Primary cutaneous follicle center cell lymphomas and large B cell lymphomas of the leg descend from germinal center cells. A single cell polymerase chain reaction analysis

Cutaneous B-cell lymphomas: 2023 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

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, multiagent chemotherapy is rarely appropriate. In contrast, management of patients with PCDLBCL, LT is comparable to the management of patients with systemic DLBCL.

Follicular Lymphoma in the 5th Edition of the WHO-Classification of Haematolymphoid Neoplasms-Updated Classification and New Biological Data

The conceptual description of Follicular lymphoma (FL) in the 5th edition of the World Health Organization (WHO) classification of haematolymphoid tumors (WHO-HAEM5) has undergone significant revision. The vast majority of FL (85%) with a follicular growth pattern are composed of centrocytes and centroblasts, harbor the t(14;18)(q32;q21) translocation and are now termed classic FL (cFL). They are set apart from three related subtypes, FL with predominantly follicular growth pattern, FL with unusual cytological features (uFL) and follicular large B-cell lymphoma (FLBCL). In contrast to the revised 4th edition of the WHO classification of haematolymphoid tumors (WHO-HAEM4R), grading of cFL is no longer mandatory. FL with a predominantly diffuse growth pattern had been previously recognized in WHO-HAEM4R. It frequently occurs as a large tumor in the inguinal region and is associated with CD23 expression. An absence of the IGH::BCL2 fusion and frequent STAT6 mutations along with 1p36 deletion or TNFRSF14 mutation is typical. The newly introduced subtype of uFL includes two subsets that significantly diverge from cFL: one with "blastoid" and one with "large centrocyte" variant cytological features. uFL more frequently displays variant immunophenotypic and genotypic features. FLBCL is largely identical to WHO-HAEM4R FL grade 3B and renaming was done for reasons of consistency throughout the classification. In-situ follicular B-cell neoplasm, pediatric-type FL, duodenal-type FL and primary cutaneous follicle center lymphoma are categorized as discrete entities. In addition, novel findings concerning underlying biological mechanisms in the pathogenesis of early and systemic follicular lymphoma will be presented.

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.

Acquired N-Linked Glycosylation Motifs in B-Cell Receptors of Primary Cutaneous B-Cell Lymphoma and the Normal B-Cell Repertoire

Primary cutaneous follicle center lymphoma (PCFCL) is a rare mature B-cell lymphoma with an unknown etiology. PCFCL resembles follicular lymphoma (FL) by cytomorphologic and microarchitectural criteria. FL B cells are selected for N-linked glycosylation motifs in their B-cell receptors (BCRs) that are acquired during continuous somatic hypermutation. The stimulation of mannosylated BCR by lectins on the tumor microenvironment is therefore a candidate driver in FL pathogenesis. We investigated whether the same mechanism could play a role in PCFCL pathogenesis. Full-length functional variable, diversity, and joining gene sequences of 18 PCFCL and 8 primary cutaneous diffuse large B-cell lymphoma, leg-type were identified by unbiased Anchoring Reverse Transcription of Immunoglobulin Sequences and Amplification by Nested PCR and BCR reconstruction from RNA sequencing data. Low BCR variation demonstrated negligible ongoing somatic hypermutation in PCFCL and primary cutaneous diffuse large B-cell lymphoma, leg-type, and indicated that the PCFCL microarchitecture does not act as a functional germinal center. Similar to FL but in contrast to primary cutaneous diffuse large B-cell lymphoma, leg-type, BCR genes of 15 PCFCLs (83%) had acquired N-linked glycosylation motifs. These motifs were located at the BCR positions converted to N-linked glycosylation motifs in normal B-cell repertoires with low prevalence but mostly at different positions than those found in FL. The cutaneous localization of PCFCL might suggest a role for lectins from commensal skin bacteria in PCFCL lymphomagenesis.

Cutaneous B-cell lymphomas: 2019 update on diagnosis, risk stratification, and management

DISEASE OVERVIEW

Approximately one-fourth of 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 are based on histologic 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 histology remains the most important prognostic determinant. 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

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

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.

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 B-cell lymphomas: 2016 update on diagnosis, risk-stratification, and management

DISEASE OVERVIEW

Approximately one-fourth of 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 histologic 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 histology remains the most important prognostic determinant. 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

PCFCL and PCMZL patients with solitary or relatively few skin lesions may be affectively managed with local radiation therapy. While single-agent rituximab may be employed for patients with more widespread skin involvement, multiagent chemotherapy is rarely appropriate. In contrast, management of patients with PCDLBCL, LT is comparable to the management of patients with systemic DLBCL. Am. J. Hematol. 91:1052-1055, 2016. © 2016 Wiley Periodicals, Inc.

Primary Cutaneous B-Cell Lymphoma in Young Monozygotic Twins: A Case Report

Although familial aggregation of lymphoproliferative disorders has been described, heredity has not been implicated in the etiology of primary cutaneous B-cell lymphomas (PCBCL). We report herein the first case of 2 young monozygotic twins with PCBCL. The first twin was an 18-year-old woman when she presented with multiple skin nodules on the thorax and head. Histology showed an atypical small B-cell proliferation, consistent with primary cutaneous marginal zone lymphoma (PCMZL). Molecular genetics studies demonstrated B-cell clonality. Seven years later, the second twin developed her first lesion that was histologically similar to that of her twin. She subsequently developed other clinically similar lesions. Histology was consistent with PCMZL and showed B-cell clonality. Occurrence of PCBCL in these monozygotic twins raises the possibility of a genetic risk factor. Further study of such rare cases may offer valuable insights into the molecular basis of the etiology and pathogenesis of this unusual disorder.

Cutaneous B-cell lymphomas: 2015 update on diagnosis, risk-stratification, and management

DISEASE OVERVIEW

Approximately one-fourth of 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 histologic 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 histology remains the most important prognostic determinant. 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

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

Radiotherapy of primary cutaneous follicle center lymphoma: case report and review of literature

Primary cutaneous follicle center lymphoma is an indolent primary cutaneous B-cell lymphoma originating from the follicle center cells, composed of a combination of centrocytes (small and large cleaved cells) and centroblasts (large noncleaved cells) with a follicular, follicular/diffuse, or diffuse growth pattern. Lesions are mostly located on the head, neck and trunk. A case is presented of a 56-year-old male patient with primary cutaneous follicle center lymphoma, with lesions involving the skin of the back, shoulders, presternal area and right forearm. As the patient presented a disseminated cutaneous form of the disease that involved several anatomical regions, complete work-up was followed by superficial fractionated radiotherapy of eight fields in VI expositions, with total irradiation dose of 1400 cGy upon the following fields: right and left pectoral region, left and right shoulders, right suprascapular region, and proximal third of the right forearm. Total irradiation dose applied upon each field for the lesions located on the left and right side of the back was 1500 cGy. This therapy resulted in significant reduction of visible tumor. The patient was regularly followed up on outpatient basis for 12 months of radiotherapy, being free from local recurrence and systemic spread of the disease.

Cutaneous B-cell lymphomas: 2013 update on diagnosis, risk-stratification, and management

DISEASE OVERVIEW

Approximately one-fourth of 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 (PCLBCL, LT).

DIAGNOSIS

Diagnosis and disease classification is based on histologic 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 histology remains the most important prognostic determinant. Both PCFCL and PCMZL are indolent lymphomas that infrequently disseminate to extracutaneous sites and are associated with an excellent long-term prognosis. In contrast, PCLBCL, LT is an aggressive lymphoma with an inferior prognosis.

RISK-ADAPTED THERAPY

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

Primary cutaneous large B-cell lymphoma, leg type

Primary cutaneous large B-cell lymphoma, leg type, is a rare and aggressive neoplasm as defined by the recently updated World Health Organization-European Organization for Research and Treatment of Cancer classification of cutaneous lymphomas. We present a case of a 74-year-old woman who presented with a cutaneous lesion on her forearm. Skin biopsy revealed pathology consistent with this entity. The patient was treated with systemic chemotherapy with rituximab combined with doxorubicin, cyclophosphamide, vincristine, and prednisone. Here, we review the available literature and summarize clinical features and management of this uncommon subtype of non-Hodgkin lymphoma.

Immunocytochemistry and the diagnosis of cutaneous lymphoma

Cutaneous lymphoid infiltrates may pose some of the most difficult diagnostic problems in dermatopathology. Immunocytochemistry is often employed in an effort to determine whether an infiltrate is neoplastic or, in the case of clearly malignant infiltrates, to provide a specific diagnosis. The rarity of these disorders and the variant immunocytochemical profiles they may present further thwart understanding and sometimes prevent an accurate diagnosis. In this review the common immunocytochemical profiles of various cutaneous lymphomas are presented and potential pitfalls and problems considered. Immunocytochemistry is not a diagnostic test but, as in other areas of histopathology, is a highly valuable tool that requires critical interpretation within a context: so applied, it is an indispensable part of the pathologist's arsenal in evaluating lymphoid infiltrates and defining different lymphomas.

New prognostic relevant factors in primary cutaneous diffuse large B-cell lymphomas

BACKGROUND

There is a growing body of literature that has enhanced our understanding of the biology of primary cutaneous diffuse large B-cell lymphoma (PCDLBCL) including in the context of gene profiling studies. Recent studies have demonstrated an activated proliferation profile associated with leg type lymphoma including overexpression of proto-oncogenes PIM1, PIM2, and cMYC, and the transcription factors MUM1 and OCT2. Although gene profiling is very useful in understanding the molecular basis of diffuse large B-cell lymphoma (LBCL), it is not practical from a routine diagnostic perspective. In this regard, the purpose of the study was to further define an armamentarium of easily applied immunohistochemical stains to accurately prognosticate PCDLBCL.

METHODS

In all, 35 patients with PCDLBCL, 14 of follicle center and 21 of leg type, were analyzed using antibodies against CD5, CD138, BCL2, BCL6, OCT2, MUM1, FOXP1, and cMYC. Findings were correlated with clinical data.

RESULTS

All cases stained negative for CD5 and CD138. Both subtypes differed in distinct staining patterns for BCL6, BCL2, OCT2, MUM1, and FOXP1. Staining for BCL2, OCT2, and/or MUM1 was associated with poor, and BCL6 with a favorable prognosis. Expression of cMYC was irrespective of prognosis or subtype, whereas ulceration or primary manifestation on the leg or multiple lesions was indicative for worse prognosis.

LIMITATIONS

Case number was a limitation.

CONCLUSION

Discriminating PCDLBCL supports the validity of the World Health Organization/European Organization for Research and Treatment of Cancer classification. To identify risk factors in patients with PCDLBCL we recommend thorough evaluation of clinical presentation and exploratory staining pattern for BCL2, BCL6, MUM1 and OCT2.

New aspects in the biology of cutaneous B-cell lymphomas

Immunologic and molecular genetic studies greatly contributed to a better understanding and interpretation of the distinct clinico-pathologic features of primary cutaneous B-cell lymphomas (CBCL), which are the basis for the consensus WHO-EORTC classification. There is increasingly accumulating evidence that these well defined clinico-pathologic entities of CBCL have specific immunologic and molecular features, which further support their nosologic categorization as well as either interesting similarities with other extranodal B-cell lymphomas or definite peculiarities as compared to nodal B-cell lymphomas of similar histotype (specifically, follicle center lymphoma and diffuse large B-cell lymphoma).

Primary cutaneous B-cell lymphoma (marginal zone) with prominent T-cell component and aberrant dual (T and B) genotype; diagnostic usefulness of laser-capture microdissection

The presence of a dominant B- or T-cell clone is an important diagnostic criterion for distinguishing cutaneous lymphomas from lymphoid reactive infiltrates. Rarely, a combined B- and T-cell rearrangement can be detected from a single sample. In such instances, genotypic analysis does not permit differentiation of the coexistence of a T- and B-cell lymphoma from a single clone harbouring a monoclonal rearrangement for both immunoglobulin heavy chain and T-cell receptor genes. We herein report a case of a skin tumour consistent with a dense cutaneous lymphoid infiltrate showing a double prominent B- and T-cell component. A dual B- and T-cell clonality was detected by polymerase chain reaction from whole-tissue DNA sample. Genotypic analysis with DNA, obtained after laser-assisted microdissection from the B-cell population, again showed both T- and B-cell monoclonal rearrangements. Conversely, the microdissected T-cell population did not reveal a clonal pattern. The diagnosis of cutaneous B-cell lymphoma with a dual B- and T-cell genotype was established. This description illustrates the diagnostic usefulness of laser-capture microdissection in cutaneous lymphomas presenting dual genotype.

Neoplastic cells do not carry bcl2-JH rearrangements detected in a subset of primary cutaneous follicle center B-cell lymphomas

Whether primary cutaneous follicular lymphoma (PCFL) may or not represent a cutaneous equivalent to nodal follicular lymphoma (FL) is not determined. We have therefore investigated a series of PCFL to determine if tumoral cells carry or not the t(14;18)(q32;q21) translocation, a cytogenetic hallmark of nodal FL. Thirty cases of PFCL were selected according to the criteria of both the European Organisation for Research and Treatment of Cancer and the World Health Organization with 21 cases classified as grade 1 or 2 and 9 cases as grade 3. First, cutaneous tumors were studied by PCR for the amplification of bcl-2/JH rearrangements and by interphase fluorescence in situ hybridization using a dual color probe spanning t(14;18) breakpoints. Second, we tried to determine the origin of bcl2-JH-positive cells by a parallel bcl2-JH and immunoglobulin heavy chain gene amplification of blood mononuclear cells DNA and of DNA extracted from single microdissected B cells. Bcl2-JH rearrangements were amplified by PCR in skin of 9 of 30 (30%) patients with a similar-sized bcl2-JH rearrangement detected in the blood of 7 of these 9 cases. No t(14;18) breakpoint was detected by interphase fluorescence in situ hybridization analysis of 11 bcl2-JH-negative and 5 bcl2-JH-positive PCFL in contrast with its detection in the secondary cutaneous FL and in the nodal FL cases. Single-cell/multigene analysis showed that no single monoclonal B cells of PCFL carried the bcl2-JH rearrangement. Bystander or nontumoral t(14;18)+ B cells emigrating from blood may account for the detection of bcl2-JH rearrangements within PCFL material. Our study also underlines the diagnostic value of interphase fluorescence in situ hybridization to discriminate between t(14;18)-negative PCFL and extracutaneous FL involving the skin.

Diagnostic principles and new developments in primary cutaneous B-cell lymphomas

The most common subtypes of primary cutaneous B-cell lymphomas are marginal zone B-cell lymphoma/immunocytoma, follicle center cell lymphoma, and large B-cell lymphoma of the leg. Precise classification (European Organization for Research and Treatment of Cancer (EORTC) scheme) can be achieved only after a complete synthesis of clinical, histopathological, immunophenotypic, and molecular features. It is extremely important to emphasize that primary cutaneous B-cell lymphomas differ significantly from their nodal counterparts and are frequently characterized by an excellent prognosis. Awareness of this special clinical behavior should prevent the application of unnecessarily aggressive treatment protocols. Future definitions of primary cutaneous B-cell lymphomas will be based on their etiology and pathogenesis and especially on their molecular features. Some important areas are presented where exciting findings have been detected.

Bcl-2, Bcl-6 and CD10 expression in cutaneous B-cell lymphoma: further support for a follicle centre cell origin and differential diagnostic significance

BACKGROUND

Primary cutaneous follicle centre cell lymphomas (PCFCCLs) are the most common type of cutaneous B-cell lymphoma. There is ongoing discussion on the origin of the neoplastic B cells in these PCFCCLs, and consequently on their relation to the groups of primary cutaneous marginal zone B-cell lymphomas (PCMZLs) and nodal follicular lymphomas.

OBJECTIVES

To define better the neoplastic B cells in PCFCCLs, and to find out if differences in the expression of the antiapoptopic protein Bcl-2, and Bcl-6 and CD10, molecules which are normally expressed by the neoplastic B cells in nodal follicular lymphomas, might have diagnostic or prognostic significance in cutaneous B-cell lymphoproliferative disorders.

METHODS

Pretreatment biopsies of well-defined groups of PCFCCL (n = 24), PCMZL (n = 14), primary cutaneous large B-cell lymphoma of the leg (PCLBCL-leg; n = 19), secondary cutaneous follicular lymphoma (n = 3) and cutaneous pseudo-B-cell lymphoma (n = 6) were investigated by immunohistochemistry for expression of Bcl-2, Bcl-6 and CD10.

RESULTS

The PCFCCLs consistently expressed Bcl-6, whereas CD10 and Bcl-2 were expressed in only one and two of 24 cases, respectively. In contrast, PCMZLs were always negative for Bcl-6 and CD10, but were Bcl-2 positive, whereas skin and lymph node localizations of secondary cutaneous follicular lymphomas consistently expressed all of Bcl-2, Bcl-6 and CD10. Reactive follicle centre cells in pseudo-B-cell lymphomas expressed Bcl-6 (six of six cases) and CD10 (five of six cases), but not Bcl-2. PCLBCL-leg was Bcl-6 positive and CD10 negative in all cases, irrespective of clinical outcome, and strongly expressed Bcl-2 protein in all but two cases.

CONCLUSIONS

The results of the present study provide further support for the follicle centre cell origin of both PCFCCL and PCLBCL-leg, and indicate that staining for Bcl-2, Bcl-6 and CD10 can serve as an important adjunct in the differential diagnosis of cutaneous B-cell lymphoproliferative disorders.

Large B-cell lymphoma of the leg: clinical and pathologic characteristics in a North American series

BACKGROUND

Large B-cell lymphoma (LBCL) of the leg is an uncommon subset of primary cutaneous B-cell lymphoma that has been described in a series of European patients.

OBJECTIVE

Our purpose was to evaluate the clinical manifestation, diagnostic histopathology, immunophenotype, clinical course, and response to treatment of LBCL of the leg.

METHODS

We conducted a retrospective case series of 3 patients with primary LBCL of the leg.

RESULTS

The 3 elderly patients presented with progressive erythematous nodules on bilateral or unilateral lower extremities. All 3 patients had pre-existing peripheral edema or peripheral vascular disease. Histopathologic examination of the nodules showed dense lymphocytic infiltrates composed predominantly of large dysplastic lymphocytes that marked as B cells (CD20(+)). In 2 cases, the neoplastic cells were BCL-2 positive. All patients responded to initial therapy with localized electron beam radiation and chemotherapy but had disease progression. One patient had a complete and durable second response to anti-CD20 monoclonal antibody (rituximab).

CONCLUSIONS

The patients described have similar clinical and histopathologic features to those previously described. There may be an association between LBCL and pre-existing lower-extremity vascular disease. Treatment of LBCL is difficult, but 1 patient responded well to systemic anti-CD20 monoclonal antibody.

Gene expression profiles of cutaneous B cell lymphoma

We studied gene expression profiles of 17 cutaneous B cell lymphomas that were collected with 4-6 mm skin punch biopsies. We also included tissue from two cases of mycosis fungoides, three normal skin biopsies, and three tonsils to create a framework for further interpretation. A hierarchical cluster algorithm was applied for data analysis. Our results indicate that small amounts of skin tissue can be used successfully to perform microarray analysis and result in distinct gene expression patterns. Duplicate specimens clustered together demonstrating a reproducible technique. Within the cutaneous B cell lymphoma specimens two specific B cell differentiation stage signatures of germinal center B cells and plasma cells could be identified. Primary cutaneous follicular and primary cutaneous diffuse large B cell lymphomas had a germinal center B cell signature, whereas a subset of marginal zone lymphomas demonstrated a plasma cell signature. Primary and secondary follicular B cell lymphoma of the skin were closely related, despite previously reported genetic and phenotypic differences. In contrast primary and secondary cutaneous diffuse large B cell lymphoma were less related to each other. This pilot study allows a first glance into the complex and unique microenvironment of B cell lymphomas of the skin and provides a basis for future studies, which may lead to the identification of potential histologic and prognostic markers as well as therapeutic targets.