Cutaneous B-cell lymphoproliferative disorders: report of the 2011 Society for Hematopathology/European Association for Haematopathology workshop

Lymphocytoma cutis (cutaneous B-cell pseudolymphoma): study of 102 cases with emphasis on the histological characteristics and immunohistochemistry of the miliarial type

BACKGROUND

Lymphocytoma cutis (LC) is a benign reactive lymphoproliferative B-cell process. It has two variants: localized type with solitary lesions and miliarial type with numerous lesions. The objective was to investigate the characteristics of LC with emphasis on the miliarial type.

METHODS

Retrospective study, patients with clinical and histopathological diagnosis of LC were included. Age, sex, evolution time, affected site, and type of treatment were investigated. In miliarial-type LC, the histological and immunohistochemical characteristics were also investigated.

RESULTS

In an 18-year period, there were 102 patients found with LC: 72 (71%) corresponded to females, the median age was 45 years, the median evolution time was 4 months, and the face was the most predominant affected area in 81 (79%) cases. Localized-type LC corresponded to 88 (86%) cases, and miliarial type in 14 (14%). The most common treatment was surgery, which was used in 32 (31%) patients, all of whom had localized type (P < 0.01). The most frequent treatment for miliarial-type LC was corticosteroids in five (36%, P = 0.32), the predominant histopathological pattern was nodular in 10 (71%) specimens, and immunohistochemistry was performed in 11 (79%), where all were positive for CD20 with polyclonality to kappa and lambda light chains.

CONCLUSIONS

The importance of LC lies in that it can be clinically and histopathologically confused with cutaneous lymphoma and that it is a rare entity, with its miliarial variant being rarer still. This study provides information on the clinical-histological characteristics of LC and its immunohistochemistry.

Cutaneous B-cell lymphomas: 2021 update on diagnosis, risk-stratification, and management

DISEASE OVERVIEW

Approximately one-fourth of primary cutaneous lymphomas are B-cell derived and are generally classified into three distinct subgroups: primary cutaneous follicle center lymphoma (PCFCL), primary cutaneous marginal zone lymphoma (PCMZL), and primary cutaneous diffuse large B-cell lymphoma, leg type (PCDLBCL, LT).

DIAGNOSIS

Diagnosis and disease classification is based on histopathologic review and immunohistochemical staining of an appropriate skin biopsy. Pathologic review and an appropriate staging evaluation are necessary to distinguish primary cutaneous B-cell lymphomas from systemic B-cell lymphomas with secondary skin involvement.

RISK-STRATIFICATION

Disease histopathology remains the most important prognostic determinant in primary cutaneous B-cell lymphomas. Both PCFCL and PCMZL are indolent lymphomas that infrequently disseminate to extracutaneous sites and are associated with 5-year survival rates that exceed 95%. In contrast, PCDLBCL, LT is an aggressive lymphoma with an inferior prognosis.

RISK-ADAPTED THERAPY

Both PCFCL and PCMZL patients with solitary or relatively few skin lesions may be effectively managed with local radiation therapy. While single-agent rituximab may be employed for patients with more widespread skin involvement, multi-agent chemotherapy is rarely appropriate. In contrast, management of patients with PCDLBCL, LT is comparable to the management of patients with systemic DLBCL.

How I Diagnose Primary Cutaneous Marginal Zone Lymphoma

OBJECTIVES

Primary cutaneous marginal zone lymphoma (PCMZL) is 1 of the 3 major subtypes of primary cutaneous B-cell lymphoma. The diagnosis of PCMZL may be challenging, as the differential diagnosis includes benign cutaneous lymphoproliferations as well as other primary or secondary cutaneous B-cell or T-cell lymphomas. This review describes our approach to the diagnosis of PCMZL.

METHODS

Two cases are presented that illustrate how we diagnose each of the 2 subtypes of PCMZL. The clinicopathologic features of PCMZL and the ways in which these cases can be distinguished from both benign and other neoplastic entities are emphasized.

RESULTS

A definitive diagnosis of PCMZL requires the incorporation of histologic and immunophenotypic features, molecular genetic studies in some cases, and just as importantly, clinical findings. Emerging data suggest that the heavy chain class-switched cases may be more like a clonal chronic lymphoproliferative disorder.

CONCLUSIONS

The 2 subtypes of PCMZL create different diagnostic challenges and require the use of a multiparameter approach. Although very indolent, it is important to distinguish PCMZLs from reactive proliferations, because they frequently recur and may require antineoplastic therapies. It is also critical to distinguish PCMZLs from other B- or T-cell lymphomas so that patients are properly evaluated and not overtreated.

A review of EBV-positive mucocutaneous ulcers focusing on clinical and pathological aspects

Epstein-Barr virus (EBV)-positive mucocutaneous ulcers (EBVMCUs) were first described as a lymphoproliferative disorder in 2010. Clinically, EBVMCUs are shallow, sharply circumscribed, unifocal mucosal or cutaneous ulcers that occur in immunosuppressed patients, including those with advanced age-associated immunosenescence, iatrogenic immunosuppression, primary immune disorders, and HIV/AIDS-associated immune deficiencies. In general, patients exhibit indolent disease progression and spontaneous regression. Histologically, EBVMCUs are characterized by the proliferation of EBV-positive, variable-sized, atypical B-cells. According to conventional histopathologic criteria, EBVMCUs may diagnosed as lymphomas. However, EBVMCUs are recognized as pseudomalignant lesions because they spontaneously regress without anti-cancer treatment. Therefore, overtreatment must be carefully avoided and multilateral differentiation is important. In this article, we reviewed previously reported EBVMCUs focusing on their clinical and pathological aspects in comparison with other EBV-positive B-cell neoplasms.

Unusual Clinical Presentation of a Primary Cutaneous Follicle Center Lymphoma on the Scalp of a Middle-Aged Female: Case Report and Review of the Literature

Primary cutaneous follicle center lymphoma (PCFCL) is a rare type of indolent, low-grade cutaneous B-cell lymphoma with an excellent prognosis. It usually presents with erythematous nodules and plaques on the head, neck, or back. The diagnosis is primarily based on histopathology, immunohistochemistry, and molecular studies. We describe a case of PCFCL causing a well-defined alopecic atrophic patch. The patch developed in the area of a large subcutaneous nodule that regressed after treatment with rituximab infusion. We hypothesize that the alopecia could have been caused by pressure.

Pathology and diagnosis of follicular lymphoma and related entities

Follicular lymphoma (FL) is an indolent, mature B-cell neoplasm classically characterised by the t(14;18)(q32;q21) with constitutive overexpression of the anti-apoptotic protein, BCL2. Most cases present in older adults with slowly progressive lymphadenopathy and follow an indolent clinical course. Typical morphology shows an expansile follicular proliferation with tumour expression of germinal centre markers, and bone marrow involvement at diagnosis is frequent. However, in the recent past, efforts to understand the biological and clinical heterogeneity of FL has effected significant change to the diagnostic approach. While morphological grade, assessed by enumerating large 'centroblasts' in the neoplastic follicles, generally correlates with outcome in systemic nodal FL, variants with high-grade morphology but indolent clinical behaviour have been identified. Given the clinical implications of these FL variants, knowledge of their clinical and histopathological defining features is of paramount importance to the pathologist. Furthermore, as with many areas of diagnostic oncology, precursors to FL have been identified and described with measurable rates of progression to bona fide lymphoma. Accurate diagnosis of these early lesions can often prevent unnecessary therapy and guide appropriate monitoring for disease progression. This review aims to summarise these key pathological and diagnostic features of FL. We further highlight the biological underpinnings of FL that will likely affect the classification, diagnosis, and treatment of patients with lymphoma.

Primary Cutaneous Follicle Center Lymphoma

CONTEXT.—

Primary cutaneous follicle center lymphoma is a low-grade B-cell lymphoma that is limited to the skin at diagnosis. It has a differential diagnosis that includes systemic/nodal follicular lymphoma secondarily involving the skin; primary cutaneous diffuse large B-cell lymphoma leg type; reactive lymphoid hyperplasia; and primary cutaneous marginal zone lymphoma.

OBJECTIVE.—

To review the clinical, morphologic, immunophenotypic, and genetic features of primary cutaneous follicle center lymphoma; its differential diagnosis; and the evidence that supports use of immunohistochemistry and genetic testing in the diagnosis and prognosis of this entity.

DATA SOURCES.—

Pertinent literature regarding cutaneous B-cell lymphomas is summarized and University of Michigan cases are used to highlight characteristics of primary cutaneous follicle center lymphoma.

CONCLUSIONS.—

Primary cutaneous follicle center lymphoma is a low-grade B-cell lymphoma with distinctive features, although some cases may have elements that overlap with other lymphomas, complicating interpretation.

Update on Gastrointestinal Lymphomas

Herein we review the following selection of gastrointestinal lymphomas: monomorphic epitheliotropic intestinal T-cell lymphoma; indolent T-cell lymphoproliferative disorder of the gastrointestinal tract; intestinal T-cell lymphoma, not otherwise specified; duodenal-type follicular lymphoma; and Epstein-Barr virus-positive mucocutaneous ulcer. Definitions reflect the 2016 revision of the World Health Organization classification of lymphoid neoplasms. Clinical, morphologic, and immunophenotypic characteristics of each entity are emphasized.

The 2018 update of the WHO-EORTC classification for primary cutaneous lymphomas

Primary cutaneous lymphomas are a heterogeneous group of T- and B-cell lymphomas that present in the skin with no evidence of extracutaneous disease at the time of diagnosis. The 2005 World Health Organization-European Organization for Research and Treatment of Cancer (WHO-EORTC) consensus classification has served as a golden standard for the diagnosis and classification of these conditions. In September 2018, an updated version of the WHO-EORTC was published in the fourth edition of the WHO Classification of Skin Tumours Blue Book. In this classification, primary cutaneous acral CD8⁺ T-cell lymphoma and Epstein-Barr virus positive (EBV⁺) mucocutaneous ulcer are included as new provisional entities, and a new section on cutaneous forms of chronic active EBV disease has been added. The term "primary cutaneous CD4⁺ small/medium T-cell lymphoma" was modified to "primary cutaneous CD4⁺ small/medium T-cell lymphoproliferative disorder" because of its indolent clinical behavior and uncertain malignant potential. Modifications have also been made in the sections on lymphomatoid papulosis, increasing the spectrum of histologic and genetic types, and primary cutaneous marginal zone lymphomas recognizing 2 different subtypes. Herein, the characteristic features of these new and modified entities as well as the results of recent molecular studies with diagnostic, prognostic, and/or therapeutic significance for the different types of primary cutaneous lymphomas are reviewed. An update of the frequency and survival of the different types of primary cutaneous lymphomas is provided.

Double-hit or dual expression of MYC and BCL2 in primary cutaneous large B-cell lymphomas

In nodal diffuse large B-cell lymphoma, the search for double-hit with MYC and BCL2 and/or BCL6 rearrangements or for dual expression of BCL2 and MYC defines subgroups of patients with altered prognosis that has not been evaluated in primary cutaneous large B-cell lymphoma. Our objectives were to assess the double-hit and dual expressor status in a cohort of 44 patients with primary cutaneous large B-cell lymphoma according to the histological subtype and to evaluate their prognosis relevance. The 44 cases defined by the presence of more than 80% of large B-cells in the dermis corresponded to 21 primary cutaneous follicle centre lymphoma with large cell morphology and 23 primary cutaneous diffuse large B-cell lymphoma, leg type. Thirty-one cases (70%) expressed BCL2 and 29 (66%) expressed MYC. Dual expressor profile was observed in 25 cases (57%) of either subtypes (n = 6 or n = 19, respectively). Only one primary cutaneous follicle centre lymphoma, large-cell case had a double-hit status (2%). Specific survival was significantly worse in primary cutaneous diffuse large B-cell lymphoma, leg type than in primary cutaneous follicle centre lymphoma, large cell (p = 0.021) and for the dual expressor primary cutaneous large B-cell lymphoma group (p = 0.030). Both overall survival and specific survival were worse for patients belonging to the dual expressor primary cutaneous diffuse large B-cell lymphoma, leg type subgroup (p = 0.001 and p = 0.046, respectively). Expression of either MYC and/or BCL2 negatively impacted overall survival (p = 0.017 and p = 0.018 respectively). As the differential diagnosis between primary cutaneous follicle centre lymphoma, large cell and primary cutaneous diffuse large B-cell lymphoma, leg type has a major impact on prognosis, dual-expression of BCL2 and MYC may represent a new diagnostic criterion for primary cutaneous diffuse large B-cell lymphoma, leg type subtype and further identifies patients with impaired survival. Finally, the double-hit assessment does not appear clinically relevant in primary cutaneous large B-cell lymphoma.

Cutaneous Hematolymphoid and Histiocytic Proliferations in Children

This article focuses on cutaneous hematopoietic neoplasms that are more likely to be encountered in the pediatric age-group and includes both lymphoproliferative and histiocytic disorders. The cutaneous hematologic disorders in children have a different epidemiologic profile to what is seen during adulthood. Although mycosis fungoides is the most frequent form of cutaneous lymphoma in adults, it is very rare in children. Because lymphoblastic leukemias and lymphomas are more frequent in the pediatric setting, cutaneous leukemic infiltrates are relatively common in this age-group. Similarly, histiocytic disorders are more common in children, particularly Langerhans cell histiocytosis and juvenile xanthogranuloma. Notably, the histiocytic disorders have undergone significant modifications on their nomenclature in the basis of the molecular characteristics that are present in them. A summary of the most frequent cutaneous hematopoietic disorders in children will be discussed further in this review.

Primary cutaneous B-cell lymphoma: narrative review of the literature

Primary cutaneous B-cell lymphomas comprehend a group of lymphoproliferative disorders characterized by being monoclonal proliferations of B-cell primarily involving the skin. Despite being recognized as autonomous and distinct clinico-pathologic entities since the late 80s, their classification is still an ongoing matter of debate. At the moment, WHO classification recognizes three disorders: primary cutaneous marginal zone lymphoma, primary cutaneous follicle center lymphoma and primary cutaneous diffuse large b-cell lymphoma (leg type). Primary cutaneous diffuse large b-cell lymphoma (other) has been used to define rare cases which show histologically an infiltrate with diffuse pattern composed by large b-cell, but not fitting with criteria for follicle center lymphoma nor for primary cutaneous diffuse large b-cell lymphoma (leg type). Aim of this review was to briefly describe all recognized and provisional entities included in the primary cutaneous b-cell lymphomas and to discuss recent acquisitions that may influence their future classifications.

Overview on the management of non-gastric MALT lymphomas

Extranodal marginal zone B-cell lymphomas (EMZLs) of the mucosa-associated lymphoid tissue (MALT) are indolent lymphomas which can present at any extranodal site. The most frequent localizations (other than stomach) are ocular adnexa, salivary gland, skin, lung and thyroid. Chronic inflammation and antigenic stimulation are a potential risk for the development of MALT lymphomas. While Helicobacter Pylori (HP) is known to be associated with gastric MALT lymphoma and antibiotic therapy is effective in the setting of HP-positive, other microorganisms (such as Chlamydophila Psittaci, Campylobacter Jejiuni, Borrelia Burgdoferi) have been implicated in the pathogenesis of non-gastric MALT lymphomas. However, antibiotic therapy has not been extensively investigated for the non-gastric type, except for ocular adnexal MALT lymphoma, which could benefit from an upfront treatment with doxycycline. Surgery, radiotherapy, Rituximab alone or in combination with chemotherapy and "chemo-free" approaches, including lenalidomide, have shown efficacy in the treatment of non-gastric MALT lymphomas.

A distinctive subgroup of oral EBV+ B-cell neoplasm with polymorphous features is potentially identical to EBV+ mucocutaneous ulcer

Epstein-Barr virus-positive mucocutaneous ulcer (EBVMCU) is a newly recognized provisional entity included in mature B-cell neoplasm in the latest 2016 World Health Organization Classification. It has a self-limited growth potential with a high predilection for oral cavities and occurs in age-related or iatrogenic immunodeficiency with indolent clinical courses. However, it shares histological features with EBV-positive diffuse large B-cell lymphoma (DLBCL), and this often leads to diagnostic challenges and controversies in patients with an oral EBV-positive B-cell neoplasm. The aim of this study was to better characterize and comprehend the pathophysiology of DLBCL and EBVMCU in the oral cavity. We conducted clinicopathologic and recurrent gene mutation analysis of 49 cases (14 EBV positive, 35 EBV negative), including cases diagnosed as DLBCL or B-cell lymphoproliferative disorders with high-grade morphology in the oral cavity. All EBV-positive cases matched the criteria of EBVMCU, with significantly earlier clinical stages than the EBV-negative group (P=.0006). Besides, histological analysis showed that all EBV-positive cases presented polymorphous features, whereas 91.4% (32/35) of the EBV-negative cases showed diffuse and monotonous proliferation (P<.0001). Furthermore, EBV-positive cases presented favorable clinical outcomes without disease-related death or recurrence. Gene mutation analysis (MYD88, CD79A, CD79B, CARD11, and EZH2) revealed that 33.3% (9/27) of EBV-negative cases harbored at least 1 gene mutation, whereas no gene mutation was observed in the EBV-positive group (0/11). These results suggest that oral EBV-positive B-cell lymphoid proliferation with polymorphous features often fulfill the criteria for EBVMCU, with clinicopathologically and genetically distinctive properties.

[Diffuse large B-cell lymphoma with concomitant c-MYC and BCL6 gene rearrangements with primary skin involvement: A case report and a review of literature]

Double-hit lymphoma (DHL) is a rare aggressive B-cell lymphoma with concomitant c-MYC, BCL2 or BCL6 gene rearrangements, which is characterized by the high frequency of extranodal lesions and by resistance to chemotherapy. The median survival does not exceed 18 months in patients with this disease. The majority of DHL is represented by с-MYC/BCL2 cases. The combination of c-MYC/BCL6 occurs rarely (5-8%). The paper describes a case of DHL with concomitant c-MYC and BCL6 gene rearrangements, which mimics diffuse large B-cell lymphoma, leg-type.

Epstein-Barr Virus-associated Mucocutaneous Ulcer in a Patient With T-Cell Acute Lymphoblastic Leukemia: Importance of Accurate Diagnosis and Conservative Management

Epstein-Barr virus-associated mucocutaneous ulcer (EBV-MCU) is a recently characterized entity that falls under the spectrum of EBV-lymphoproliferative disorders. First described in 2010 by Dojcinov et al, it is an EBV-driven localized proliferation of B cells, occurring in mucocutaneous tissues including the skin, the oropharynx, and the gastrointestinal tract of immunosuppressed patients in the absence of an intact T-cell repertoire. Typically, it has been described in elderly patients with age-related immunosenescence and patients who are on immunosuppressive therapy. However, only 2 cases have been reported in pediatric, adolescent, and young adult age groups, with all these patients manifesting after solid organ transplant. To the best of our knowledge there are no case reports of EBV-MCU occurring in association with hematologic malignancy. Here, we present a case of EBV-MCU in a young adult patient with T-cell acute lymphoblastic leukemia. Our report serves to promote awareness among clinicians regarding this newly described and extremely rare clinical entity in young immunosuppressed patients. In addition, we highlight the importance of accurate diagnosis to prevent overtreatment of this indolent, often self-resolving disease that has a significant clinicopathologic overlap with other aggressive forms of EBV-lymphoproliferative disorders that require more intensive therapy.

A rare case of Epstein-Barr virus mucocutaneous ulcer of the colon

Epstein-Barr virus mucocutaneous ulcer (EBVMCU) is a rare form of EBV lymphoproliferative disorder. The disease was recently described in 2010 for the first time in a case series and it was recently identified by the WHO classification of haematological malignancies as a separate category among the EBV lymphoproliferative disorders. We present a case of EBVMCU of the colon presenting as an ulcerating inflammatory mass in a female in her mid-60s who presented initially with abdominal pain and diarrhoea. The patient had extensive workup for her disease and due to progression of her symptoms, she was taken for an exploratory laparotomy. During the procedure, there was an inflammatory mass at the caecum and severe inflammation of the caecum and the terminal ileum and right hemicolectomy was performed. Diagnosis was confirmed by histopathology as EBV-positive lymphoproliferative disorder best classified as EBV-positive mucocutaneous ulcer.

Primary cutaneous B-cell lymphoma and chronic leg ulcers in a patient with type 2 diabetes

The incidences of type 2 diabetes mellitus and many cancers are rapidly increasing worldwide. Diabetes is a strong risk factor for some cancers (including lymphomas) and is also associated with adverse cancer outcomes. After gastrointestinal tract, the skin is the second most frequent extranodal site involved by non-Hodgkin lymphomas and the cutaneous B-cell lymphomas (CBCLs) range from 25% to 30% of all primary cutaneous lymphomas. The primary cutaneous diffuse large B-cell lymphoma (PCDLBCL) is an aggressive lymphoma with a poor prognosis, representing roughly 20% of all primary CBCLs. Classically, the cutaneous manifestation of this lymphoma is a red or violaceous tumors arising on a leg. To date, despite the large body of evidence suggesting that diabetes is strongly associated with an increased risk of some cancers, very little information is available regarding a possible association between type 2 diabetes and primary cutaneous diffuse large B-cell lymphoma. In this report, we will present the case of a white adult patient with type 2 diabetes with chronic leg ulcers complicated by a primary cutaneous diffuse large B-cell lymphoma.

A Literature Revision in Primary Cutaneous B-cell Lymphoma

The term “Primary Cutaneous B-Cell Lymphoma” (PCBCL) comprehends a variety of lymphoproliferative disorders characterized by a clonal proliferation of B-cells primarily involving the skin. The absence of evident extra-cutaneous disease must be confirmed after six-month follow-up in order to exclude a nodal non-Hodgkin's lymphoma (NHL) with secondary cutaneous involvement, which may have a completely different clinical behavior and prognosis. In this article, we have summarized the clinico-pathological features of main types of PCBCL and we outline the guidelines for management based on a review of the available literature.

Cutaneous EBV-related lymphoproliferative disorders

This article will focus on the cutaneous lymphoproliferative disorders associated with EBV, with an emphasis on the upcoming changes in the revised 4th Edition of the WHO classification of tumors of the hematopoietic system, many of which deal with cutaneous disorders derived from NK-cells or T-cells. Extranodal NK/T-cell lymphoma usually presents in the upper aerodigestive tract, but can involve the skin secondarily. EBV-associated T- and NK-cell lymphoproliferative disorders (LPD) in the pediatric age group include the systemic diseases, chronic active EBV infection (CAEBV) and systemic EBV+ T-cell lymphoma of childhood. Hydroa vacciniforme (HV)-like LPD is a primarily cutaneous form of CAEBV and encompasses the lesions previously referred to as HV and HV-like lymphoma (HVLL). All the T/NK-cell-EBV-associated diseases occur with higher frequency in Asians, and indigenous populations from Central and South America and Mexico. Among the B-cell EBV-associated LPD two major changes have been introduced in the WHO. The previously designated EBV-positive diffuse large B-cell lymphoma (EBV-DLBCL) of the elderly, has been changed to EBV-DLBCL with 'not otherwise specified' as a modifier (NOS). A new addition to the WHO system is the more recently identified EBV+ mucocutaneous ulcer, which involves skin and mucosal-associated sites.

Cutaneous marginal zone lymphomas

Primary cutaneous marginal zone lymphoma (CMZL) is one of the major primary B-cell lymphomas of skin. Two types are recognized: a more common class-chain switched CMZL, and a much less common IgM+ CMZL. The extremely indolent course, together with other features distinct from most other MALT lymphomas, has led some to question whether at least the class-switched cases should be considered an overt lymphoma.

Clinical features and management of non-gastrointestinal non-ocular extranodal mucosa associated lymphoid tissue (ENMALT) marginal zone lymphomas

Extranodal mucosa associated lymphoid tissue (ENMALT) marginal zone lymphomas may arise at any site of the body. The most frequent localizations other than gastrointestinal and eye are salivary gland, skin, lung and thyroid. These lymphomas usually arise in a setting of inflammation due to a persistent infection or autoimmune diseases such as Sjogren syndrome in salivary MALT lymphomas and Hashimoto's thryroiditis in thyroid lymphomas. They affect middle-aged patients with a female predominance when lymphoma arises in certain locations. Patients often present with localised stage I or II although disseminated disease may be present at diagnosis or relapse in a third of the cases. Biopsy of the affected site is mandatory to establish the diagnosis and a full work-up staging is recommended. The clinical course is indolent and prognosis is good despite that recurrences following response to therapy are frequent. Surgery, radiotherapy and/or Rituximab based regimens are effective in these lymphomas.

Cutaneous primary B-cell lymphomas: from diagnosis to treatment

Primary cutaneous B-cell lymphomas are a heterogeneous group of mature B-cells neoplasms with tropism for the skin, whose biology and clinical course differ significantly from the equivalent nodal lymphomas. The most indolent forms comprise the primary cutaneous marginal zone and follicle center B-cell lymphomas that despite the excellent prognosis have cutaneous recurrences very commonly. The most aggressive forms include the primary cutaneous large B-cell lymphomas, consisting in two major groups: the leg type, with poor prognosis, and others, the latter representing a heterogeneous group of lymphomas from which specific entities are supposed to be individualized over time, such as intravascular large B-cell lymphomas. Treatment may include surgical excision, radiotherapy, antibiotics, corticosteroids, interferon, monoclonal antibodies and chemotherapy, depending on the type of lymphoma and on the type and location of the skin lesions. In subtypes with good prognosis is contraindicated overtreatment and in those associated with a worse prognosis the recommended therapy relies on CHOP-like regimens associated with rituximab, assisted or not with local radiotherapy. We review the primary cutaneous B-cell lymphomas, remembering the diagnostic criteria, differential diagnosis, classification, and prognostic factors and presenting the available therapies.

The Expanding Spectrum of Follicular Lymphoma

Follicular lymphoma is a far more heterogeneous entity than originally appreciated. Clinical and biological variants are increasingly more granularly defined, expanding the spectrum of disease. Some variants associate with age, whereas others with anatomic site. Identification of these biologically distinct diseases has real prognostic and predictive value for patients today and likely will be more relevant in the future. Understanding of follicular lymphoma precursors has also made their identification both scientifically and clinically relevant. This review summarizes the features and understanding of follicular lymphoma, variants, and precursor lesions.

Best practices in diagnostic immunohistochemistry: workup of cutaneous lymphoid lesions in the diagnosis of primary cutaneous lymphoma

CONTEXT

Primary cutaneous lymphoma is a common extranodal non-Hodgkin lymphoma. These lesions share common features with their nodal counterparts, but also have differences in morphology, unique clinical presentations, and immunohistochemical features.

OBJECTIVE

To review the 2008 World Health Organization (WHO) and 2005 consensus WHO-EORTC (European Organisation for Research and Treatment of Cancer) classifications, and address the immunohistochemical findings in the most common primary cutaneous T- and B-cell lymphomas. Since clonality testing is commonly used as an ancillary test in the evaluation of cutaneous lymphoma, a brief section in the use and pitfalls of clonality testing is included.

DATA SOURCES

The WHO and EORTC classification publications and the relevant recent literature were used to compile appropriate and practical guidelines in this review.

CONCLUSIONS

The practice of dermatopathology and hematopathology varies widely. Thus, while this review provides an overview and guideline for the workup of lymphoid lesions of the skin, the practitioner should understand the importance of clinical correlation as well as appropriate utility of available resources (such as clonality testing) in arriving at a diagnosis in cutaneous lymphoid lesions.

Early lymphoid lesions: conceptual, diagnostic and clinical challenges

There are no "benign lymphomas", a fact due to the nature of lymphoid cells to circulate and home as part of their normal function. Thus, benign clonal expansions of lymphocytes are only rarely recognized when localized. Recent studies have identified a number of lymphoid proliferations that lie at the interface between benign and malignant. Some of these are clonal proliferations that carry many of the molecular hallmarks of their malignant counterparts, such as BCL2/IGH and CCND1/IGH translocations associated with the in situ forms of follicular lymphoma and mantle cell lymphoma, respectively. There are other clonal B-cell proliferations with low risk of progression; these include the pediatric variants of follicular lymphoma and marginal zone lymphoma. Historically, early or incipient forms of T/NK-cell neoplasia also have been identified, such as lymphomatoid papulosis and refractory celiac disease. More recently an indolent form of T-cell lymphoproliferative disease affecting the gastrointestinal tract has been described. Usually, CD8(+), the clonal cells are confined to the mucosa. The clinical course is chronic, but non-progressive. NK-cell enteropathy is a clinically similar condition, composed of cytologically atypical NK-cells that may involve the stomach, small bowel or colon. Breast implant-associated anaplastic large cell lymphoma is a cytologically alarming lesion that is self-limited if confined to the seroma cavity. Atypical lymphoid proliferations that lie at the border of benign and malignant can serve as instructive models of lymphomagenesis. It is also critical that they be correctly diagnosed to avoid unnecessary and potentially harmful therapy.

Diagnostic and prognostic value of BCL2 rearrangement in 53 patients with follicular lymphoma presenting as primary skin lesions

OBJECTIVES

To study the diagnostic value of BCL2 rearrangement in follicle center lymphoma (FCL) presenting as primary skin lesions, evaluate its prevalence and the prognostic value in primary cutaneous FCL (PCFCL), and assess prognostic factors in PCFCL.

METHODS

Fifty-three patients with a cutaneous presentation of FCL without a history of nodal lymphoma were selected retrospectively. Clinical and histologic data were collected together with staging and follow-up data. A fluorescence in situ hybridization (FISH) test for BCL2 split probes was performed on skin biopsy specimens.

RESULTS

Initial staging procedures identified 47 PCFCLs and six cases of secondary skin involvement of FCL (SSIFCL). FISH detected seven cases carrying a BCL2 rearrangement: four (8.5%) of 47 PCFCLs and three (50%) of six SSIFCLs. These seven cases coexpressed BCL2 and CD10. In PCFCL, cutaneous relapse rate was 42.6%. A small/medium centrocytic cell population was associated with a higher probability of skin relapse in univariate (P = .008) and multivariate (P = .028) analysis, and BCL2 rearrangement detection was associated with secondary extracutaneous spreading (P = .05).

CONCLUSIONS

We observed that BCL2 rearrangement in PCFCL is rare, associated with initial positivity of staging (diagnostic value) or with secondary extracutaneous spreading (prognostic value). In selected cases with BCL2-CD10 coexpression, FISH testing could detect patients with poor outcome and require closer monitoring.

Primary cutaneous B-cell lymphomas: part I. Clinical features, diagnosis, and classification

Primary cutaneous B-cell lymphomas (PCBCLs) are defined as lymphomas with a B-cell phenotype that present in the skin without evidence of systemic or extracutaneous disease at initial presentation, after adequate staging. In non-Hodgkin lymphomas, the skin is the second most common site of extranodal involvement after the gastrointestinal tract. PCBCLs are histologically very similar to their nodal counterparts, and these histologic similarities can lead to confusion about both therapy and prognosis. This article will summarize the clinical, pathologic, and diagnostic features of the 3 main types of PCBCL: primary cutaneous follicle center lymphoma, primary cutaneous marginal zone lymphoma, and primary cutaneous diffuse large B-cell lymphoma, leg-type, and the appropriate evaluation and staging procedures for each of these entities.

Peripheral T-cell and NK-cell lymphomas and their mimics; taking a step forward - report on the lymphoma workshop of the XVIth meeting of the European Association for Haematopathology and the Society for Hematopathology

Mature T-cell and T/NK-cell neoplasms are both uncommon and heterogeneous, among the broad category of non-Hodgkin lymphomas. Owing to the lack of specific genetic alterations in the vast majority, most currently defined entities show overlapping morphological and immunophenotypic features, and therefore pose a challenge to the diagnostic pathologist. In the light of recent immunophenotypic, cytogenetic and molecular genetics advances in the field of T-cell and T/NK-cell lymphomas, the focus of the lymphoma workshop of the European Association for Haematopathology/Society for Hematopathology meeting in Lisbon, Portugal, in October 2012 was to refine existing diagnostic criteria and clarify the borders between overlapping entities. The panel reviewed over 200 submitted cases, which were grouped into five categories: (i) angioimmunoblastic T-cell lymphoma and T-follicular-helper-cell-associated lymphomas; (ii) CD30-positive T-cell lymphomas/lymphoproliferative diseases; (iii) extranodal T-cell and NK-cell neoplasms; (iv) EBV-associated T-cell/NK-cell lymphomas/lymphoproliferative diseases; and (v) peripheral T-cell lymphoma, not otherwise specified, post-transplant lymphoproliferative disorders, and mimics. This report summarizes the discussions and conclusions of the workshop, which question current diagnostic criteria and provide recommendations for refining existing classifications.