large cell lymphoma at the junction of jejunum and ileum, and highlight the clinicopathological features and the differential diagnosis of this type lymphoma.

Case presentation

The patient presented with right middle abdominal mass for 1 month with sporadic pain. Computed tomography (CT) showed a mass measured 8.5 × 7.4 × 4 cm at the junction of jejunum and ileum. The diagnosis was made after pathological examination of the excised tissue by enterectomy. Grossly, the mass was located predominately in intestinal wall with grayish appearance and blurry boundary. Microscopically, almost all layers of the intestinal wall were infiltrated by pleomorphic tumor cells with diffuse and cohesive growth pattern. The neoplastic cells were mainly medium to large size with moderate basophilic cytoplasm. Most of them had hyperchromatic nuclei and prominent nucleoli. “Hallmark” cells were easily detected. Immunohistochemically, tumor cells are characterized by CD30, ALK, CD5, TIA-1, Granzyme B, EMA positive staining, and CD2, CD3, CD7, CD4, CD8, CD20, CD79a negative staining. The Epstein-Barr virus encoded RNAs (EBERs) genome was also negative. A diagnosis as primary small intestinal ALK positive anaplastic large cell lymphoma was finally made. The patient received CHOP chemotherapy and is alive till now without recurrence 5 months after enterectomy.

Conclusions

Primary small intestinal ALK positive anaplastic large cell lymphoma is rare. The accurate diagnosis should be based on combined consideration of clinical characteristics, CT image and pathological features, and should be distinguished from other lymphomas or solid tumors in small intestine.

Recent Advances in Aggressive Large B-cell Lymphomas: A Comprehensive Review

Diffuse large B-cell lymphoma (DLBCL) is an aggressive disease with considerable heterogeneity reflected in the 2008 World Health Organization classification. In recent years, genome-wide assessment of genetic and epigenetic alterations has shed light upon distinct molecular subsets linked to dysregulation of specific genes or pathways. Besides fostering our knowledge regarding the molecular complexity of DLBCL types, these studies have unraveled previously unappreciated genetic lesions, which may be exploited for prognostic and therapeutic purposes. Following the last World Health Organization classification, we have witnessed the emergence of new variants of specific DLBCL entities, such as CD30 DLBCL, human immunodeficiency virus-related and age-related variants of plasmablastic lymphoma, and EBV DLBCL arising in young patients. In this review, we will present an update on the clinical, pathologic, and molecular features of DLBCL incorporating recently gained information with respect to their pathobiology and prognosis. We will emphasize the distinctive features of newly described or emerging variants and highlight advances in our understanding of entities presenting a diagnostic challenge, such as T-cell/histiocyte-rich large B-cell lmphoma and unclassifiable large B-cell lymphomas. Furthermore, we will discuss recent advances in the genomic characterization of DLBCL, as they may relate to prognostication and tailored therapeutic intervention. The information presented in this review derives from English language publications appearing in PubMed throughout December 2015. For a complete outline of this paper, please visit: http://links.lww.com/PAP/A12.

An unusual case of anaplastic lymphoma kinase-positive large B-cell lymphoma in an elderly patient: A case report and discussion

We present an unusual case of anaplastic lymphoma kinase (ALK)-positive large B-cell lymphoma, with rapid clinical progression, which occurred in a 90-year-old male patient. The patient presented with numerous enlarged lymph nodes in the neck and mediastinum. Histopathological analysis of a single lymph node detected diffuse large immunoblastic- or plasmablastic-like tumor cells, which were strongly immunoreactive for ALK in a granular cytoplasmic distribution, but negative for the expression of CD20 and CD79a. In addition, polymerase chain reaction assays were unable to detect clonal rearrangements of the T cell receptor-γ and immunoglobulin heavy chain genes in the tumor lesion, and in situ hybridization tested negative for infection with Epstein-Barr virus. The patient underwent a single cycle of chemotherapy using the cyclophosphamide, doxorubicin, vincristine, prednisone, and etoposide (E-CHOP) regimen; however, the patient developed pleural effusions with respiratory distress, associated with clinical deterioration. The patient succumbed to the disease within 4 months of initial presentation. To the best of our knowledge, this is the eldest patient with this type of lymphoma to be reported in the literature.

Aggressive B-cell lymphomas: a review and practical approach for the practicing pathologist

Recent advances in diffuse large B-cell lymphoma are changing the way pathologists approach, diagnose, and report on this heterogeneous group of lymphomas. The purpose of this review is to provide a practical yet comprehensive approach to diffuse large B-cell lymphoma and aggressive B-cell lymphomas that can be used and easily interpreted by pathologists at all levels of training. It will address important concepts and current testing modalities which provide important prognostic information for the clinician when considering appropriate chemotherapeutic regimens for each patient's lymphoma diagnosis. It will also provide some insights into recently reported signaling pathways and molecular alterations and their contribution to lymphomagenesis and how identifying these abnormalities may provide future potential therapeutic targets for these aggressive lymphomas.

The biology and management of systemic anaplastic large cell lymphoma

Systemic anaplastic large cell lymphoma (ALCL) is an aggressive CD30(+) non-Hodgkin lymphoma. Anaplastic lymphoma kinase-positive (ALK+) ALCL is associated with the NPM-ALK t(2;5) translocation, which is highly correlated with the identification of the ALK protein by immunohistochemistry. ALK+ ALCL typically occurs in younger patients and has a more favorable prognosis with 5-year survival rates of 70% to 90% in comparison with 40% to 60% for ALK-negative (ALK-) ALCL. Studies support young age as a strong component of the favorable prognosis of ALK+ ALCL. Until recently, no recurrent translocations were identified in ALK- ALCL. However, emerging data now highlight that ALK- ALCL is genetically and clinically heterogeneous with a subset having either a DUSP22 translocation and a survival rate similar to ALK+ ALCL or a less common P63 translocation, the latter associated with an aggressive course. Anthracycline-based regimens such as cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) remain the standard first-line treatment choice for systemic ALCL, but in many patients with ALK- ALCL, it is ineffective, and thus it is often followed by consolidative autologous stem cell transplantation. However, selection of appropriate patients for intensified therapy remains challenging, particularly in light of genetic and clinical heterogeneity in addition to the emergence of new, effective therapies. The antibody drug conjugate brentuximab vedotin is associated with a high response rate (86%) and durable remissions in relapsed/refractory ALCL and is under investigation in the first-line setting. In the future, combining clinical and genetic biomarkers may aid in risk stratification and help guide initial patient management.

Activity of second-generation ALK inhibitors against crizotinib-resistant mutants in an NPM-ALK model compared to EML4-ALK

Anaplastic lymphoma kinase (ALK) is a tyrosine kinase receptor involved in both solid and hematological tumors. About 80% of ALK-positive anaplastic large-cell lymphoma (ALCL) cases are characterized by the t(2;5)(p23;q35) translocation, encoding for the aberrant fusion protein nucleophosmin (NPM)-ALK, whereas 5% of non-small-cell lung cancer (NSCLC) patients carry the inv(2)(p21;p23) rearrangement, encoding for the echinoderm microtubule-associated protein-like 4 (EML4)-ALK fusion. The ALK/c-MET/ROS inhibitor crizotinib successfully improved the treatment of ALK-driven diseases. However, several cases of resistance appeared in NSCLC patients, and ALK amino acid substitutions were identified as a leading cause of resistance to crizotinib. Second-generation ALK inhibitors have been developed in order to overcome crizotinib resistance. In this work, we profiled in vitro the activity of crizotinib, AP26113, ASP3026, alectinib, and ceritinib against six mutated forms of ALK associated with clinical resistance to crizotinib (C1156Y, L1196M, L1152R, G1202R, G1269A, and S1206Y) and provide a classification of mutants according to their level of sensitivity/resistance to the drugs. Since the biological activity of ALK mutations extends beyond the specific type of fusion, both NPM-ALK- and EML4-ALK-positive cellular models were used. Our data revealed that most mutants may be targeted by using different inhibitors. One relevant exception is represented by the G1202R substitution, which was highly resistant to all drugs (>10-fold increased IC₅₀ compared to wild type) and may represent the most challenging mutation to overcome. These results provide a prediction of cross-resistance of known crizotinib-resistant mutations against all second-generation tyrosine kinase inhibitors (TKIs) clinically available, and therefore could be a useful tool to help clinicians in the management of crizotinib-resistance cases.

The histological classification of diffuse large B-cell lymphomas

Diffuse large B-cell lymphomas (DLBCLs) are aggressive B-cell neoplasms with considerable clinical, biologic, and pathologic diversity, in part reflecting the functional diversity of the B-cell system and multiple pathways of transformation. In recent years, the advent of new high-throughput genomic technologies has provided new insights into the biology of DLBCL, leading to the identification of distinct molecular identities and novel pathogenetic pathways. This increasing complexity had led to an expanding number of entities in the World Health Organization classification. Using a multi-modality approach, the updated 2008 classification delineated some new subgroups, including DLBCLs associated with particular age groups or specific anatomic sites, as well as two borderline categories (tumors at the interface between classical Hodgkin lymphoma and DLBCL as well as between Burkitt lymphoma and DLBCL). This article reviews the histopathologic features of the various aggressive B-cell lymphoma subtypes included in the 2008 classification, with emphasis on some of the new entities as well as areas of diagnostic challenge.

Anaplastic large cell lymphomas: ALK positive, ALK negative, and primary cutaneous

Anaplastic large cell lymphomas (ALCLs) comprise a group of CD30-positive non-Hodgkin lymphomas that generally are of T-cell origin and share common morphologic and phenotypic characteristics. The World Health Organization recognizes 3 entities: primary cutaneous ALCL (pcALCL), anaplastic lymphoma kinase (ALK)-positive ALCL, and, provisionally, ALK-negative ALCL. Despite overlapping pathologic features, these tumors differ in clinical behavior and genetics. pcALCL presents in the skin and, while it may involve locoregional lymph nodes, rarely disseminates. Outcomes typically are excellent. ALK-positive ALCL and ALK-negative ALCL are systemic diseases. ALK-positive ALCLs consistently have chromosomal rearrangements involving the ALK gene with varied gene partners, and generally have a favorable prognosis. ALK-negative ALCLs lack ALK rearrangements and their genetic and clinical features are more variable. A subset of ALK-negative ALCLs has rearrangements in or near the DUSP22 gene and has a favorable prognosis similar to that of ALK-positive ALCL. DUSP22 rearrangements also are seen in a subset of pcALCLs. In this review, we discuss the clinical, morphologic, phenotypic, genetic, and biological features of ALCLs.