Array-CGH analysis of cutaneous anaplastic large cell lymphoma

Updates in pathobiological aspects of anaplastic large cell lymphoma

Anaplastic large cell lymphomas (ALCL) encompass several distinct subtypes of mature T-cell neoplasms that are unified by the expression of CD30 and anaplastic cytomorphology. Identification of the cytogenetic abnormality t(2;5)(p23;q35) led to the subclassification of ALCLs into ALK+ ALCL and ALK- ALCL. According to the most recent World Health Organization (WHO) Classification of Haematolymphoid Tumours as well as the International Consensus Classification (ICC) of Mature Lymphoid Neoplasms, ALCLs encompass ALK+ ALCL, ALK- ALCL, and breast implant-associated ALCL (BI-ALCL). Approximately 80% of systemic ALCLs harbor rearrangement of ALK, with NPM1 being the most common partner gene, although many other fusion partner genes have been identified to date. ALK- ALCLs represent a heterogeneous group of lymphomas with distinct clinical, immunophenotypic, and genetic features. A subset harbor recurrent rearrangement of genes, including TYK2, DUSP22, and TP63, with a proportion for which genetic aberrations have yet to be characterized. Although primary cutaneous ALCL (pc-ALCL) is currently classified as a subtype of primary cutaneous T-cell lymphoma, due to the large anaplastic and pleomorphic morphology together with CD30 expression in the malignant cells, this review also discusses the pathobiological features of this disease entity. Genomic and proteomic studies have contributed significant knowledge elucidating novel signaling pathways that are implicated in ALCL pathogenesis and represent candidate targets of therapeutic interventions. This review aims to offer perspectives on recent insights regarding the pathobiological and genetic features of ALCL.

Anaplastic Large Cell Lymphoma: Molecular Pathogenesis and Treatment

Simple Summary

Anaplastic large cell lymphoma is a rare type of disease that occurs throughout the world and has four subtypes. A summary and comparison of these subtypes can assist with advancing our knowledge of the mechanism and treatment of ALCL, which is helpful in making progress in this field.

Abstract

Anaplastic large cell lymphoma (ALCL) is an uncommon type of non-Hodgkin’s lymphoma (NHL), as well as one of the subtypes of T cell lymphoma, accounting for 1 to 3% of non-Hodgkin’s lymphomas and around 15% of T cell lymphomas. In 2016, the World Health Organization (WHO) classified anaplastic large cell lymphoma into four categories: ALK-positive ALCL (ALK+ALCL), ALK-negative ALCL (ALK−ALCL), primary cutaneous ALCL (pcALCL), and breast-implant-associated ALCL (BIA-ALCL), respectively. Clinical symptoms, gene changes, prognoses, and therapy differ among the four types. Large lymphoid cells with copious cytoplasm and pleomorphic characteristics with horseshoe-shaped or reniform nuclei, for example, are found in both ALK+ and ALK−ALCL. However, their epidemiology and pathogenetic origins are distinct. BIA-ALCL is currently recognized as a new provisional entity, which is a noninvasive disease with favorable results. In this review, we focus on molecular pathogenesis and management of anaplastic large cell lymphoma.

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.

CD30-positive primary cutaneous lymphoproliferative disorders: molecular alterations and targeted therapies

Primary cutaneous CD30-positive T-cell lymphoproliferative disorders are the second most common subgroup of cutaneous T-cell lymphomas. They include two clinically different entities with some overlapping features and borderline cases: lymphomatoid papulosis and primary cutaneous anaplastic large cell lymphoma. Molecular studies of primary cutaneous anaplastic large cell lymphoma reveal an increasing level of heterogeneity that is associated with histological and immunophenotypic features of the cases and their response to specific therapies. Here, we review the most significant genetic, epigenetic and molecular alterations described to date in primary cutaneous CD30-positive T-cell lymphoproliferative disorders, and their potential as therapeutic targets.

Copy number variation in archival melanoma biopsies versus benign melanocytic lesions

BACKGROUND

Skin melanocytes can give rise to benign and malignant neoplasms. Discrimination of an early melanoma from an unusual/atypical benign nevus can represent a significant challenge. However, previous studies have shown that in contrast to benign nevi, melanoma demonstrates pervasive chromosomal aberrations.

OBJECTIVE

This substantial difference between melanoma and benign nevi can be exploited to discriminate between melanoma and benign nevi.

METHODS

Array-comparative genomic hybridization (aCGH) is an approach that can be used on DNA extracted from formalin-fixed paraffin-embedded (FFPE) tissues to assess the entire genome for the presence of changes in DNA copy number. In this study, high resolution, genome-wide single-nucleotide polymorphism (SNP) arrays were utilized to perform comprehensive and detailed analyses of recurrent copy number aberrations in 41 melanoma samples in comparison with 21 benign nevi.

RESULTS

We found statistically significant copy number gains and losses within melanoma samples. Some of the identified aberrations are previously implicated in melanoma. Moreover, novel regions of copy number alterations were identified, revealing new candidate genes potentially involved in melanoma pathogenesis.

CONCLUSIONS

Taken together, these findings can help improve melanoma diagnosis and introduce novel melanoma therapeutic targets.

Pathology of T-cell lymphomas: diagnosis and biomarker discovery

T-cell lymphomas are a group of predominantly rare hematologic malignancies that tend to recapitulate different stages of T-cell development, in a similar way that B-cell lymphomas do. As opposed to B-cell lymphomas, the understanding of the biology and the classification of T-cell lymphomas are somewhat rudimentary, and numerous entities are still included as 'provisional categories' in the World Health Classification of hematolopoietic malignancies. A relevant and useful classification of these disorders have been difficult to accomplish because of the rarity nature of them, the relative lack of understanding of the molecular pathogenesis, and their morphological and immunophenotypical complexity. Overall, T-cell lymphomas represent only 15 % of all non-Hodgkin lymphomas. This review is focused on addressing the current status of the categories of mature T-cell leukemias and lymphomas (nodal and extranodal) using an approach that incorporates histopathology, immunophenotype, and molecular understanding of the nature of these disorders, using the same philosophy of the most recent revised WHO classification of hematopoietic malignancies.