Cutaneous follicular lymphoid hyperplasia with monotypic plasma cells. A clinicopathologic study of 18 patients

Cutaneous Lymphoid Hyperplasia With T-Cell Clonality and Monotypic Plasma Cells Secondary to a Tick Bite: A Hidden Critter and the Power of Deeper Levels

Cutaneous lymphoid hyperplasia (CLH) is a benign reactive process with T-cell or B-cell lymphocytic infiltration in the skin, which can simulate cutaneous lymphomas both clinically and histologically. Various antigenic stimuli have been implicated in the development of CLH, including tick bites. Finding histologic evidence of such triggering factors, however, is often difficult. Moreover, the presence of clonality in CLH can potentially be interpreted as a neoplastic process, posing a further diagnostic challenge to dermatopathologists, if one is not aware of such peculiar phenomena. Herein, we describe a case of CLH secondary to a tick bite, featuring both T-cell clonality and monotypic plasma cells with lambda light chain restriction; the diagnostic clue being tick parts, which became evident on assessment of deeper levels. To the best of our knowledge, this is the first reported case of a tick-associated clonal CLH with simultaneous detection of monoclonal T cells and monotypic lambda light chain restriction, mimicking primary cutaneous CD4+ small/medium T-cell lymphoproliferative disorder and Borrelia-associated primary cutaneous marginal zone B-cell lymphoma, respectively.

Kappa and lambda immunohistochemistry and in situ hybridization in the evaluation of atypical cutaneous lymphoid infiltrates

BACKGROUND

Atypical cutaneous lymphoid infiltrates are challenging lesions in dermatopathology. We present a summary of the literature regarding kappa and lambda immunohistochemistry (IHC) and in situ hybridization (ISH) in the evaluation of atypical cutaneous or mucosal lymphoid infiltrates.

METHODS

Relevant articles from 1967 to 2018 in the English language were identified and summarized. In the absence of larger studies, case series of n ≥ 3 were included.

RESULTS

Sixty-three articles assessing kappa and lambda IHC and/or ISH were identified. Most focused on marginal zone lymphomas. Other lymphomas included follicle center lymphoma, diffuse large B-cell lymphoma, chronic lymphocytic leukemia/small lymphocytic lymphoma, mantle cell lymphoma, lymphoplasmacytic lymphoma, plasmablastic lymphoma, multiple myeloma, monoclonal gammopathy of undetermined significance, and polyneuropathy, organomegaly, endocrinopathy, monoclonal protein, skin changes (POEMS). Non-neoplastic lesions included reactive lymphoid hyperplasia, cutaneous plasmacytosis, connective tissue disease, IgG4-related disease, acrodermatitis chronic atrophicans, Zoon balanitis, dermatitides, and infiltrates around epithelial dysplasias/neoplasias.

CONCLUSION

Kappa and lambda IHC and ISH are useful tools in the evaluation of cutaneous B-cell lymphomas and plasma cell neoplasms. The literature supports that the detection of light-chain restriction by IHC and ISH is one of the most useful findings in the differential diagnosis of reactive lymphoid hyperplasia vs B-cell lymphoma with plasmacytic differentiation.

Navigating the cutaneous B-cell lymphomas: avoiding the rocky shoals

In recent years great progress has been made in understanding the classification of lymphomas. The integration of morphologic, clinical, immunophenotypic, and molecular features provides a rational basis for defining disease entities and has led to worldwide consensus. Hematopathologists and dermatopathologists have worked together to define those lymphomas that are present most commonly in the skin. Some cutaneous lymphomas have distinctive features and differ from their nodal counterparts. This is most evident in the delineation of primary cutaneous follicle center lymphoma and primary cutaneous marginal zone lymphoma. Both are very indolent, with low risk to spread beyond the skin. Primary cutaneous marginal zone lymphoma shows evidence of immunoglobulin class switching, as distinct from involvement by other extranodal marginal zone lymphomas of MALT type, which may involve the skin secondarily. Some have suggested that primary cutaneous marginal zone lymphoma may be considered a benign clonal expansion, probably driven by antigen. Many cutaneous lymphomas share biological and clinical features with their systemic counterparts. For example, primary cutaneous large B-cell lymphoma, leg type, exhibits a similar gene expression and molecular profile as diffuse large B-cell lymphoma of the activated B-cell type, especially for those cases arising in other extranodal sites. In addition, Epstein-Barr virus plays a role in many cutaneous lesions including mucocutaneous ulcer, plasmablastic lymphoma, and even some cases of marginal zone lymphoma. These EBV-driven conditions may present primarily in the skin, but also involve other mainly extranodal sites. Thus, it is evident that some cutaneous and systemic lymphomas are driven by common pathogenetic mechanisms, necessitating an integrated approach for the classification of lymphoma in all sites.

Primary Cutaneous B-cell Lymphomas

B-cell lymphomas represent approximately 20% to 25% of primary cutaneous lymphomas. Within this group, most cases (>99%) are encompassed by 3 diagnostic entities: primary cutaneous marginal zone lymphoma, primary cutaneous follicle center lymphoma, and primary cutaneous diffuse large B-cell lymphoma, leg type. In this article, the authors present clinical, histopathologic, immunophenotypic, and molecular features of each of these entities and briefly discuss the rarer intravascular large B-cell lymphoma.

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.

Approach to Cutaneous Lymphoid Infiltrates: When to Consider Lymphoma?

Cutaneous lymphoid infiltrates (CLIs) are common in routine dermatopathology. However, differentiating a reactive CLI from a malignant lymphocytic infiltrate is often a significant challenge since many inflammatory dermatoses can clinically and/or histopathologically mimic cutaneous lymphomas, coined pseudolymphomas. We conducted a literature review from 1966 to July 1, 2015, at PubMed.gov using the search terms: Cutaneous lymphoma, cutaneous pseudolymphoma, cutaneous lymphoid hyperplasia, simulants/mimics/imitators of cutaneous lymphomas, and cutaneous lymphoid infiltrates. The diagnostic approach to CLIs and the most common differential imitators of lymphoma is discussed herein based on six predominant morphologic and immunophenotypic, histopathologic patterns: (1) Superficial dermal T-cell infiltrates (2) superficial and deep dermal perivascular and/or nodular natural killer/T-cell infiltrates (3) pan-dermal diffuse T-cell infiltrates (4) panniculitic T-cell infiltrates (5) small cell predominant B-cell infiltrates, and (6) large-cell predominant B-cell infiltrates. Since no single histopathological feature is sufficient to discern between a benign and a malignant CLI, the overall balance of clinical, histopathological, immunophenotypic, and molecular features should be considered carefully to establish a diagnosis. Despite advances in ancillary studies such as immunohistochemistry and molecular clonality, these studies often display specificity and sensitivity limitations. Therefore, proper clinicopathological correlation still remains the gold standard for the precise diagnosis of CLIs.

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

The diagnosis and classification of the cutaneous B-cell lymphomas can be quite a challenge, with a definitive diagnosis sometimes being elusive, even when an extensive workup has been performed. Distinction of benign from neoplastic disorders can be difficult, with some hyperplasias mimicking lymphomas and vice versa. There are only a limited number of skin-specific B-cell lymphomas, including primary cutaneous follicle center lymphoma and primary cutaneous diffuse large B-cell lymphoma, leg type. Cutaneous marginal zone lymphomas have distinctive features but are classified with the other mucosa-associated lymphoid tissue lymphomas. It is important, however, to also remember that many other B-cell lymphomas/ plasma cell neoplasms can primarily, or more often secondarily, involve the skin. Some may mimic one of the skin-specific lymphomas but have very different clinical implications. Iatrogenic and senescent immunodeficiency-associated lymphoproliferative disorders that are often Epstein-Barr virus (EBV) positive can also primarily involve the skin, including cases also known as EBV-positive mucocutaneous ulcer.

Transformation of vulvar pseudolymphoma (lymphoma-like lesion) into a marginal zone B-cell lymphoma of labium majus

Lymphomas arising in the female genital tract are extremely uncommon. Diffuse large B-cell lymphoma and follicular lymphoma are the most common types. We describe the case of an 80-year-old woman with a recurrent lesion in the vulva initially diagnosed as a lymphoma-like lesion and evolving 7 years later into a marginal zone B-cell lymphoma (lymphoplasmacytic lymphoma). Diagnosis was based on the monotypic pattern of the plasmacellular component and the clonal rearrangement of immunoglobulin heavy chain genes. No previous cases of vulvar marginal zone B-cell lymphoma arising in the context of a persistent lymphoma-like lesion have been reported. We highlight the importance of differentiating benign from malignant lymphoid infiltrates in the vulva.

B-Cell Cutaneous Lymphoid Hyperplasia Representing Progressive Transformation of Germinal Center: A Report of 2 Cases

Cutaneous lymphoid hyperplasia (CLH) is a reactive polyclonal benign lymphoproliferative process predominantly composed of B cells or T cells, either localized or disseminated. The authors report histomorphologic, immunophenotypic, and genotypic findings of 2 cases of B-cell CLH demonstrating progressive transformation of germinal center (PTGC). Histologically, most of the lymphoid follicles were PTGCs with a few hyperplastic germinal centers. PTGC was characterized by enlarged but well-circumscribed follicles without clear demarcation of the germinal center and mantle zone, which contained a predominance of small lymphocytes and variable numbers of centrocytes, centroblasts, and immunoblasts. However, there were no centroblasts and immunoblasts resembling lymphocytic and/or histiocytic Reed—Sternberg cell variants in nodular lymphocyte—predominant Hodgkin lymphoma (NLPHL) in either lesion. These unusual CLHs should be differentiated from the primary cutaneous marginal zone B-cell lymphoma, primary cutaneous follicular lymphoma, particularly “floral variant,” or NLPHL. To avoid overdiagnosis and overtreatment, immunophenotypic and genotypic studies are required along with careful morphologic examination.

Borrelia burgdorferi-associated primary cutaneous marginal-zone B-cell lymphoma: a case report

An association between Borrelia burgdorferi with primary cutaneous B-cell lymphoma (PCBCL) has long been suspected but just recently, thanks to a polymerase chain reaction technique, it had been possible to demonstrate B. burgdorferi-specific DNA in skin lesions of patients with different PCBCL subtypes. Locating cases of PCBCL that are related to B. burgdorferi infection could be really important for therapeutic implications; in fact, there are several reports of PCBCL responding to antibiotic therapy against B. burgdorferi. We report a case of B. burgdorferi-associated primary cutaneous marginal-zone B-cell lymphoma that, after specific antimicrobial therapy, did not show any clinical regression. We can conclude that additional studies are necessary in order to establish the use of antimicrobial therapy in B. burgdorferi-associated PCBCL.

Study of the reactive dendritic cells in small B-cell lymphoproliferations of the skin

Distinguishing between low-grade primary cutaneous B-cell lymphoma (LG-pCBCL) and cutaneous lymphoid hyperplasia (CLH) based on histological features is often difficult. CLH lesions contain numerous reactive cells of the histiocyte lineage [Langerhans cells (LC), dermal dendritic cells (DDC), and macrophages], which are also often present in CBCL. The aim of this study was to determine whether immunohistochemical detection of those cells could help differentiate between CLH and LG-pCBCL. We determined the percentages of those histiocytic cells in the dermal infiltrates of 45 cases of cutaneous lymphoproliferations comprising 16 CLH and 29 LG-pCBCL (19 follicle-center cell lymphomas and 10 marginal zone lymphomas) by immunohistochemical labeling with antibodies to CD1a, FXIIIa, and CD68 to respectively detect LC, DDC, and macrophages. To avoid observer-dependent bias, an automated morphometric analysis method was used to recognize immunoreactive cells and calculate their percentages within the infiltrate. FXIIIa(+) cells were significatively more frequent in CLH than in LG-pCBCL, whereas CD1a(+) and CD68(+) cell frequencies were comparable in the two groups. The results of our study suggest that DDC might play an important role in the genesis of cutaneous lymphomas.

Aberrant nuclear BCL10 expression and lack of t(11;18)(q21;q21) in primary cutaneous marginal zone B-cell lymphoma

Inhibition of apoptosis seems to play an important role in the pathogenesis of marginal zone lymphoma. Apoptosis regulator B-cell lymphoma 10 (BCL10) may show aberrant nuclear localization in some aggressive extracutaneous MALT lymphomas, often in association with a MALT1 gene t(11;18)(q21;q21) translocation. The possible occurrence of this association in primary cutaneous marginal zone lymphoma (PCMZL) remains insufficiently explored. The aim of this study was to evaluate BCL10 protein expression pattern and its possible relationship to the presence of t(11;18)(q21;q21) and other MALT1 gene abnormalities in PCMZL and to assess their clinical significance. The study included 42 consecutive PCMZL patients diagnosed on the basis of the World Health Organization/European Organization for the Research and Treatment of Cancer classification criteria. BCL10 expression was immunohistochemically evaluated in all cases, whereas t(11;18)(q21;q21) reverse transcriptase polymerase chain reaction amplification was performed on 21 samples. In addition, the presence of other MALT1 gene translocations was explored in 26 samples by interphase fluorescence in situ hybridization using a MALT1 locus-specific probe. We observed the presence of aberrant nuclear BCL10 expression in a significant number of PCMZL cases (36%, 15/42). This aberrant expression was significantly related to the development of extracutaneous disease. In contrast, neither the t(11;18)(q21;q21) translocation nor other MALT1 gene translocations could be demonstrated. t(11;18)(q21;q21), strongly linked to extracutaneous MALT lymphomas, does not seem to play a role in PCMZL. The participation of other MALT1 gene translocations in PCMZL pathogenesis seems also unlikely.

Massive cutaneous follicular lymphoid hyperplasia in a patient with the Sjögren syndrome: 7-year follow-up and immunohistochemical study

The Sjögren syndrome often gives rise to complications such as pseudolymphomas and/or mucosa-/skin-associated lymphocytic tumors (MALT/SALT lymphomas). This paper presents a 74-year-old female patient with the Sjögren syndrome complicated by cutaneous plaques/tumors as cutaneous lymphoid hyperplasia over a 7-year follow-up study period. Immunohistochemical examination disclosed B-cell rich lymphoid follicle formation in the skin with the presence of T and B cells and a varied assortment of features to include abundant plasma cell infiltration. Based on the clinical course and histopathological findings, patient condition was considered benign and arises from reaction toward certain unknown microbes.

Clonal B cell populations in a minority of patients with Hashimoto's thyroiditis

BACKGROUND

Hashimoto's thyroiditis (HT) is a risk factor for thyroid lymphoma, and clonal B cell populations in HT support this link. The literature on B cell clonality in HT is controversial.

AIMS

To identify clonal B cell populations in HT and to assess their usefulness in differentiating HT from mucosa associated lymphoid tissue (MALT) lymphoma and predicting future development of lymphoma.

METHODS

DNA from formalin fixed, paraffin wax embedded blocks of thyroid specimens from 10 patients with HT and two thyroid MALT lymphomas was analysed for B cell clonality by seminested polymerase chain reaction (PCR) using FRIII/LJH and FRIII/VLJH primers to amplify the IgH gene VDJ region. In one case, PCR products were sequenced. Immunohistochemistry was performed by labelled streptavidin-biotin technique using antibodies to: CD45, CD45RO, CD3, CD20, and cytokeratin.

RESULTS

The histopathological and clinical findings were characteristic of HT. Clonal bands were seen in three and a polyclonal smear pattern was seen in seven cases. The clonal bands in HT were associated with a background smear, and could not be reproduced from other blocks from the same case or from deeper sections of the same block. The clonal bands in thyroid lymphomas were not associated with a background smear and were reproducible. None of the patients with clonal B cells has developed malignant lymphoma during a follow up of 10-13 years.

CONCLUSIONS

B cell clonal bands in HT have different features from those in lymphoma (non-pure and non-reproducible) and do not predict future development of lymphoma.

Pathology of Primary Cutaneous B-Cell Lymphomas: Diagnosis and Classification

The skin is the second most common extranodal site for non-Hodgkin's lymphomas. Therefore, hematologists, pathologists, and dermatologists need to be familiar with these lymphomas. Primary cutaneous B-cell lymphomas are less common than T-cell lymphomas but have received much attention in the past few years. Their typical clinical and pathologic features are becoming clear. However, there is still some disagreement in terminology and characteristics of these lymphomas between the World Heath Organization (WHO) classification and the European Organisation for Research and Treatment of Cancer (EORTC) proposal for primary cutaneous lymphomas. This review will focus on the features of primary cutaneous B-cell lymphomas, compare and contrast areas of discordance between the WHO and EORTC systems, and outline areas for further investigation.

Automated kappa and lambda light chain mRNA expression for the assessment of B-cell clonality in cutaneous B-cell infiltrates: its utility and diagnostic application

INTRODUCTION

Primary cutaneous B-cell lymphoma (1 degrees CBCL) accounts for 25% of all lymphomas. The difficulty in distinction of reactive from neoplastic B-cell infiltrates prompts the use of molecular diagnostic adjuncts. While T-cell clonality can be seen in various reactive states, clonal B-cell infiltrates are often neoplastic; standard assays employed include polymerase chain reaction (PCR) or Southern blot analysis to assess heavy chain rearrangement. We sought to assess the utility of kappa (kappa) and lambda (lambda) mRNA expression using the Ventana automated assay (Ventana Medical Systems, Tucson, AZ, USA) in the analysis of atypical cutaneous B-cell lymphoid infiltrates.

MATERIALS AND METHODS

Multiple 4 micro m sections of paraffin-embedded, formalin-fixed skin biopsies from 31 patients with CBCL were placed on silane-coated slides, deparaffinized, then digested in pepsin (5 mg/ml) for 30 min at 37 degrees C. Fluorescein-tagged oligoprobes and tissue mRNA were denatured at 80 degrees C for 5 min, hybridized for 2 h at 37 degrees C, and incubated with antifluorescein alkaline phosphatase conjugates. Detection of the probe target complex employed nitroblue tetrazolium and bromochloroindolyl phosphate conjugates with a nuclear fast red counterstain. A kappa : lambda ratio > 3 : 1 was held to represent kappa light chain restriction and a kappa : lambda ratio </= 1 : 1 to indicate lambda light chain restriction.

RESULTS

The diagnosis in each case was determined by careful integration of clinical, histologic, and phenotypic data. The diagnoses included: pseudolymphoma (PL), marginal zone lymphoma (MZL), 1 degrees CBCL of the trunk, scalp or leg, 2 degrees lymphoma, and plasma cell dyscrasia. All but one case of lymphoma were light chain restricted. All cases of PL were proven to be polyclonal by this methodology. In non-plasmacytic small cell lymphomas, only 5-10% of the infiltrate expressed kappa or lambda, with clonality established through the abnormal kappa : lambda ratio. Interpretations were most difficult in the 2 degrees small cell-dominant follicular center cell lymphomas and easiest in cases with significant plasmacytic differentiation (i.e. MZL, immunocytomas, or plasma cell dyscrasias).

CONCLUSION

The Ventana kappa/lambda assay is a reliable, quick, and inexpensive way to determine B-cell clonality in cutaneous lymphoid infiltrates in paraffin-embedded formalin-fixed tissue.

Lymphoma of the skin

This chapter describes the various ways in which the non-Hodgkin's lymphomas can involve the skin, how these diseases should be assessed, standard treatments available in 2002, and new directions in research. The goal of the session is to succinctly review recent developments in lymphoma classification and treatment as they apply to the unique aspects of lymphoma when manifest in the skin. In Section I, Dr. Eric Hsi reviews the special characteristics of the lymphomas seen when they proliferate in the skin and the application of the new World Health Organization classification system to the cutaneous lymphomas, emphasizing the unique challenges of recognizing and correctly classifying these diseases. He summarizes the evidence in favor of including the skin lymphomas in the overall lymphoma classification scheme and concludes with a practical description of the specific skin lymphoma entities. In Section II, Dr. Joseph Connors describes the current optimal treatment of the B-cell lymphomas when they present in or metastasize to the skin. Building on the classification scheme described by Dr. Hsi, Dr. Connors outlines a treatment approach based on current understanding of pathophysiology of these diseases and application of each of the effective modalities available for cutaneous lymphoma including radiation, chemotherapy, and immunotherapy. In Section III, Dr. Francine Foss concludes the session with a discussion of the different T-cell lymphomas that start in or spread to the skin concentrating on mycosis fungoides, cutaneous anaplastic large cell lymphoma and peripheral T-cell lymphoma. She includes comments on the newer anti-T-cell chemo- and immuno-therapeutics focusing on agents and techniques specific for cutaneous T-cell lymphomas.

Cutaneous marginal zone B-cell lymphoma: a case accompanied by massive plasmacytoid cells

A 36-year-old man presented with a red nodule on his left shoulder. Histologically, there were variously sized, irregularly shaped nests throughout the dermis partly extending into the subcutaneous tissue. Masses of centrocyte-like cells were situated in the center of the tumor nests and accompanied by adjacent secondary follicle structures. Partial follicular colonization was seen. Massive plasmacytoid cells were located in the papillary dermis and the periphery of the tumor nests. Immunohistochemically, these centrocyte-like cells were positive for CD19 and alkaline phosphatase, and negative for CD5 and CD10. Cytoplasm of the plasmacytoid cells was positive for IgG and lambda-light chain, and negative for IgM, IgA, and kappa-light chain. Monotypic immunoglobulin staining including light chain restriction was shown. Clonal immunoglobulin heavy chain gene rearrangement by Southern blot analysis was shown in the tumor tissue. Morphologic, immunohistochemical, and molecular studies revealed that this patient had a cutaneous marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue type. Electron beam (total 40 Gy) irradiation was applied. The tumor disappeared completely. Neither local recurrence or metastasis have appeared during 3 years of follow-up.

Cutaneous lymphomas and pseudolymphomas: newly described entities

This chapter summarizes some recently described cutaneous lymphomas and pseudolymphomas with regard to their clinicopathological presentation, biological behavior and classification place. Among cutaneous lymphomas, the group of cytotoxic lymphomas, angioimmunoblastic T-cell lymphoma, intravascular lymphoma, hydroa-like lymphoma, marginal zone lymphoma, spindle-cell B-cell lymphoma, and B-cell lymphoma with a dermatomal distribution are presented. In the context of pseudolymphomas, cutaneous follicular lymphoid hyperplasia with monotypic plasma cells, pleomorphic reactions in molluscum contagiosum, and CD30+ reactions to parapoxvirus are discussed.

Primary cutaneous marginal zone B-cell lymphoma: a clinical, histopathological, immunophenotypic and molecular genetic study of 22 cases

BACKGROUND

Primary cutaneous marginal zone B-cell lymphoma (MZCL) has recently been described. Differentiation from follicular centre cell lymphomas and lymphocytomas is often difficult due to insufficient experience and a lack of large series of patients.

OBJECTIVES

To characterize primary cutaneous MZCL better, we report clinical, histopathological, immunophenotypic and molecular genetics features in a series of 22 patients.

METHODS

All patients were treated and followed up at the same institution. Diagnosis of MZCL was based on the World Health Organization classification criteria. All samples were routinely tested with a wide panel of monoclonal antibodies. DNA was extracted from every sample following standard methods. IgH rearrangement and t(14;18)(q32;q21) studies were performed in all samples.

RESULTS

Twenty-two patients (20 men, two women; mean age 50 years, range 24-77) were included. The mean follow-up was 43 months. Seventy per cent of patients presented with characteristic skin lesions on the trunk or extremities, consisting of deep red to violaceous infiltrated plaques, nodules or tumours frequently surrounded by diffuse or annular erythema. Four patients presented with lesions on the head and neck area. Two patients had disseminated skin lesions. The main histopathological features were non-epidermotropic, dense lymphocytic infiltrates mainly distributed in a nodular pattern. Adnexal involvement was usually present, with eventual formation of lymphoepithelial complexes. Cytologically, the infiltrate was polymorphous with marginal zone B cells and B-monocytoid cells. Blastoid CD30+ cells were often observed. Colonized reactive germinal centres and lymphoplasmocytoid differentiation were frequently present. Neoplastic cells were CD20+, CD79a+, CD5- and CD10-. Monotypic expression of light chains was observed in 18 cases (13 kappa; five lambda). Clonal IgH rearrangements were detected in 14 cases. The bcl-2 mutation t(14;18)(q32;q21) was demonstrated in two cases. Most patients were treated with local radiotherapy. Complete response rate with this approach was 100%. Six patients (27%) had skin recurrences from 6 months to 8 years after first treatment. Five patients (23%) had extracutaneous involvement. Two of them had a large cell transformation and one died of lymphoma. Three of four patients with head and neck presentation developed extracutaneous disease.

CONCLUSIONS

MZCL appears to be a well recognizable entity, clinically, histologically and immunophenotypically. Although prognosis is generally good, the disease has potential for skin as well as extracutaneous recurrences. Large cell transformation and head and neck presentation may be associated with a worse prognosis.

Heavy multinodular cutaneous lymphoid infiltrates: clinicopathologic features and B-cell clonality

BACKGROUND

Criteria for distinguishing between cutaneous lymphoid hyperplasia (CLH) and low-grade B-cell lymphoma are not well defined. We examined the hypothesis that the presence of a clonal B-cell population in heavy multinodular lymphoid infiltrates correlates with clinical presentation and outcome.

METHODS

We identified 29 patients with skin lesions characterized histologically by a heavy dermal lymphocytic infiltrate with a multinodular architecture and extension into deep dermis and subcutaneous fat. Clonality was assessed immunophenotypically by light-chain restriction and also by analysis for IgH-gene rearrangement using PCR on DNA extracted from paraffin blocks.

RESULTS

Follow-up (mean 80 months; median 45 months) was obtained in all patients. Twenty-four patients (83%) presented with a solitary lesion: only four had solitary recurrences, and none developed multiple synchronous lesions or systemic B-cell lymphoma. However, 9/24 of these solitary lesions (38%) were clonal by light-chain restriction or IgH PCR; 5/29 patients (17%) presented with multiple recurrent lesions and continued to develop lesions during the period of follow-up; 3/5 patients (60%) with multiple lesions demonstrated a B-cell clone. No patient developed systemic B-cell lymphoma.

CONCLUSIONS

Heavy, multinodular cutaneous lymphoid infiltrates have an excellent prognosis. Multiple lesions at presentation are the best predictor of recurrent multiple lesions confined to the skin. The presence of a clonal B-cell population does not correlate with clinical presentation or histology, nor does it predict development of further lesions or systemic lymphoma.

Cyclin D1 as an aid in the diagnosis of mantle cell lymphoma in skin biopsies: a case report

Mantle cell lymphoma (MCL), an uncommon and aggressive form of non-Hodgkin lymphoma, typically involves lymph nodes. It usually only secondarily involves extranodal sites. We describe an unusual case of a MCL that presented and relapsed in the earlobes. Light microscopic findings were initially regarded as suggestive of small lymphocytic lymphoma, although subsequent analysis of fresh tissue by flow cytometry led to the diagnosis of MCL. Retrospective application of a broad panel of recently developed markers suitable for analysis of routinely processed tissue yielded results that also permitted a diagnosis of MCL. If these results had been available at the time of initial presentation, they would have obviated the need for rebiopsy. Greater awareness not only of the phenotypic criteria by which lymphomas are classified but of the lymphoma markers available for evaluation of routinely processed tissue should facilitate the accurate diagnosis of diseases like MCL and minimize the risk of misdiagnosis as an indolent disorder.

Reduced number of CD1a+ cells in cutaneous B-cell lymphoma

Cutaneous B-cell lymphoma is difficult to distinguish from pseudolymphoma. The histologic pattern and monoclonal restriction (immunohistochemical analysis and molecular biology) are the criteria used for differentiating these entities. CD1a+ dendritic cells have been observed in the infiltrates of T-cell lymphoma, but the presence of these CD1a+ cells has not been compared in B-cell lymphoma and pseudolymphoma. We studied the presence of CD1a+ cells on frozen sections of 23 B-cell lymphomas, 13 pseudolymphomas, and 17 T-cell lymphomas by immunohistochemical analysis. We found abundant CD1a+ dendritic cells in only 1 (4%) of 23 B-cell lymphomas, whereas in 8 (62%) of 13 pseudolymphomas and 17 (100%) of 17 T-cell lymphomas, strong CD1a staining was present. Our study demonstrates a distinct pattern of CD1a staining in the infiltrates of B-cell lymphoma and pseudolymphoma that may be of value in the differential diagnosis of these skin disorders.

Classification of cutaneous lymphoma: a critical appraisal of recent proposals

The classification of cutaneous lymphoma is a contentious issue. In this short review the merits of REAL classification and EORTC classification for cutaneous lymphoproliferative disease are examined. Points of terminological confusion between the two schemes are considered and a brief account of less common or ambiguous lymphoma types is provided.

Cutaneous lymphoid hyperplasia and cutaneous marginal zone lymphoma: comparison of morphologic and immunophenotypic features

Cutaneous marginal zone lymphoma (MZL) is a recently described low-grade B-cell lymphoma that usually follows an indolent course. This tumor shares many histologic and clinical features with cutaneous lymphoid hyperplasia (CLH), a benign reactive lymphoid proliferation. Sixteen biopsy specimens from 14 patients with CLH were studied, and compared with 16 cases of cutaneous MZL (9 primary cutaneous, 7 with secondary involvement of the skin) to determine whether there were features that would permit their distinction on routinely fixed, paraffin-embedded tissue sections. Both disorders showed a female preponderance (CLH: 9 F, 5 M; MZL: 11 F, 5 M). The median age was also similar (CLH: 54 years; cutaneous MZL: 55 years). CLH was most common on the arm (8) and the head and neck (7) but also involved the trunk (1); primary cutaneous MZL most often involved the limbs (3), trunk (3), and head and neck (3). Lymphoma did not develop in any of the 14 CLH patients (follow-up ranging from 9 to 246 months, mean 62 months). Six of 9 patients with primary cutaneous MZL and all 7 patients with secondary cutaneous MZL experienced relapses, most commonly isolated to skin or a subcutaneous site. On hematoxylin-eosin stained sections, a diffuse proliferation of marginal zone cells (p < 0.0001), zones of plasma cells (p = 0.01), the absence of epidermal change (p = 0.01), reactive germinal centers (p = 0.03), and a diffuse pattern of dermal or subcutaneous infiltration (p = 0.03) were more often seen in cutaneous MZL. A dense lymphocytic infiltrate, bottom-heavy or top-heavy growth pattern, eosinophils, and a grenz zone were seen equally often in both disorders. Dutcher bodies were observed only in cutaneous MZL. Immunoperoxidase stains on formalin-fixed paraffin-embedded tissue sections showed monotypic expression of immunoglobulin light chains by plasma cells in 11 of 16 MZL cases. By definition, no case with monotypic plasma cells was diagnosed as CLH. In CLH, T cells usually outnumbered B cells, and a B:T cell ratio > or = 3:1 was not observed in any case. By contrast, 40% of the MZL cases showed a B:T cell ratio > or = 3:1. No coexpression of CD20 and CD43 was seen in any case of either MZL or CLH. In summary, the clinical presentations of CLH and MZL are similar. In contrast to historical criteria for diagnosing cutaneous lymphoid infiltrates, the presence of reactive follicles favors a diagnosis of cutaneous B-cell lymphoma (CBCL). In addition, a bottom-heavy or top-heavy growth pattern is not a distinctive finding. Marginal zone cells and zones or sheets of plasma cells are strong morphologic indicators of marginal zone lymphoma. The diagnosis of CBCL can be supported in 40% of the cases by demonstrating a B:T cell ratio of > or = 3:1, and confirmed in 70% of the cases by demonstrating monotypic light chain expression of plasma cells on paraffin sections.

Primary cutaneous marginal zone B-cell lymphoma: a recently described entity of low-grade malignant cutaneous B-cell lymphoma

Recently a new classification of primary cutaneous B-cell lymphomas (PCBCLs) has been proposed by the European Organization for Research and Treatment of Cancer (EORTC)--Cutaneous Lymphoma Project Group. The marginal zone B-cell lymphomas (MZLs) were not included as a distinct entity because of insufficient experience and controversial opinions. We have studied 32 patients (M:F ratio 1.5:1; age range 25-93 years; mean age 49.6 years; median age 50 years) to determine the diagnostic criteria of primary cutaneous MZL and the relationship with other low-grade malignant PCBCLs. For comparison, three patients with immunocytoma were included in the study. Clinically, patients presented with solitary or clustered reddish or red-brown papules, nodules, and plaques, sometimes surrounded by an erythematous halo. Histopathologic sections showed nodular or diffuse infiltrates involving the dermis and subcutaneous fat. Cytomorphologically small to medium-sized cells with indented nuclei and abundant pale cytoplasm (marginal zone cells, centrocyte-like cells) predominated. In addition, scattered blasts, lymphoplasmacytoid cells, and plasma cells were observed below the epidermis and at the periphery of the infiltrates. Reactive germinal centers were present in 75% of the cases. The three cases of immunocytoma showed a more monomorphous pattern with predominance of lymphoplasmacytoid cells. The marginal zone cells showed a CD20+, CD79a+, CD5- and Bcl-2+ immunophenotype. They expressed immunoglobulin G in the majority of the cases. Staining with the monocytoid B cell-related antibody KiM1p gave positive results in all specimens with a typical intracytoplasmic granular pattern. A monoclonal distribution of immunoglobulin light chains was observed in marginal zone cells in 75% of the cases. Germinal centers, when present, were either polyclonal or negative for both kappa and lambda light chains. Monoclonal rearrangement of the JH gene was detected via polymerase chain reaction (PCR) in 18 of 26 investigated specimens. Analysis in 12 patients of the bcl-2/immunoglobulin heavy chain gene rearrangement using PCR yielded negative results. Lesions were treated by surgical excision followed in some patients by local radiotherapy. Systemic antibiotic therapy was administered to three patients, with good response in two. The prognosis is excellent. After a mean follow-up of 47.9 months (range 6-252; median 24) all patients are alive without signs of systemic lymphoma. Primary cutaneous MZL represents a distinct clinicopathologic subtype of low-grade malignant PCBCL.

The Revised European-American Classification of Lymphoid Neoplasms (REAL): a new perspective for the classification of cutaneous lymphomas

Differing classification schemes for malignant lymphomas have been used in Europe and the United States. Attempts to translate between the principle classifications have been unsuccessful and historically it has been difficult to arrive at an unified approach. In addition, many new lymphoma entities have been recognized in recent years that are not delineated in any of the existing classification schemes. To provide a unified international basis for clinical and investigative work in this field, in 1994 the International Lymphoma Study Group (ILSG) proposed a new classification termed Revised European-American Classification of Lymphoid Neoplasms (REAL). This review discusses the REAL classification, especially as it pertains to cutaneous lymphomas, and provides insight into the clinicopathologic features of lymphoproliferative disease involving the skin. The premise of the REAL classification is that a classification scheme should be based on the delineation of disease entities, utilizing pathologic, immunophenotypic, genetic, and clinical features. Therefore, if cutaneous involvement is an integral aspect of any lymphoma subtype, this clinical information is included in the definition of that neoplasm. We conclude that the principles of the REAL classification are applicable to cutaneous lymphomas, as well as lymphomas involving other anatomic sites.

Primary cutaneous immunocytoma: report of an unusual case with secondary spreading to the gastrointestinal tract

Cutaneous immunocytoma are low-grade B-cell lymphomas, which affect the skin either primarily or secondarily. Primary cutaneous immunocytomas usually present with one or a small number of lesions, mainly in the extremities. They generally remain confined to the skin. Histologically, there are polymorphous infiltrates of cells, in which the presence of monoclonal plasma cells is characteristic. We describe a case of cutaneous immunocytoma with secondary spread to the gastrointestinal tract.

Marginal zone lymphoma (low-grade B-cell lymphoma of mucosa-associated lymphoid tissue type) of skin and subcutaneous tissue: a study of 15 patients

Extranodal low-grade B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) type occurs in the gastrointestinal tract, salivary gland, thyroid, orbit, lung, and breast. We report 15 patients with MALT-type lymphomas involving skin and subcutaneous tissue. All patients had tumors with histologic features of low-grade B-cell lymphoma of MALT type, including marginal zone cells (15 of 15 cases), plasmacytic differentiation (10 of 15 cases), Dutcher bodies (three of 15 cases), and reactive germinal centers (10 of 15 cases). All expressed pan B-cell antigens and monotypic immunoglobulin. Seven patients (five women, two men) aged 29 to 86 years (median, 53 years) had primary MALT-type lymphoma of skin (6) or subcutaneous tissue (1). One patient had persistent disease, and four patients had relapses involving skin, subcutaneous tissue, breast, orbit, and lymph node. At last follow-up (11-121 months; median, 36 months), one patient was alive with disease, and six patients had no evidence of disease. Three patients (two women, one man) aged 36 to 67 years (median, 57 years) had concurrent MALT-type lymphoma involving both subcutaneous tissue and extracutaneous sites at primary diagnosis, including lung, breast, orbit, lymph node, and bone marrow. One patient responded to treatment but relapsed with lymphoma of the skin and breast. The other two patients had persistent disease despite treatment. One patient died of disease at 25 months, and, at last follow-up (7 and 46 months), two patients were alive with disease. Five patients (four women and one man) aged 29 to 72 years (median, 63 years) had secondary skin or subcutaneous involvement by MALT-type lymphoma with primary tumors of ocular adnexa (3) or parotid gland (2). All five patients had relapses, which involved skin or subcutaneous tissue, parotid gland, lacrimal gland, breast, and lymph node. At last follow-up (61-137 months), two patients were alive with disease and three were alive with no evidence of disease. Low-grade B-cell lymphomas of MALT type may arise in or secondarily involve the skin and subcutaneous tissue and have a tendency to affect middle-aged to older women. These tumors are characterized by multiple extranodal relapses and are associated with long patient survival. Patients with primary MALT-type lymphoma of skin or subcutaneous tissue without extracutaneous involvement at diagnosis were more likely to experience prolonged disease-free survival than patients with extracutaneous spread at presentation (p < 0.03).