ALK-positive (2p23 rearranged) anaplastic large cell lymphoma with localization to the skin in a pediatric patient

Primary cutaneous, epidermotropic mycosis fungoides-like presentation: critical appraisal and description of two novel cases, broadening the spectrum of ALK+ T-cell lymphoma

Leading from a two-case series, including two patients receiving a diagnosis of epidermotropic T-cell lymphoma, featuring a mycosis fungoides (MF)-like clinical pattern and ALK expression and molecular alteration, we performed a critical appraisal of ALK+ primary cutaneous T-cell lymphomas (pcTCL). Considering our patients and the literature, 32 cases were retrieved, 7 of which featured an MF-like clinical picture over a 4-to-20-year period. MF-like cases show distinctive histology, comprising a predominantly epidermotropic infiltration of small-to-large, atypical-to-pleomorphic, with few anaplastic cells, negligible-to-intense CD30-expression, and a CD4+/cytotoxic granule+ phenotype. These features should prompt a search for ALK expression captured by the ALK D5F3 clone. Bona fide ALK+ pcTCL is very rare, and existent data suggest the presence of a broader pattern of disease, including instances mimicking MF and/or primary cutaneous CD8+ aggressive epidermotropic cytotoxic T-cell lymphoma. The major challenges in dealing with this subset include prodromal phases, misinterpreted as inflammatory dermatosis or parapsoriasis/early phase MF both clinically and histologically, while recognition of its ALK-driven biology is hampered both by the unusual clinic-pathologic pattern of the disease, which stands apart from the classical (i.e., nodal) picture of ALK+ anaplastic large cell lymphoma and by the low sensitivity of ALK1 clone. Data on its optimal management are far from being conclusive: An MF-like approach is currently chosen, but depending on CD30 and, most notably, ALK expression, a targeted therapy could be envisaged in advanced stages, as clinical response to ALK inhibition was documented in one patient.

Challenges in utilizing ALK expression to distinguish primary cutaneous from systemic anaplastic large cell lymphoma

Anaplastic large cell lymphoma (ALCL) is a CD30+ peripheral T-cell lymphoma with a clinical spectrum including cutaneous and systemic presentations. While primary cutaneous ALCL (pcALCL) has a favorable prognosis, systemic ALCL (sALCL) has poorer survival outcomes. Expression of anaplastic lymphoma kinase (ALK) by malignant cells has been suggested to distinguish sALCL from pcALCL. However, there have been documented cases of ALK-positive ALCL confined to the skin. The present study reviewed characteristics of published cutaneous ALK-positive ALCL cases to distinguish between these two entities. In 23 identified adults with ALK-positive pcALCL, 26% developed systemic involvement and 74% had skin-limited disease. In 14 pediatric patients, 36% had both cutaneous and systemic involvement and 64% had cutaneous disease only. This analysis revealed that pcALCL and sALCL could not reliably be distinguished by ALK expression or nuclear vs. cytoplasmic localization. Localized treatment with frequent monitoring may be sufficient in ALK-positive pcALCL until there is evidence of progression. Physicians should be aware of the overall spectrum of ALCL, including cutaneous limited disease, systemic disease, disease with NPM-ALK translocation, disease with ALK positivity and disease with skin recurrence.

Paediatric cutaneous lymphomas including rare subtypes: A 40-year experience at a tertiary referral centre

BACKGROUND

Primary cutaneous lymphomas are neoplasms of the immune system with a distinct tropism for the skin and an absence of extracutaneous manifestations at the time of diagnosis. Studies focusing on cutaneous lymphomas in children and adolescents remain scarce and often do not encompass the rare subtypes.

OBJECTIVES

To address this knowledge gap by describing the clinical, histological and molecular characteristics of a large group of paediatric patients affected by primary cutaneous lymphoma. We also provided the Paediatric Primary Cutaneous Lymphoma Atlas that illustrates the clinicopathological spectrum of observed presentations, in the hope of supporting other physicians in the diagnostic process.

METHODS

Retrospective chart review of paediatric patients diagnosed with primary cutaneous lymphomas between 1980 and 2022 at the Paediatric Dermatology Unit of Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan.

RESULTS

A total of 101 patients (58 males, 43 females) met the inclusion criteria. The most common subtypes were lymphomatoid papulosis (n = 48) and mycosis fungoides (n = 31). These were followed by primary cutaneous CD4+ small/medium T-cell lymphoproliferative disorders (n = 7), primary cutaneous anaplastic large-cell lymphomas (n = 5), primary cutaneous marginal zone B-cell lymphomas (n = 3), primary cutaneous follicle centre lymphomas (n = 2), subcutaneous panniculitis-like T-cell lymphomas (n = 2), primary cutaneous peripheral T-cell lymphoma not otherwise specified (n = 1), primary cutaneous precursor B-lymphoblastic lymphoma (n = 1) and Sézary syndrome (n = 1). Clinical follow-up data covering a median of 70.8 months (range 1-324) were available for 74 patients, of whom three died due to cutaneous lymphoma.

CONCLUSIONS

Our findings shed light on the peculiar aspects and long-term outcomes of paediatric cutaneous lymphomas, particularly emphasizing their distinctive features in comparison to their adult counterparts and exploring the less common subtypes. Further larger-scale studies are warranted to better characterize these entities and to achieve a more rapid and accurate diagnosis.

Primary Cutaneous CD30-Positive Lymphoproliferative Disorders-Current Therapeutic Approaches with a Focus on Brentuximab Vedotin

One of the most common subgroups of cutaneous T-cell lymphomas is that of primary cutaneous CD30-positive lymphoproliferative disorders. The group includes lymphomatoid papulosis (LyP) and primary cutaneous anaplastic large cell lymphoma (pcALCL), as well as some borderline cases. Recently, significant progress has been made in understanding the genetics and treatment of these disorders. This review article summarises the clinical evidence supporting the current treatment options for these diseases. Recent years have seen the introduction of novel agents into clinical practice; most of these target CD30, such as anti-CD30 monoclonal antibodies and conjugated antibodies (brentuximab vedotin), bispecific antibodies and cellular therapies, particularly anti-CD30 CAR-T cells. This paper briefly reviews the biology of CD30 that makes it a good therapeutic target and describes the anti-CD30 therapies that have emerged to date.

Primary cutaneous T-cell lymphoma: a review of the most common entities with focus on recent updates

Cutaneous T-cell lymphomas are an heterogeneous group of uncommon lymphoid neoplasms that are challenging to diagnose and require close collaboration between dermatologists, pathologists and hematologists/oncologists. This article reviews the most common cutaneous T-cell lymphomas: mycosis fungoides (both classic and variant forms) as well as its leukemic counterpart Sézary syndrome, CD30+ T-cell lymphoproliferative disorders including the ever-expanding group of lymphomatoid papulosis and primary cutaneous anaplastic large cell lymphoma, and primary cutaneous CD4+ small/medium lymphoproliferative disorder. We discuss the classic clinical and histopathologic features of these lymphomas and review how they can be distinguished from reactive entities. In particularly, updates to these diagnostic categories and current controversies in classification are highlighted. Moreover, we review the prognosis and treatment for each entity. These lymphomas exhibit variable prognosis, and therefore it is important to correctly classify atypical cutaneous T-cell infiltrates for appropriate patient treatment and prognosis. Cutaneous T-cell lymphomas are at the interface of several medical specialties; this review seeks to summarize key features of these lymphomas and highlight new and emerging insights into these lymphomas.

Primary Cutaneous Anaplastic Large Cell Lymphoma-A Review of Clinical, Morphological, Immunohistochemical, and Molecular Features

Primary cutaneous anaplastic large cell lymphoma (ALCL) is the second most common cutaneous T-cell lymphoma after mycosis fungoides and belongs to the spectrum of cutaneous CD30+ T-cell lymphoproliferative disorders. Although primary cutaneous ALCL usually presents as a localized nodule or papule with or without ulceration, multifocal lesions may occur in up to 20% of cases. Histologically, primary cutaneous ALCL consists of a diffuse dermal infiltrate of medium to large anaplastic/pleomorphic cells with abundant amphophilic-to-eosinophilic cytoplasm, horseshoe-shaped nuclei, strong and diffuse expression of CD30, and with focal or no epidermotropism. The neoplastic infiltrate may show angiocentric distribution and may extend to the subcutis. Patients with localized or multifocal disease have a similar prognosis with a 10-year overall survival rate of 90%. Approximately 30% of primary cutaneous ALCLs harbor a DUSP22 (6p25.3) gene rearrangement that results in decreased expression of this dual-specific phosphatase, decreased STAT3 activation, and decreased activity of immune and autoimmune-mediated mechanisms regulated by T-cells.

Primary cutaneous T-cell lymphoma: a review of the most common entities with focus on recent updates

Cutaneous T-cell lymphomas are an heterogeneous group of uncommon lymphoid neoplasms that are challenging to diagnose and require close collaboration between dermatologists, pathologists and hematologists/oncologists. This article reviews the most common cutaneous T-cell lymphomas: mycosis fungoides (both classic and variant forms) as well as its leukemic counterpart Sézary syndrome, CD30+ T-cell lymphoproliferative disorders including the ever-expanding group of lymphomatoid papulosis and primary cutaneous anaplastic large cell lymphoma, and primary cutaneous CD4+ small/medium lymphoproliferative disorder. We discuss the classic clinical and histopathologic features of these lymphomas and review how they can be distinguished from reactive entities. In particularly, updates to these diagnostic categories and current controversies in classification are highlighted. Moreover, we review the prognosis and treatment for each entity. These lymphomas exhibit variable prognosis, and therefore it is important to correctly classify atypical cutaneous T-cell infiltrates for appropriate patient treatment and prognosis. Cutaneous T-cell lymphomas are at the interface of several medical specialties; this review seeks to summarize key features of these lymphomas and highlight new and emerging insights into these lymphomas.

Recent advances in cutaneous lymphoma-implications for current and future classifications

The Revised European-American Classification of mature lymphoid neoplasms published in 1994 and the 2001, 2008 and 2016 WHO classifications that followed, were the product of international collaboration and consensus amongst haematopathologists, geneticists, molecular scientists and clinicians. Primary cutaneous lymphomas were fully incorporated into this process following the publication of the WHO-EORTC classification of cutaneous lymphomas in 2005. The definition, diagnostic criteria and recommended studies for primary cutaneous lymphoma continue to be refined. The 2022 International Consensus Classification represents the most recent update and an overview of all the main entities presenting primarily in the skin, together with the major changes in classification, are summarized herein. Primary cutaneous marginal zone lymphoma is segregated from other extranodal marginal zone lymphomas of mucosa-associated lymphoid tissue (MALT lymphoma) and downgraded to a lymphoproliferative disorder in line with its markedly indolent behaviour. In addition, two subtypes are recognised, based largely but not exclusively on whether they are heavy chain class-switched or IgM positive. Similarly, in keeping with a trend to greater conservatism, primary cutaneous acral CD8 positive T cell lymphoma is now also classified as a lymphoproliferative disorder. In addition, significant new insights into the biology of primary cutaneous lymphoma have also recently been forthcoming and will be presented. These studies have enhanced our knowledge of genetic, epigenetic and transcriptional changes in this group of diseases. They not only identify potential targets for novel therapies, but also raise as yet unanswered questions as to how we categorise cutaneous lymphomas, particularly with respect to relationships with similar lymphomas at extracutaneous sites.

Etiopathogenesis, Diagnosis, and Treatment Strategies for Lymphomatoid Papulosis with Particular Emphasis on the Role of the Immune System

Lymphomatoid papulosis (LyP) is a very rare disease that belongs to the group of CD30+ lymphoproliferative skin diseases. LyP is localized or generalized and usually presents as isolated or clustered red/brown-red lesions in the form of nodules and/or papules. The course of the disease is in most cases mild; however, depending on concomitant risk factors and history, it may progress to lymphoma, significantly reducing the survival rate and prognosis. Importantly, the clinical picture of the disease remains somewhat ambiguous, leading to a large number of misdiagnoses that result in inappropriate treatment, which is usually insufficient to alleviate symptoms. In addition to clinical manifestations, the histological characteristics vary widely and usually overlap with other conditions, especially those belonging to the group of lymphoproliferative disorders. Although diagnosis remains a challenge, several recommendations and guidelines have been introduced to standardize and facilitate the diagnostic process. This article reviews the available literature on the most important aspects of etiopathogenesis, clinical and histopathological features, diagnostic criteria, and possible treatment strategies for LyP, with particular emphasis on the role of the immune system.

Genetic alterations and oxidative stress in T cell lymphomas

T cell lymphomas encompass a diverse group of Non-Hodgkin lymphomas with a wide spectrum of clinical, immunological and pathological manifestations. In the last two decades there has been a progress in our understanding of the cell of origin, genetic abnormalities and their impact on behaviour in T cell lymphomas. Genetic alterations are one of the critical drivers of the pathogenesis of T cell lymphoma. Disease progression has been correlated with multiple genetic abnormalities where malignant clones arise primarily out of the host immune surveillance arsenal. There are many cellular processes involved in disease development, and some of them are T cell signaling, differentiation, epigenetic modifications, and immune regulation. Modulation of these crucial pathways via genetic mutations and chromosomal abnormalities possessing either point or copy number mutations helps tumor cells to develop a niche favourable for their growth via metabolic alterations. Several metabolic pathways especially regulation of redox homeostasis is critical in pathogenesis of lymphoma. Disruption of redox potential and induction of oxidative stress renders malignant cells vulnerable to mitochondrial damage and triggers apoptotic pathways causing cell death. Targeting genetic abnormalities and oxidative stress along with current treatment regime have the potential for improved therapeutics and presents new combination approaches towards selective treatment of T cell lymphomas.

Primary Lymphomas of the Breast: A Review

Lymphomas of the breast are rare neoplasms that arise from breast lymphoid tissue and are characterised by neoplastic B or T cells. Breast lymphomas arising from B cells include, but are not limited to, diffuse large B cell lymphoma, follicular lymphoma, extra-nodal marginal zone lymphoma and Burkitt lymphoma. Anaplastic large cell lymphoma (ALCL) is of a T cell origin and both anaplastic lymphoma kinase (ALK)-positive and ALK-negative presentations have been noted in the breast. In addition, there is a more recently identified presentation of ALK-negative ALCL that arises around textured breast implants and is usually confined to a periprosthetic fibrous capsule. Here, we discuss the clinical presentations, histological and immunohistochemical features and treatment options for each type of primary breast lymphoma. We hope that this review will highlight the importance of the timely and accurate diagnosis of breast lymphoma in order to tailor the most appropriate treatment. We also wish to raise awareness of the breast implant-associated lymphomas, with the goal of stimulating work that will aid our understanding of their epidemiology and pathogenesis.

Genetic and epigenetic insights into cutaneous T-cell lymphoma

Primary cutaneous T-cell lymphomas (CTCL) constitute a heterogeneous group of non-Hodgkin T-cell lymphomas that present in the skin. In recent years significant progress has been made in the understanding of the pathogenesis of CTCL. Progress in CTCL classifications combined with technical advances, in particular next generation sequencing (NGS), enabled a more detailed analysis of the genetic and epigenetic landscape and transcriptional changes in clearly defined diagnostic entities. These studies not only demonstrated extensive heterogeneity between different CTCL subtypes but also identified recurrent alterations that are highly characteristic for diagnostic subgroups of CTCL. The identified alterations in particular involve epigenetic remodelling, cell cycle regulation, and the constitutive activation of targetable, oncogenic pathways. In this respect, aberrant JAK-STAT signaling is a recurrent theme, however not universal for all CTCL and with seemingly different underlaying causes in different entities. A number of the mutated genes identified are potentially actionable targets for the development of novel therapeutic strategies. Moreover, these studies have produced an enormous amount of information that will be critically important for the further development of improved diagnostic and prognostic biomarkers that can assist in the clinical management of CTCL patients. In the present review the main findings of these studies in relation to their functional impact on the malignant transformation process are discussed for different subtypes of CTCL.

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.

Primary cutaneous T-cell lymphomas in childhood and adolescence

Primary cutaneous lymphomas are extranodal non-Hodgkin lymphomas of T- or B- cell origin, that predominantly affect older patients but have been reported in all age groups and as early as in the first years of life. Diagnosis of cutaneous lymphomas is challenging and requires high clinical suspicion and close collaboration between dermatologists, pediatric oncologists and pathologists. Skin involvement of non-Hodgkin lymphomas in children or adolescents can either be primary cutaneous or secondary due to an underlying nodal lymphoma. The most common primary cutaneous lymphomas encountered in children are of T-cell origin, with mycosis fungoides being the most prevalent cutaneous T-cell lymphoma, followed by CD30⁺ lymphoproliferative disorders. While cutaneous lymphomas share clinicopathologic characteristics between juvenile and adult forms, there are important differences in terms of clinical presentation, diagnosis and treatment. The hypopigmented variant of mycosis fungoides seems to be overrepresented in the pediatric age group. Prognosis and treatment of mycosis fungoides are stage dependent. The majority of children present with early-stage disease and respond well to topical corticosteroids and phototherapy.

Primär kutane T‐Zell‐Lymphome im Kindes‐ und Jugendalter

Primär kutane Lymphome sind extranodale T- oder B-Zell-Non-Hodgkin-Lymphome, die vorwiegend ältere Patienten betreffen, aber in allen Altersgruppen einschließlich der ersten Lebensjahre auftreten können. Die Diagnose kutaner Lymphome ist eine Herausforderung und erfordert einen hohen klinischen Verdacht sowie enge Zusammenarbeit zwischen Dermatologen, pädiatrischen Onkologen und Pathologen. Generell müssen primär kutane Lymphome von sekundär kutanen Lymphomen, welche meist von nodalen oder extranodalen Lymphomen ausgehen, unterschieden werden. Die häufigsten primär kutanen Lymphome im Kindesalter sind T-Zell Lymphome, wobei Mycosis fungoides das häufigste kutane T-Zell-Lymphom darstellt, gefolgt von CD30+ lymphoproliferativen Erkrankungen. Während klinisch-pathologische Merkmale kutaner Lymphome bei Jugendlichen und Erwachsenen ähnlich sind, gibt es wichtige Unterschiede bezüglich klinischer Präsentation, Diagnose und Behandlung. Die hypopigmentierte Variante der Mycosis fungoides scheint in der pädiatrischen Altersgruppe überrepräsentiert zu sein. Prognose und Behandlung der Mycosis fungoides sind stadienabhängig. Die Mehrheit der Kinder weist ein frühes Krankheitsstadium auf und spricht gut auf topische Kortikosteroide und Phototherapie an.

How I Diagnose Anaplastic Large Cell Lymphoma

OBJECTIVES

This review describes our approach to the diagnosis of all 4 anaplastic large cell lymphoma (ALCL) entities.

METHODS

ALCLs are a group of CD30-positive mature T-cell lymphomas with similar morphologic and phenotypic characteristics but variable clinical and genetic features. They include systemic ALK-positive ALCL, systemic ALK-negative ALCL, primary cutaneous ALCL, and the recently described provisional entity breast implant-associated ALCL.

RESULTS

In cases with classic features, the diagnosis of ALCL is often straightforward. However, variant histology, the importance of clinical history, and multiple antigenic aberrancies all present challenges to accurate diagnosis and subclassification.

CONCLUSIONS

A systematic approach to the diagnosis of ALCL and awareness of potential mimics are critical to avoid misdiagnosis. It is also crucial to correctly identify localized forms of ALCL to avoid classification as systemic ALCL and subsequent overtreatment.

A Systematic Approach to the Cutaneous Lymphoid Infiltrates: A Clinical, Morphologic, and Immunophenotypic Evaluation

CONTEXT.—

The evaluation of cutaneous lymphoid infiltrates, both neoplastic and inflammatory, occurs very frequently in routine dermatopathologic examination and consultation practices. The "tough" cutaneous lymphoid infiltrate is feared by many pathologists; skin biopsies are relatively small, whereas diagnostic possibilities are relatively broad. It is true that cutaneous lymphomas can be difficult to diagnose and that in many circumstances multiple biopsies are required to establish a correct diagnostic interpretation. As a reminder, one should understand that low-grade cutaneous lymphomas are indolent disorders that usually linger for decades and that therapy does not result in disease cure. It is also important to remember that in most circumstances, those patients will die from another process that is completely unrelated to a diagnosis of skin lymphoma (even in the absence of specific therapy).

OBJECTIVE.—

To use a clinicopathologic, immunophenotypic, and molecular approach in the evaluation of common lymphocytic infiltrates.

DATA SOURCES.—

An in-depth analysis of updated literature in the field of cutaneous lymphomas was done, with particular emphasis on updated terminology from the most recent World Health Organization classification of skin and hematologic tumors.

CONCLUSIONS.—

A diagnosis of cutaneous lymphoid infiltrates can be adequately approached using a systematic scheme following the proposed ABCDE system. Overall, cutaneous T- and B-cell lymphomas are rare and "reactive" infiltrates are more common. Evaluation of lymphoid proliferations should start with a good sense of knowledge of the clinical presentation of the lesions, the clinical differential considerations, and a conscientious and appropriate use of immunohistochemistry and molecular tools.

Recurrent Oncogenic JAK and STAT Alterations in Cutaneous CD30-Positive Lymphoproliferative Disorders

The group of cutaneous CD30-positive lymphoproliferative disorders (LPD) comprises two different entities, namely lymphomatoid papulosis (LyP) and cutaneous anaplastic large T-cell lymphoma (cALCL). LyP constitutes a benign lymphoproliferation with spontaneously regressing papules, whereas cALCL presents with solitary or multiple skin tumors with a low propensity to disseminate. To elucidate the hitherto largely unknown molecular pathogenesis of these entities, we performed comprehensive next-generation sequencing in a well-characterized cohort of 12 patients. Considering the low tumor cell content of LyP, we applied targeted sequencing technologies with a hybrid capture-based DNA library preparation approach and for the identification of fusion transcripts an anchored multiplex PCR enrichment kit. As the major finding, we detected, in 50% of LPD, genetic events that implied a constitutively activated Janus kinase-signal transducer and activator of transcription signaling (JAK-STAT) pathway in these entities. The identified molecular aberrations comprised either pathogenic STAT mutations or oncogenic fusion transcripts comprising effector domains of JAK. With respect to LyP, we report to our knowledge such previously unreported genetic aberrations in this specific entity. The detection of these convergent aberrations within the JAK-STAT signaling pathway deciphers common potential driving mechanisms of lymphomagenesis within LPD being shared between LyP and cALCL. Moreover, the presence of these oncogenic alterations paves the way to develop novel personalized treatment strategies.

Primary Pediatric Cutaneous T-Cell Lymphoproliferative Disorders: 3 New Cases

Primary cutaneous lymphoproliferative disorders are a composite group of diseases with considerable differences in histopathologic, immunophenotypic, and clinical features. They are exceedingly rare in children and in the literature only few cases are reported with extremely different therapeutic approaches. Because of the rarity of cutaneous lymphomas we consider crucial to increase the knowledge of these diseases providing every single case. We present 3 pediatric cases of primary cutaneous T-cell lymphomas occurred to our center with different features and therapeutic approach.

Cutaneous T-cell Lymphoma

Cutaneous T-cell lymphomas comprise a heterogeneous group of diseases characterized by monoclonal proliferations of T lymphocytes primarily involving skin, modified skin appendages, and some mucosal sites. This article addresses the basic clinical, histologic, and immunohistochemical characteristics of this group of diseases, with additional attention to evolving literature on dermoscopy, reflectance confocal microscopy, flow cytometry, and molecular data that may increasingly be applied to diagnostic and therapeutic algorithms in these diseases. Select unusual phenotypes or diagnostic examples of classic phenotypes are demonstrated, and flags for consideration while making a pathologic diagnosis of cutaneous T-cell lymphoma are suggested.

ALK-positive primary cutaneous anaplastic large cell lymphoma: a case report and review of the literature

Anaplastic large cell lymphoma (ALCL) limited to the skin is a distinct disease that is designated primary cutaneous ALCL (pcALCL). It has an indolent course with a significantly better prognosis compared to systemic ALCL (sALCL). Anaplastic lymphoma kinase (ALK) expression in lesions of cutaneous ALCL is classically considered to be a marker for skin involvement by sALCL. However, recent reports of patients with ALK-positive pcALCL challenge this concept and raise prognostic and therapeutic dilemmas. Herein, we report a case of ALK-positive pcALCL in a 45-year-old woman who was treated with local radiotherapy. We review previously reported cases in the literature to better characterize this rare variant. Overall, the rates of cutaneous recurrence, systemic dissemination, and disease-related mortality in ALK-positive pcALCL do not differ from those previously reported in pcALCL. ALK-positive pcALCL is diagnosed at younger age and has a better disease course in children compared to adults with lower incidences of skin recurrence and progression to systemic disease. We conclude that ALK-positivity in cutaneous ALCL does not necessarily imply systemic disease. ALK-positive pcALCL has an excellent prognosis and should be treated by excision and/or radiotherapy. However, patients must remain under close long-term follow-up as recurrence and progression to systemic disease may occur.

Anaplastic Lymphoma Kinase in Cutaneous Malignancies

Anaplastic lymphoma kinase (ALK) is a receptor tyrosine kinase that has been implicated in the pathogenesis of a variety of neoplasms. As suggested by its name, ALK was first described as part of a translocation product in cases of anaplastic large-cell lymphoma, with other genetic and cytogenetic ALK mutations subsequently coming to attention in the development of many other hematologic and solid organ malignancies. ALK has now been shown to play a role in the pathogenesis of several cutaneous malignancies, including secondary cutaneous systemic anaplastic large-cell lymphoma (ALCL) and primary cutaneous ALCL, melanoma, spitzoid tumors, epithelioid fibrous histiocytoma, Merkel cell carcinoma, and basal cell carcinoma. The characterization of ALK-positivity in these cutaneous malignancies presents exciting opportunities for utilizing ALK-targeted inhibitors in the treatment of these diseases.

Primary cutaneous anaplastic large cell lymphoma

Primary cutaneous anaplastic large cell lymphoma (PC-ALCL) is a CD30+ lymphoproliferative disorder (LPD) of the skin with a relatively good prognosis in the absence of high-stage disease. CD30+ LPDs comprise approximately 25%-30% of primary cutaneous lymphomas and as a group represent the second most common clonal T-cell neoplasm of the skin behind mycosis fungoides. Diagnosis of PC-ALCL relies strongly on clinicopathologic correlation given the potential morphologic, clinical and molecular overlap with the other cutaneous CD30+ LPD, lymphomatoid papulosis, and more aggressive hematolymphoid neoplasms.

Pediatric case of anaplastic lymphoma kinase-positive anaplastic large cell lymphoma forming a solitary skin tumor on the forearm

A 5-year-old girl noticed a rapidly growing reddish nodule on her right forearm. Although oral antibiotics had been administrated for 2 weeks, the tumor enlarged. Skin biopsy revealed excessive infiltration of atypical neoplastic cells expressing CD4, CD30 and anaplastic lymphoma kinase (ALK). These histological and immunohistochemical findings were consistent with anaplastic large cell lymphoma (ALCL). Computed tomography showed multiple lymphadenopathy, but lymph node biopsy and bone marrow examination did not show any evidence of systemic dissemination. However, due to the positive results for ALK and multiple lymphadenopathy, we diagnosed ALK-positive ALCL forming a solitary skin tumor on the forearm. The patient received chemotherapy and presented marked improvement. This paper discusses the difficulty of diagnosing pediatric ALK-positive ALCL limited to the skin and reviews the medical published work.

Genetics of anaplastic large cell lymphoma

Anaplastic large cell lymphoma (ALCL) comprises a group of T-cell non-Hodgkin lymphomas unified by common morphologic and immunophenotypic characteristics, but with a spectrum of clinical presentations and behaviors. Early identification of anaplastic lymphoma kinase (ALK) gene rearrangements in some ALCLs led to recognition of ALK as an important diagnostic and prognostic biomarker, and a key driver of ALCL pathobiology. Rearrangements and other genetic abnormalities of ALK subsequently were identified in diverse other human malignancies. Recent clinical, pathologic, and genetic data have begun to shed light on ALK-negative ALCLs, revealing significant heterogeneity within this more ill-defined entity.