Primary Cutaneous CD8+ Small- to Medium-Sized Lymphoproliferative Disorder in Extrafacial Sites: Clinicopathologic Features and Concept on Their Classification

Homozygous Loss of CDKN2 in Primary Cutaneous CD8(+) Lymphoma NOS

ABSTRACT

Primary cutaneous acral CD8(+) lymphoma (AL) has been accepted as primary cutaneous acral CD8-positive T-cell lymphoproliferative disorder in the revised WHO and updated WHO-EORTC lymphoma classifications. Commonly arising on the ears and comprising a clonal cytotoxic CD8 + T-cell infiltrate, almost all cases follow an indolent clinical course. A single aggressive case reported in the literature had a deletion at the CDKN2 locus at 9p21. We report an atypical CD8 + T-cell proliferation arising on the chest of an elderly man who had some similarities to AL but with a very high proliferation rate, absent p16 protein expression, and homozygous loss of the CDKN2 locus using FISH analysis. A diagnosis of peripheral T-cell lymphoma not otherwise specified (PTCL NOS) was preferred. Analyses of 4 cases of AL demonstrated often low p16 protein expression but intact CDKN2 loci. This case raises the problems of the boundaries between AL and PTCL NOS, and a possible role in the loss of p16 function in pathogenesis.

Primary cutaneous acral CD8-positive T-cell lymphoproliferative disorder: A clinical and histologic retrospective cohort study

Clonally restricted, non-epidermotropic, low-grade, CD8-positive T-cell infiltrates of the skin was recognized as a unique form of indolent CD8-positive lymphoproliferative disease in 2007 when it was first called primary cutaneous indolent CD8-positive lymphoid proliferation. More recently, the designation of primary cutaneous acral CD8-positive T-cell lymphoproliferative disorder has been used. It is unique as a cutaneous lymphoproliferative disorder because of relative uniformity in its clinical presentation and histomorphology. It has been recognized as having an interesting predilection for the ear and acral sites, characteristically presenting as a solitary lesion. The basic morphology is one characterized by a non-epidermotropic, tumefactive infiltrate of well-differentiated, noncerebriform, atypical, small- to intermediate-sized lymphocytes that exhibit a specific phenotype characterized by CD8 and TIA positivity in concert with a distinct perinuclear Golgi staining pattern for CD68. The typical presentation is in the context of a solitary lesion, which can be treated surgically or with local irradiation. We describe in detail two very unusual cases that expand the clinical spectrum of this condition given the non-acral localization, the multiplicity of lesions to involve the trunk and extremities, and, in one case, the stable but recalcitrant course over 30 years. In addition, the second patient developed paraneoplastic dermatomyositis. We also retrospectively review our database for other cases that represent the entity of primary cutaneous acral CD8-positive T-cell lymphoproliferative disorder and review the literature focusing on non-acral cases. Nomenclature evolution from its first recognition in 2007 to the present is discussed.

A comparison of the International Consensus and 5th WHO classifications of T-cell lymphomas and histiocytic/dendritic cell tumours

Since the publication in 2017 of the revised 4th Edition of the World Health Organization (WHO) classification of haematolymphoid tumours, here referred to as WHO-HAEM4, significant clinicopathological, immunophenotypic and molecular advances have been made in the field of lymphomas, contributing to refining the diagnostic criteria of several diseases, upgrading entities previously defined as provisional and identifying new entities. This process has resulted in two recent classification proposals of lymphoid neoplasms: the International Consensus Classification (ICC) and the 5th edition of the WHO classification (WHO-HAEM5). In this paper, we review and compare the two classifications in terms of diagnostic criteria and entity definition, focusing on T-cell lymphomas and histiocytic/dendritic cell tumours. Moreover, we update the genetic data of the various pathological entities. The main goal is to provide a tool to facilitate the work of the pathologists, haematologists and researchers involved in the diagnosis and treatment of these haematological malignancies.

The enigmatic ear: Unveiling a rare case of a primary cutaneous CD8+ acral T-cell lymphoproliferative disorder with a literature review

Introduction: Primary cutaneous CD8+ acral T-cell lymphoproliferative disorder (CD8+ ATCLPD) is a rare form of cutaneous T-cell lymphoma that commonly presents on the acral regions of the body. We report a case of a 61-year-old man diagnosed with primary cutaneous CD8+ ATCLPD of the ear. Case presentation: A 61-year-old man presented with a non-healing, erythematous painful macule on the ear that had been evolving for the past 3 months. The lesion was resected, and histopathological examination revealed a primary cutaneous CD8+ ATCLPD with acral localization. Further investigations including CT scan of the thorax, abdomen and pelvis were done to stage the disease. The results showed no extracutaneous involvement. Conclusion: Accurate identification of primary cutaneous CD8+ ATCLPD is crucial due to its distinct prognostic and therapeutic implications compared to other CD8+ cytotoxic lymphoid proliferations. Primary cutaneous CD8+ ATCLPD can be treated conservatively and typically follows a slow clinical course, regardless of the treatment method. Understanding the clinical context, as well as the morphological and immunophenotypic characteristics, can assist in making a precise diagnosis.

Aggressive Cutaneous Lymphomas and Their Mimics

Cutaneous lymphomas encompass a heterogeneous group of neoplasms with a wide spectrum of clinical presentations, histopathologic features, and prognosis. Because there are overlapping pathologic features among indolent and aggressive forms and with systemic lymphomas that involve the skin, clinicopathologic correlation is essential. Herein, the clinical and histopathologic features of aggressive cutaneous B- and T-cell lymphomas are reviewed. Indolent cutaneous lymphomas/lymphoproliferative disorders, systemic lymphomas, and reactive processes that may mimic these entities are also discussed. This article highlights distinctive clinical and histopathologic features, increases awareness of rare entities, and presents new and evolving developments in the field.

The International Consensus Classification of Mature Lymphoid Neoplasms: a report from the Clinical Advisory Committee

Since the publication of the Revised European-American Classification of Lymphoid Neoplasms in 1994, subsequent updates of the classification of lymphoid neoplasms have been generated through iterative international efforts to achieve broad consensus among hematopathologists, geneticists, molecular scientists, and clinicians. Significant progress has recently been made in the characterization of malignancies of the immune system, with many new insights provided by genomic studies. They have led to this proposal. We have followed the same process that was successfully used for the third and fourth editions of the World Health Organization Classification of Hematologic Neoplasms. The definition, recommended studies, and criteria for the diagnosis of many entities have been extensively refined. Some categories considered provisional have now been upgraded to definite entities. Terminology for some diseases has been revised to adapt nomenclature to the current knowledge of their biology, but these modifications have been restricted to well-justified situations. Major findings from recent genomic studies have impacted the conceptual framework and diagnostic criteria for many disease entities. These changes will have an impact on optimal clinical management. The conclusions of this work are summarized in this report as the proposed International Consensus Classification of mature lymphoid, histiocytic, and dendritic cell tumors.

Primary cutaneous CD8+ cytotoxic T-cell lymphoma of the face with intraoral involvement, presenting facial nerve palsy after chemotherapy

The primary cutaneous (PC) CD8+ T-cell lymphoproliferative disorders (LPDs) comprise clinically and histologically heterogeneous entities including mycosis fungoides, lymphomatoid papulosis, hydroa-vacciniforme-like LPD, subcutaneous panniculitis-like T-cell lymphoma (TCL), PC acral CD8+ TCL, PC CD8+ aggressive epidermotropic cytotoxic TCL, and PC peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS). We describe a 33-year-old man who presented progressive facial swelling and lower lip involvement one year ago. Microscopy revealed an atypical small to medium-sized lymphoid proliferation exhibiting perivascular accentuation, adnexotropism and apoptotic cell debris, without surface epithelium involvement. The tumor cells were positive for CD3, CD8, granzyme B, perforin, MUM1/IRF4, and TCR-BF1. The Ki-67 labeling index was 48%. EBER1/2 was negative. Additional studies confirmed localized disease. The diagnosis favored PC-PTCL-NOS. Two months after completing chemotherapy, right-sided facial nerve palsy was diagnosed. CD8+ T-cell LPDs should be considered in the differential diagnosis when assessing facial swelling with intraoral involvement. This article is protected by copyright. All rights reserved.

Clinical, histopathological and prognostic features of primary cutaneous acral CD8+ T-cell lymphoma and other dermal CD8+ cutaneous lymphoproliferations - Results of an EORTC Cutaneous Lymphoma Group Workshop

BACKGROUND

The differential diagnosis of atypical dermal non-epidermotropic CD8+lymphocytic infiltrates includes a heterogenous spectrum of lymphoproliferations with overlapping histological and phenotypic features, but divergent clinical manifestations and prognoses. As these neoplasms are rare, more data on their clinicopathological presentation and course are needed.

OBJECTIVES

To assess the clinical, histological, immunophenotypic features, outcome of and differences between dermal CD8+ lymphoproliferations.

METHODS

Retrospective analysis of a series of 47 patients and biopsies by the international EORTC Cutaneous Lymphoma Group.

RESULTS

The dermal CD8+ lymphoproliferations (n=46) could be assigned to one of the following 3 groups: (1) cutaneous acral CD8+ T-cell lymphoma (n=31), characterized mostly by a solitary nodule arising at acral sites, a monotonous dermal infiltrate of small to medium-sized CD8+ lymphocytes with a characteristic dot-like pattern of CD68, a low proliferation rate and an excellent prognosis; (2) primary cutaneous CD8+ peripheral T-cell lymphoma, unspecified/NOS (n=11), presenting with one or multiple rapidly evolving tumors, mostly medium-sized pleomorphic CD8+ tumor cells with expression of several cytotoxic markers and high proliferative activity. After chemotherapy or radiotherapy relapses occurred in one third and 1 of 11 patients died due to lymphoma (9%); (3) The third group (n=4) comprised cutaneous CD8+ lymphoproliferations associated with congenital immunodeficiency syndromes in 2 patients with persisting localized or disseminated violaceous to brownish plaques on the extremities, a histiocyte-rich infiltrate of mostly small CD8+ lymphocytes with subtle atypia and a protracted course, and papular CD8+ eruptions in two patients with acquired immunosuppression (HIV-infection, solid organ transplantation).

CONCLUSIONS

A constellation of distinct clinical, histopathologic and phenotypic features allows discrimination and assignment of dermal CD8+ infiltrates to distinct disease entities including cutaneous acral CD8+ T-cell lymphoma, primary cutaneous CD8+ peripheral T-cell lymphoma, unspecified/NOS and cutaneous CD8+ lymphoproliferations associated with congenital or acquired immunodeficiency syndromes. Primary cutaneous acral CD8+ lymphoma, assigned a provisional category in current lymphoma classifications, is a distinct and reproducible entity. A correct diagnosis is essential to avoid unnecessarily aggressive treatment for indolent CD8+ lymphoproliferations and to identify cases with underlying immunodeficiency or potential for dismal outcome.

Prominent Blasts in Primary Cutaneous CD4+ Small/Medium T-Cell Lymphoproliferative Disorder. A Reconsideration of Diagnostic Criteria

ABSTRACT

Primary cutaneous CD4+ small/medium T-cell lymphoproliferative disorder (PCSM-LPD), recently downgraded from a T-cell lymphoma, is a poorly characterized histopathological entity. Presenting as a solitary lesion that often grows rapidly, it may raise suspicion for a cutaneous B-cell lymphoma. However, classically, the dermal lymphoid proliferation is predominantly CD4+ with a follicular T-helper profile and a smaller B-cell fraction. Diagnostic uncertainty may arise when B cells are present in large numbers, a B-cell clone is present, or large cell populations are seen. To meet the diagnostic criterion of PCSM-LPD, large cells should not constitute more than 30% of the infiltrate. The 2 cases presented in this article caused diagnostic uncertainty owing to the observation of high numbers of large cells and in one case the presence of a B-cell clone, on the background of otherwise typical clinicopathological features of PCSM-LPD. We review the literature specifically regarding the prevalence of large cell populations and their immunophenotypic characteristics and in light of this discuss whether a current diagnostic criterion should be reconsidered.

Indolent CD8+ primary cutaneous T-cell lymphoma involving the eyelid of an adolescent

Primary cutaneous acral CD8+ T-cell lymphoma (PCACTL) is currently a provisional entity defined as a rare cutaneous proliferation of atypical CD8+ lymphocytes that preferentially involves acral sites and has a good prognosis. We present a case of primary cutaneous CD8+ T-cell lymphoma involving the eyelid of an adolescent male. The case shares features with PCACTL, including indolent clinical behavior and expression of CD68 in a Golgi-associated dot-like pattern; however, other features differ significantly from PCACTL as currently defined by the World Health Organization (WHO). These features include ulceration, expression of CD56, granzyme B, and perforin, and a high proliferative index. Given these discrepancies, our case is currently best classified as a CD8+ primary cutaneous peripheral T-cell lymphoma, not otherwise specified. We review the differential diagnosis for this case and suggest expanding the definition of PCACTL.

Primary cutaneous T-cell lymphomas other than Mycosis Fungoides and Sezary Syndrome - Part I: Clinical and histologic features and diagnosis

Primary cutaneous T-cell lymphomas (CTCLs) are defined as lymphomas with a T-cell phenotype that present in the skin without evidence of systemic or extracutaneous disease at initial presentation. CTCLs other than Mycosis Fungoides (MF) and Sézary syndrome (SS) account for approximately one-third of CTCLs and encompass a heterogenous group of non-Hodgkin lymphomas ranging from indolent lymphoproliferative disorders to aggressive malignancies with a poor prognosis. The spectrum of CTCLs continues to broaden as new provisional entities are classified. Given the morphologic and histologic overlap among CTCLs and other diagnoses, a thorough clinical history, physical evaluation, and clinicopathologic correlation are essential in the workup and diagnosis of these rare entities. This article will summarize the epidemiologic, clinical, pathologic, and diagnostic features of CTCLs other than MF and SS.

Rare T-Cell Subtypes

There are a number of rare T-cell lymphoma subtypes that may be encountered in clinical practice. In recent years, improved immunohistochemical techniques and molecular tumor profiling have permitted refinement of some of the diagnostic categories in this group, as well as the recognition of distinct conditions not previously well elucidated. In this chapter, we cover the diagnostic and clinical features of some of the more common of these conditions, including subcutaneous panniculitis-like T-cell lymphoma, cutaneous gamma-delta T-cell lymphoma, enteropathy-associated T-cell lymphoma, monomorphic epitheliotropic intestinal T-cell lymphoma, primary cutaneous CD8-positive aggressive epidermotropic cytotoxic T-cell lymphoma, CD4-positive small/medium T-cell lymphoproliferative disorder, and acral CD8-positive T-cell lymphoma. Given the rarity of these conditions, optimal treatments approaches are not always well established, not least as data from large-scale clinical trials are lacking. In this chapter, we aim to provide a summation of current thinking around best treatment, as well as highlighting some controversies in the management of these diagnoses.

New Therapies and Immunological Findings in Cutaneous T-Cell Lymphoma

Primary cutaneous lymphomas comprise a group of lymphatic malignancies that occur primarily in the skin. They represent the second most common form of extranodal non-Hodgkin’s lymphoma and are characterized by heterogeneous clinical, histological, immunological, and molecular features. The most common type is mycosis fungoides and its leukemic variant, Sézary syndrome. Both diseases are considered T-helper cell type 2 (Th2) diseases. Not only the tumor cells but also the tumor microenvironment can promote Th2 differentiation, which is beneficial for the tumor cells because a Th1 environment enhances antitumor immune responses. This Th2-dominant milieu also underlies the infectious susceptibility of the patients. Many components, such as tumor-associated macrophages, cancer-associated fibroblasts, and dendritic cells, as well as humoral factors, such as chemokines and cytokines, establish the tumor microenvironment and can modify tumor cell migration and proliferation. Multiagent chemotherapy often induces immunosuppression, resulting in an increased risk of serious infection and poor tolerance. Therefore, overtreatment should be avoided for these types of lymphomas. Interferons have been shown to increase the time to next treatment to a greater degree than has chemotherapy. The pathogenesis and prognosis of cutaneous T-cell lymphoma (CTCL) differ markedly among the subtypes. In some aggressive subtypes of CTCLs, such as primary cutaneous gamma/delta T-cell lymphoma and primary cutaneous CD8⁺ aggressive epidermotropic cytotoxic T-cell lymphoma, hematopoietic stem cell transplantation should be considered, whereas overtreatment should be avoided with other, favorable subtypes. Therefore, a solid understanding of the pathogenesis and immunological background of cutaneous lymphoma is required to better treat patients who are inflicted with this disease. This review summarizes the current knowledge in the field to attempt to achieve this objective.

Primary Cutaneous Acral CD8+ T-Cell Lymphoma

Primary cutaneous acral CD8+ T-cell lymphoma is a new provisional entity in the 2016 revision of the World Health Organization classification of lymphoid neoplasms. This is a challenging diagnosis because of its rarity, as well as its morphologic and immunophenotypic overlap with other CD8+ cytotoxic lymphoid proliferations. Appropriate classification of this entity is crucial because of its indolent clinical behavior compared with other CD8+ T-cell lymphomas. Knowledge of the clinical setting, sites of involvement, and morphologic features can aid in correct diagnosis. Here, we review the clinical and pathologic features of primary cutaneous acral CD8+ T-cell lymphoma with an emphasis on the differential diagnosis among other C8+ T-cell lymphomas.

Primary cutaneous acral CD8 positive T-cell lymphoma with extra-cutaneous involvement: A long-standing case with an unexpected progression

Primary cutaneous acral CD8+ T-cell lymphoma (acral CD8+ TCL) is a new provisional entity characterized by acral skin lesions and an indolent course. We describe an extraordinary case characterized by relapsed nodules with CD8+ cytotoxic infiltrates on the left ear. After 35 years, the skin lesions spread to other acral sites, and a mass with the same histological features as the other skin lesions appeared on the nose. Multiple courses of chemotherapy led to stable disease. Histological examinations carried out at different times showed the gradual transformation of the neoplastic cells, with an increased proliferation index. Genomic analysis revealed losses in the regions harboring the genes involved in cell cycle control. This is the first case of an acral CD8+ TCL with a very long history of indolent nodular lesions progressing to extra-cutaneous sites.

CD68 expression is a discriminative feature of indolent cutaneous CD8-positive lymphoid proliferation and distinguishes this lymphoma subtype from other CD8-positive cutaneous lymphomas

BACKGROUND

Indolent cutaneous CD8+ lymphoid proliferation is a recently described rare entity among cutaneous T-cell lymphomas that typically presents with solitary skin lesions at acral sites. Separation from otherwise aggressive T-cell lymphomas bearing a cytotoxic CD8+ phenotype is fundamental to avoid unnecessary harmful treatment. However, up to now, no reliable discriminative marker has been identified.

OBJECTIVES

Motivated by these diagnostic quandaries, we have analyzed a large series of archived formalin-fixed paraffin-embedded (FFPE) specimens of atypical CD8+ cutaneous infiltrates with clear-cut diagnosis and clinical follow-up (n = 44) including five cases of indolent CD8+ lymphoid proliferation by using immunohistochemistry with the aim of obtaining markers predictive of subtype assignment.

RESULTS

We identified exclusive expression of CD68 by lymphoma cells within the subgroup of indolent CD8+ lymphoid proliferation (5/5 cases). Specific CD68 expression in this entity was confirmed by the application of several monoclonal antibodies (KP1, PG-M1, KiM1P) against the CD68 molecule available for FFPE tissue. In contrast, none of the infiltrates of the other CD8+ cutaneous lymphoma entities stained positive for CD68 (0/39).

CONCLUSIONS

Based on these observations, we suggest CD68 as a new discriminative marker which is helpful in distinguishing indolent CD8+ lymphoid proliferation from other CD8+ cutaneous lymphomas in ambiguous cases.

Multicenter case series of indolent small/medium-sized CD8+ lymphoid proliferations with predilection for the ear and face

We report 7 cases of a CD8 lymphoid proliferation of the ear and face with a cytotoxic T-cell phenotype, but an indolent clinical course. All patients presented with stable or slowly growing asymptomatic lesions on the ear, nose, or lower eyelid. Histopathology showed a dense diffuse dermal infiltrate of small- to medium-sized atypical lymphocytes without destructive features. The lymphocytes were positive for CD3, CD8, β-F1, and TIA-1 and negative for CD4, CD30, CD56, granzyme B, and PD-1. Of note, the proliferation index was low in available cases. All patients remained in complete remission at median follow-up of 14 months regardless of treatment modality. Staging was negative for extracutaneous disease in all patients. The clinically indolent behavior and histopathologic phenotype together with a low proliferation index (10%-15%) emphasize the importance of accurate diagnosis and appropriate clinical management to avoid overtreatment and complications of therapy.

Cytotoxic T-cell and NK-cell lymphomas: current questions and controversies

The cytotoxic T-cell and natural killer (NK)-cell lymphomas and related disorders are important but relatively rare lymphoid neoplasms that frequently are a challenge for practicing pathologists. This selective review, based on a meeting of the International Lymphoma Study Group, briefly reviews T-cell and NK-cell development and addresses questions related to the importance of precise cell lineage (αβ-type T cell, γδ T cell, or NK cell), the implications of Epstein-Barr virus infection, the significance of anatomic location including nodal disease, and the question of further categorization of enteropathy-associated T-cell lymphomas. Finally, developments subsequent to the 2008 World Health Organization Classification, including the recognition of indolent NK-cell and T-cell disorders of the gastrointestinal tract are presented.

Indolent CD8+ lymphoid proliferation of the face with eyelid involvement

In 2007, Petrella et al described a series of patients with clonally restricted, well-differentiated, nonepidermotropic, CD8-dominant lymphocytic infiltrates localized to the facial area. The clinical course described was indolent. A CD8 variant of primary cutaneous pleomorphic T-cell lymphoma has been proposed; however, there are many dissimilar features. The authors encountered 2 patients with CD8⁺ indolent lymphoid proliferation of the face, localized to the eyelid. Both patients were males in their 30s presenting with localized lesions of the eyelids. The biopsies showed an effacing lymphocytic infiltrate that spanned the sampled dermis. The lymphocytes were well differentiated, exhibiting mild nuclear contour irregularity. The infiltrate was predominated by CD8⁺ lymphocytes demonstrating TIA expression. There was a minimal B-cell component in 1 case, whereas another showed a significant degree of B-cell hyperplasia. They both underwent complete excision without recurrence. CD8⁺ indolent lymphoid proliferation has a reproducible clinical and morphologic presentation that warrants categorization as a distinct form of indolent lymphoproliferative disease, preferentially involving older adults with the most common site being the ear, recognizing that the nose, acral surfaces, and eyelids can also be involved.

CD30-Negative Cutaneous T-Cell Lymphomas Other than Mycosis Fungoides

Cutaneous T-cell lymphomas (CTCLs), other than mycosis fungoides/Sézary syndrome and the group of cutaneous CD30(+) lymphoproliferative disorders, are rare. These include subcutaneous panniculitis-like T-cell lymphoma (SPTCL); extranodal natural killer/T-cell lymphoma, nasal type; primary cutaneous peripheral T-cell lymphoma, not otherwise specified (PTCL, NOS); and rare subtypes of PTCL, NOS. Apart from SPTCL and primary cutaneous CD4-positive small-medium pleomorphic T-cell lymphoma, these lymphomas have in common aggressive clinical behavior and poor prognosis. Differentiation between these different types of CTCL may be difficult and requires integration of histopathologic findings with clinical data and the results of phenotypic and often molecular genetic studies.

Extrafacial indolent CD8-positive cutaneous lymphoid proliferation with unusual symmetrical presentation involving both feet

Indolent CD8+ cutaneous lymphoid proliferation represents a recently described entity among cutaneous T-cell lymphomas that typically presents with solitary skin lesions on the face or at acral sites and usually follows an indolent clinical course. Histopathologically, this entity is characterized by a dense dermal infiltrate of non-epidermotropic, small- to medium-sized pleomorphic CD8+ T-cells of the non-activated cytotoxic phenotype showing a clear-cut grenz zone and a low proliferation index. Distinction from otherwise aggressive T-cell lymphomas bearing a cytotoxic CD8+ phenotype is fundamental. We herein present an unusual case of indolent CD8+ cutaneous lymphoid proliferation presenting in bilateral symmetrical distribution on both feet and lacking the otherwise described grenz zone. Our case widens the spectrum of possible clinical and histomorphological variations of this entity. Taking into account the distinctive and unique clinical and microscopic features of all hitherto published cases of indolent CD8+ cutaneous lymphoid proliferation we suppose that this lymphoma subtype has to be included as a new and distinct entity in the World Health Organisation (WHO)-/European Organisation for Research and Treatment of Cancer (EORTC)-classification of cutaneous lymphomas.