Clinicopathologic reassessment of primary cutaneous B-cell lymphomas with immunophenotypic and molecular genetic characterization

Clinicopathologic reassessment of non-mycosis fungoides primary cutaneous lymphomas during 17 years

BACKGROUND

New classification systems have recently been proposed for primary cutaneous lymphomas (PCLs). The aim of our study was to evaluate the applicability and significance of the new classification systems to the diagnosis and management of non-mycosis fungoides (non-MF) PCL.

METHODS

Immunohistochemical restaining, histological reclassification, and clinical follow-up of all new non-MF PCL cases during 17 consecutive years were performed. The histological reclassification was performed according to the Revised European-American Lymphoma (REAL) classification, except for lymphomatoid papulosis (Lyp), which was included as an indolent lymphoma, according to the European Organization for the Research and Treatment of Cancer (EORTC) classification.

RESULTS

During the period 1983-99, 251 new PCL cases were seen, 213 (85%) of which were MF and Sézary syndrome (eight cases), and 38 (15%) of which were non-MF. Of the latter, 20 (53%) were B-cell lymphomas, including eight (40%) follicle center lymphoma, follicular (FCLF), eight (40%) marginal zone lymphoma (MZL), two (10%) diffuse large cell lymphoma, and two (10%) unclassifiable cases. Most or all of the lesions did not stain for CD10, CD43, and bcl-2 protein, and immunostaining for kappa and lambda immunoglobulin light chain restriction was much more useful diagnostically in MZL. Of the 18 primary non-MF cutaneous T-cell lymphomas, 13 (72%) were Lyp, all of which were type A, four (22%) were CD30+ anaplastic large cell lymphoma, and one (6%) was natural killer (NK)/T-cell lymphoma. Except for the NK/T-cell lymphoma, all the other non-MF PCLs had an indolent course.

CONCLUSIONS

A minority of the routinely diagnosed PCLs are non-MF, equally divided between B- and T-cell lymphomas. The REAL classification is applicable to the majority, although it does not include entities such as Lyp; the clinical correlations are not as obvious because most of the non-MF PCLs tend to have a relatively indolent course.

The t(14;18) and bcl-2 expression are present in a subset of primary cutaneous follicular lymphoma: association with lower grade

According to the European Organization for Research and Treatment of Cancer classification, primary cutaneous follicle center cell lymphoma is not associated with the t(14;18)(q32;q21) and only rarely expresses bcl-2 protein. To further investigate this issue, we evaluated a series of 20 patients (14 men, 6 women) with primary cutaneous follicular lymphoma (PCFL). The presenting skin lesion was located in the head and neck region in 16 of 20 patients. Most cases were grade 2 (6/20) or grade 3 (13/20), and all had a follicular architecture. Immunohistochemical analysis demonstrated bcl-2 expression in 8 cases (40%), and expression was inversely related to the grade. Of 7 grade 1 or 2 cases, 5 (71%) were positive, whereas only 3 (23%) of 13 grade 3 cases were positive for bcl-2. Clonal immunoglobulin heavy chain gene rearrangements were detected in 9 (45%) of 20 cases. In 4 (20%) of 20 cases, we identified the major breakpoint of the t(14;18) by polymerase chain reaction, 3 of which were grade 1 or 2. We conclude that bcl-2 protein expression and the t(14;18) are present in a subset of PCFL, particularly in lower grade cases.

Detection of bcl-2/J(H) translocation by polymerase chain reaction: a summary of the experience of the Molecular Oncology Survey of the College of American Pathologist

CONTEXT

The t(14;18)(q32;;t6q21) translocation, found in about 85% of follicular lymphomas, brings the bcl-2 gene on 18q21 under control of the immunoglobulin heavy-chain gene transcriptional regulatory elements on 14q32. Detection of this translocation in a clinical sample suspected of containing lymphoma can assist the pathologist in diagnosis and classification of lymphoma. Polymerase chain reaction is a technology that is frequently used to detect the t(14;18)(q32;q21) translocation (bcl-2/J(H)). This article reviews the utility of polymerase chain reaction testing for bcl-2/J(H) detection and summarizes the experience of participants in the Molecular Oncology Proficiency Survey of the College of American Pathologists from 1997 through 2000.

OBJECTIVE

To describe current practice and encourage improvement of bcl-2/J(H) testing in clinical laboratories.

DESIGN

Retrospective analysis of Molecular Oncology Proficiency Survey data.

PARTICIPANTS

Laboratory participants in the College of American Pathology Molecular Oncology Proficiency Survey.

RESULTS

Twenty-four well-characterized specimens were sent to participants, of which 6 contained bcl-2/J(H) major breakpoint region translocations. Eight hundred nineteen major breakpoint region and 323 minor cluster region determinations were performed, with an overall correct response rate of 91% and 94%, respectively. No significant difference in correct response could be found for frozen versus paraffin-embedded tissues. Many laboratories did not know their assay sensitivity.

CONCLUSION

Overall performance was good; however, there was great variability in the methods reported and lack of knowledge of the limits of detection was common. Continued participation in external quality control programs, such as the Molecular Oncology Survey; dissemination of information that impacts on test performance; and technical recommendations from the molecular diagnostics community are critical for improved testing for bcl-2/J(H).

Primary cutaneous follicular lymphoma: a clinicopathologic and molecular study of 16 cases in support of a distinct entity

Primary cutaneous B-cell lymphomas displaying a prominent follicular growth pattern are rare and remain poorly defined, particularly in terms of the frequency of detection of t(14;18) and whether or not, as a group, they represent an entity distinct from follicular lymphoma arising in lymph nodes. The morphologic, immunophenotypic, and clinical features of 16 cases of primary cutaneous follicular lymphoma, identified during a review of all PCBCL in the Scotland and Newcastle Lymphoma Group database, were studied and the number of cases harboring t(14;18) assessed by polymerase chain reaction using primers to the major breakpoint cluster region. Comparisons were made with stage I follicular lymphoma arising in lymph nodes and follicular lymphoma secondarily involving the skin. All cases of primary cutaneous follicular lymphoma had undergone thorough staging, including physical examination and CT scans of chest and abdomen, with 15 of 16 cases also having bone marrow aspiration and/or trephine performed. The morphology and immunophenotype of the lesions were similar to that expected in lymph nodes. All cases displayed a follicular architecture complete with follicular dendritic cell networks and comprised an admixture of CD10 and/or bcl-6-positive neoplastic centrocytes and centroblasts with 13 of 16 cases also expressing bcl-2 protein. None harbored t(14;18), a significantly different finding compared with cases of stage I nodal follicular lymphoma (p <0.001) and secondary cutaneous follicular lymphoma (p <0.039). Relapses occurred in five of 15 patients with a median time to first relapse of 20 months (range 1-73 months; mean 27.2 months). These were multiple in two patients and involved extracutaneous sites in two patients. The propensity for relapse was similar to that in a comparative cohort of stage I nodal follicular lymphoma, but the group of primary cutaneous follicular lymphoma were significantly more likely to attain complete remission; all cases of primary cutaneous follicular lymphoma were in complete remission when last seen compared with 49 of 87 patients with stage I nodal follicular lymphoma (p <0.005). No lymphoma-related deaths were encountered in 15 cases with a mean follow-up >60 months (range 5-119 months). These results support the concept of a subtype of follicular lymphoma lacking t(14;18) involving the major breakpoint cluster region, and with a propensity to arise in the skin. Despite a high relapse rate patients with primary cutaneous follicular lymphoma are more likely to achieve complete remission and may ultimately have a more favorable long-term prognosis than those with equivalent nodal disease.

Primary subcutaneous follicular centre cell lymphoma with involvement of the galea: a case report and short review of the literature

Primary cutaneous follicular centre cell lymphoma (FCCL) is a distinct subtype of cutaneous lymphoma that originates from germinal centre cells. Histologically, the disease is typified by a bottom-heavy infiltrate with a diffuse or follicular growth pattern situated in the mid or deep dermis. In some cases, the neoplastic infiltrate may involve the underlying subcutaneous tissue, but so far primary subcutaneous FCCL has not been reported. We report the first case of primary FCCL located primarily in the deep subcutis with extension into the galea and review the literature on primary subcutaneous B-cell lymphomas.

Primary cutaneous diffuse large B-cell lymphoma: a clinicopathologic study of 15 cases

Primary cutaneous diffuse large B-cell lymphoma (DLBCL) is an uncommon lymphoma. Some authors have suggested that large B-cell lymphoma can be segregated based on anatomic site, with tumors of the lower extremity being unique. We report 15 cases of primary cutaneous DLBCL. Each case was analyzed immunohistochemically using antibodies specific for CD3, CD5, CD10, CD20, bcl-2, bcl-6, and p53. Polymerase chain reaction analysis for t(14;18)(q32;q21) also was performed. There were 13 men and 2 women (median age, 64 years). Thirteen tumors were composed predominantly of centroblasts, and 2 were immunoblastic. There was a median follow-up of 72 months. Of the 4 patients with primary cutaneous DLBCL of the lower extremity (thigh, knee, leg), 2 (50%) experienced a recurrence and 1 patient died of disease. In the non-lower extremity cases, 18% (2/11) recurred and no patients died of disease. We conclude that primary cutaneous DLBCL usually occurs in elderly patients with a male predominance. Recurrences are common, but death of disease is rare.

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.

Primary cutaneous follicular lymphoma: an assessment of clinical, histopathologic, immunophenotypic, and molecular features

PURPOSE

Unlike nodal follicular lymphoma (NFL), Primary cutaneous follicular lymphomas (PCFLs) rarely express Bcl-2 protein or t(14;18)(q32;q21) (Bcl-2/IgH). The aim of this study was to further characterize PCFL in a large series from North America.

PATIENTS AND METHODS

Clinical data and archival formalin-fixed, paraffin-embedded tissue were obtained from 32 patients. PCFL was defined as follicular lymphoma limited to the skin at the time of diagnosis and within the first 6 months after diagnosis. Specimens were analyzed for the expression of CD3, CD10, CD20, Bcl-2, and Bcl-6 proteins by immunohistochemistry as well as for the presence of t(14;18)(q32;q21) by polymerase chain reaction.

RESULTS

The male-to-female ratio was 1.5:1, with a median age of 60 years. Twenty-four patients had lesions on the head and neck, five had lesions on the trunk, and three had lesions on both head and trunk. Follow-up data were available in all cases, with a mean length of 35.8 months. The majority of the patients were treated with radiation therapy. All patients were alive at last follow-up except one. Recurrence was noted in seven patients (22%), after a mean disease-free survival time of 17.7 months. CD10 and Bcl-6 expression were seen in 29 (91%) of 32 and 31 (97%) of 32 cases, respectively. Bcl-2 expression was noted in 13 (41%) of 32 cases. PCR results for t(14;18)(q32;q21) were positive in 11 (34%) of 32 patients and showed correlation with Bcl-2 protein expression. The sequencing of the t(14;18)(q32;q21) amplicons confirmed unique breakpoints in each of the seven tested cases. Comparison between the Bcl-2 and/or t(14;18)(q32;q21)-positive and t(14;18)(q32;q21)-negative cases revealed no significant difference in age, site, clinical course, or outcome.

CONCLUSION

We demonstrated Bcl-2 protein expression and t(14;18)(q32;q21) in a significant minority of cases, suggesting a relationship with NFL. It remains to be seen whether, on longer follow-up, there is any clinical difference in cases with and without t(14;18)(q32;q21).

Cutaneous lymphomas: which pathological classification?

Cutaneous lymphomas are rare and although some are a manifestation of systemic lymphoma, the majority arise primarily from the skin. These primary cutaneous lymphomas comprise predominantly T cell subtypes and represent a wide spectrum of disorders. Pathologists can currently choose to label these conditions according to three classifications (REAL, EORTC or WHO) but each has shortcomings. Nonetheless, in an attempt to unify the field, we would recommend that pathologists make every attempt to categorise these conditions according to the WHO classification. This classification can encompass all the conditions and aligns the cutaneous lymphomas with the broader systemic lymphoproliferative conditions.

Angiotropic lymphoma: an immunophenotypically and clinically heterogeneous lymphoma

Angiotropic lymphoma (AL) is an uncommon lymphoma often presenting with nonspecific clinical features and having a high mortality rate. Although not specifically recognized by the Revised European-American Classification of Lymphoid Neoplasms, it likely will appear as a subtype of diffuse large B-cell lymphoma in the upcoming WHO classification. Some authors may also consider it to be a subtype of cutaneous lymphomas. Recent studies have reported an immunophenotypic heterogeneity of AL, and in rare instances, an association with other NHL. To further characterize AL, we studied the immunophenotype by immunohistochemistry for CD5, CD10, CD20, bcl-2, and bcl-6 in 18 cases of B-cell AL identified at three medical centers in North America. Bcl-2 gene rearrangement status by polymerase chain reaction and Epstein Barr virus status by in situ hybridization also were evaluated. Eight men and 10 women were identified with AL (median age 71 years). Eleven patients were diagnosed in life and seven were diagnosed at autopsy. Neurologic symptoms were the most common presentation, seen in six patients. Skin was the most commonly biopsied site. All showed classic intravascular localization; in two cases, there was also a minor diffuse large cell lymphoma component observed in some organs. Most (89%) of the cases expressed bcl-2 protein; CD10, bcl-6 and CD5 were each expressed in 22% of cases. Based on CD5 and CD10 expression, three major groups were evident: CD5-, CD10- (11 cases); CD5+, CD10- (3 cases), and CD5-, CD10+ (3 cases). Even though a follicle center lymphoma preceded the AL in one patient, we did not detect bcl-2 gene rearrangement in any of these cases. All cases were negative for Epstein Barr virus. Of the five treated with chemotherapy, two achieved a complete remission. Based on these findings, we conclude that ALs are clinically and immunophenotypically heterogeneous and may represent more than one pathogenetic entity. In some instances AL may be preceded by another lymphoproliferative disorder, raising the possibility that some cases of AL may represent a transformation from another type of lymphoma. Cutaneous manifestations of AL are common; however, it appears to be a systemic lymphoma. Although often fatal, patients with AL who are diagnosed early and treated with chemotherapy may achieve remission.

Follicular lymphoma of the salivary gland: a clinicopathological and molecular study of six cases

To clarify the clinicopathologic, immunohistologic, and genotypic features of follicular lymphoma arising from the salivary glands, we examined 20 cases of operatively resected primary salivary gland lymphoma and identified 6 such cases. There were 4 women and 2 men with ages ranging from 38 to 64 years (median 50 years). The tumor arose from the parotid gland in 4 cases and the submandibular gland in the remaining 2. Four patients were stage IE and 2 were stage IIE-1. The median follow-up period was 49 months and all patients were alive and well at the time of going to press. Histologically, 5 patients were follicular lymphoma grade 2, and 1 was grade 3. In all specimens in noninfiltrating salivary gland tissue, there was periductal lymphocytic infiltration near the lymphoma. Moreover, myoepithelial sialoadenitis was noted in 2 lesions. An immunohistochemical study revealed all 6 cases were CD10+, CD79a+, bcl-6+, CD3-, CD5-, CD21-, CD23-, and CyclinD1-. The tumor cells expressed bcl-2 in 3 cases and p53 oncoprotein in 4 cases. Two cases revealed clonal bands with polymerase chain reaction (PCR) assay for the immunoglobulin heavy (IgH) gene. The bcl-2/IgH translocation at the major breakpoint region was detected in 1 case (16%). We found a relatively high incidence of follicular lymphomas (30%) in salivary gland lymphomas. Among the mucosa-associated lymphoid tissue (MALT) system, follicular lymphomas appeared to occur frequently in the salivary glands as well as the duodenum and skin. Moreover, follicular lymphoma arising from the salivary glands appeared to have some of the characteristics of MALT-type lymphoma including indolent prognosis, presence of myoepithelial sialoadenitis, and rarity of the BCL-2 gene rearrangement.

Cutaneous follicle center lymphoma: a clinicopathologic study of 19 cases

Cutaneous follicle center lymphoma (FCL) is reported to have a unique immunophenotype and clinical course as compared with nodal FCL. We studied 19 cases of FCL of the skin using paraffin embedded tissue. An immunohistochemistry panel included CD45, CD3, CD20, CD43, CD21, bcl-2, bcl-6, CD5, and CD10. Molecular studies were performed by polymerase chain reaction for immunoglobulin heavy chain (IgH) and t(14;18). Trisomy 3 was performed by fluorescent in situ hybridization (FISH) in 13 cases. Follow up was obtained in 17 cases (range 3 to 137 months). Patients included 10 females and 9 males ranging in age from 33 to 88 years at first presentation (mean, 64). Twelve of 19 presented in the head and neck and 6 in the trunk and 1 on the arm. All had no known lymph node disease at presentation. Seventeen patients had no nodal disease with a minimum 3 month follow-up; 2/19 had unknown lymph node status with no follow-up. All cases were immunoreactive with CD20 and negative with CD3. Bcl-2 was immunoreactive in 11/18 cases, bcl-6 in 15/15, CD10 in 14/17, CD43 in 2/16 (both were CD10 immunoreactive) and CD5 in 1/15 (it was also bcl-6 immunoreactive). Eight of 18 cases were monoclonal for IgH. Three of 17 showed the presence of t(14;18). FISH was positive in 4 cases for trisomy 3 ranging from 16 to 22% (12% threshold). Follow-up showed no evidence of disease in 14/17 patients (4 to 137 mos). 3/17 patients are alive with disease (17 to 100 mo), and no patients died of disease.

Diffuse large cell lymphoma

A review of new or emerging ideas concerning diffuse large B-cell lymphomas is presented, with particular emphasis on histologic classification, genetic prognostic factors, first-line and salvage treatments, and specific locations such as neurologic, cutaneous, or gastrointestinal sites. This lymphoma remains the most heterogeneous of all lymphomas for its clinical characteristics and outcome. This heterogeneity is probably secondary to the fact that a large proportion of lymphomas seems to occur from a transformation of an unknown indolent lymphoma.

Primary cutaneous follicle center cell lymphoma

The exact classification of primary cutaneous follicle center cell lymphomas (FCCLs) has been the subject of ongoing debate. In the classification of cutaneous lymphomas proposed by the European Organization for Research and Treatment of Cancer (EORTC)-Cutaneous Lymphoma Project Group, cutaneous follicle center cell lymphoma (FCCL) is defined as a proliferation of centrocytes and centroblasts showing a diffuse pattern of growth in the great majority of cases, and presenting only rarely a true follicular pattern. CD10 and Bcl-2 are usually not expressed by neoplastic cells, and the t(14:18) is absent. By contrast, nodal follicular lymphoma is a tumor with a follicular pattern, characterized by the proliferation of CD10+, Bcl-2+ follicular cells, and by the presence of the t(14;18) in most cases. In this review we outline the clinicopathologic, phenotypic, and molecular features of primary cutaneous FCCL, reviewing criteria for diagnosis and differential diagnosis of this peculiar variant of cutaneous B-cell lymphoma.

Cutaneous presentation of follicular lymphomas

The description of primary cutaneous follicular lymphoma has raised interest in the differential diagnosis of this versus disseminated follicular lymphoma involving the skin. We report here on four cases of Stage IV follicular lymphoma, diagnosed in skin biopsy, in which cutaneous lesion was the most noticeable feature of clinical presentation. In all cases, the morphological features were superimposed over typical nodal follicular lymphoma. Apart from classic B-cell markers, they were characterized by CD10 and bcl6 positivity, markers of follicle germinal center cells; and bcl2 expression, with a corresponding t(14;18) translocation in three of three cases examined. In all four cases, bone marrow study and clinical staging revealed disease that had disseminated since diagnosis. Follow-up showed relapsing cutaneous and nodal disease in two cases. The only difference observed with a control group of 10 cases of primary cutaneous follicular lymphoma was the absence in this group of t(14; 18). Disseminated classical follicular lymphoma has to be considered in the differential diagnosis of follicular lymphoma presenting in the skin. This series of cases suggests that the presence of t(14;18) could imply the existence of disease that has disseminated beyond the skin and that cases harboring this translocation could be candidates for systemic polychemotherapy.

Spindle-cell B-cell lymphoma presenting in the skin

Lymphomas with predominant spindle-cell morphology have only been previously reported in small numbers; such lesions are potentially mistaken for sarcoma or other spindle-cell tumours. We describe a 73-year-old woman who presented with a tumour on the scalp of a few months' duration. Biopsy showed a B-cell lymphoma of follicle centre cell origin with a sarcomatoid appearance and a CD20+, CD10+, CD21+, bcl-6+ immunophenotype. This case highlights the very rare occurrence of spindle-cell B-cell lymphoma presenting in the skin. An awareness of this phenomenon is essential to avoid confusion with a variety of other cutaneous spindle-cell neoplasms and to enable a correct diagnosis to be made, thereby ensuring that appropriate treatment is initiated.

Lymphoma immunophenotyping: a new era in paraffin-section immunohistochemistry

Recent advances in immunohistochemistry have made it possible to investigate lymphomas for the expression of a wide range of antigens in fixed tissues. Epitope retrieval, sensitive detection methods, and the availability of new monoclonal antibodies have all contributed to one's ability to perform detailed immunophenotyping that previously could only be done in cryostat sections or by flow cytometry. Current lymphoma classifications make use of characteristic immunophenotypic profiles that aid in the reproducible diagnosis and subcassification of these neoplasms. The following is a review of the current state of immunophenotyping for lymphoid neoplasms in fixed tissues.

Cutaneous follicular B-cell lymphoma: description of a series of 18 cases

The lack of precise and homogeneous criteria for the recognition of primary cutaneous follicular lymphoma has hindered gaining data on the frequency and clinical and molecular features of this entity. In the course of a review of a series of primary cutaneous lymphoma from different Spanish hospitals, we collected a series of 18 cases of primary cutaneous follicular lymphoma and analyzed its clinical, morphologic, and biologic characteristics. In this review only cases with a follicular pattern of growth, germinal center cytology, and restriction to the skin in a minimum follow-up of 6 months have been included. Cases of primary cutaneous follicular lymphoma were characterized by the expression of classic markers of the germinal center, such as bcl6, CD10, and the presence of aggregates of follicular dendritic cells. They frequently express bcl2 protein, although classical t(14;18) was not found in any of the cases analyzed. Analysis of the bcl6 noncoding first exon showed somatic mutations in two of four cases analyzed, as would be expected in lymphoma deriving from the germinal center. Clinically, most cases showed initial involvement of the head and neck, with relapses in eight cases (involving the skin in five cases, both skin and lymph node in two cases, and lymph node in one case). No death attributable to the tumor was recorded. These data seem to imply that follicular lymphoma may present initially in the skin, lacking the characteristic t(14;18) and having a relatively indolent course. Recognition of these tumors and elucidation of their molecular alterations could lead to properly adapted staging and treatment protocols for these patients.

Cutaneous b-cell lymphomas of follicular and marginal zone types: use of Bcl-6, CD10, Bcl-2, and CD21 in differential diagnosis and classification

Cutaneous follicular lymphomas (FLs) and cutaneous B-cell lymphomas of extranodal marginal zone (MZL)/mucosal-associated lymphoid tissue (MALT) type may have morphologic overlap, despite the fact that they are thought to be of distinct derivation (germinal center vs. postgerminal center). The problem is compounded by the reported absence of bcl-2 expression by many cutaneous FLs, leading to speculation that cutaneous FL may be unrelated to nodal FL. The authors analyzed the expression of the germinal center-associated antigens bcl-6 and CD10 and of bcl-2 in 18 cutaneous B-cell lymphomas (10 FLs and eight MZLs), in relationship to CD21+ follicular structures, to clarify the relationship of nodal to cutaneous FLs and to explore the value of these antigens in differential diagnosis. The authors studied 10 cutaneous FLs (seven primary and three secondary) and eight MZLs (six primary and two secondary). The FLs (found in six men and four women age 45-75 years) involved the trunk (n = 3) and scalp, face and neck (n = 7). The MZLs (found in five women and three men age 34-81 years) involved the trunk (n = 4), face and neck (n = 2), and arm (n = 2). Immunostaining for CD21, bcl-6, CD10, and bcl-2 allowed the delineation of compartments within the tumors and yielded distinct patterns of staining in FL and MZL. In both follicular and interfollicular/diffuse areas of FL the neoplastic cells were bcl-6+ (10 of 10), often CD10+ (seven of 10, four of seven primary), and bcl-2+ (nine of 10, six of seven primary). Only three of seven cases (one of five primary) had bcl-2 rearrangement detectable by polymerase chain reaction. In the MZLs, the neoplastic B-cells were bcl-6-, CD10-, and bcl-2+ (eight of eight). Three patterns of CD21+ follicles were identified in MZL: reactive germinal centers, uniformly bcl-6+, CD10+, and bcl-2- (five of eight MZLs); colonized follicles, both bcl-6-, bcl-2+, and L26+ cells, and bcl-6+ and bcl-2- cells (five of eight MZLs); and expanded/colonized follicular dendritic cell meshworks, bcl-6- and bcl-2+ B cells with rare residual bcl-6+ and bcl-2- cells (four of eight MZLs). The authors conclude that cutaneous FLs express bcl-6 uniformly, usually express CD10 and bcl-2, and have a follicular pattern similar to nodal FL and consistent with a germinal center origin. The immunophenotype of cutaneous FL is distinct from that of cutaneous MZL, which is negative for bcl-6 and CD10. Colonized follicles in MZL, identified by CD21+ follicular dendritic cell meshworks, contained numerous bcl-6- and bcl-2+ B cells, and were readily distinguished from neoplastic follicles in FL. Conversely, CD21- interfollicular and diffuse areas in FLs contained bcl-6+ and CD10+ cells, which were not seen in diffuse areas of MZLs. Thus, the combination of bcl-2, bcl-6, and CD21 staining is useful for the distinction of cutaneous MZL from cutaneous FL.

Absence of the t(14;18) chromosomal translocation in primary cutaneous B-cell lymphoma

BACKGROUND

The t(14;18)(q32;q21) chromosomal translocation is found in the majority of nodal follicular lymphomas and in a lower percentage of systemic high-grade diffuse large B-cell lymphomas. The translocation results in the juxtaposition of the bcl-2 gene on chromosome 18 with the immunoglobulin heavy chain joining region on chromosome 14. Bcl-2 protein prevents apoptosis and the translocation leads to overexpression of a functionally normal Bcl-2 protein that prevents apoptosis of neoplastic cells.

OBJECTIVES

The purpose of our study was to analyse cases of primary cutaneous B-cell lymphoma (PCBCL) for the presence of the t(14;18) translocation and to correlate the results with Bcl-2 expression and histological subtype.

METHODS

Forty-four cutaneous B-cell lymphoid proliferations (36 PCBCL, four follicular B-cell lymphomas with cutaneous presentation and four reactive B-cell infiltrates) were analysed by polymerase chain reaction amplification and polyacrylamide gel electrophoresis using consensus primers for the joining region on the immunoglobulin heavy chain gene in combination with either a primer for the major breakpoint region (MBR) or the minor cluster region (mcr) on chromosome 18.

RESULTS

None of 36 PCBCL analysed demonstrated a t(14;18) translocation; however, three of four systemic follicular B-cell lymphomas presenting in the skin were found to have a translocation in the MBR, which was confirmed by sequence analysis. Correlation with Bcl-2 immunostaining showed that of seven patients with high-grade cutaneous diffuse large B-cell lymphoma, four were Bcl-2 positive but had no evidence of a t(14;18) translocation. In the five cases classified as primary cutaneous follicle centre cell lymphoma, the neoplastic cells within the germinal centres failed to express Bcl-2. However, Bcl-2-positive neoplastic cells were present in all four cases of systemic follicular lymphoma, including the case that did not show a t(14;18) translocation. In all cases of marginal zone lymphoma the marginal zone lymphocytes were Bcl-2 positive.

CONCLUSIONS

These findings indicate that the t(14;18) translocation does not occur in PCBCL, which suggests the involvement of different pathogenetic mechanisms compared with their nodal counterparts. Furthermore, the detection of a t(14;18) translocation in cutaneous B-cell lymphoma should suggest the presence of systemic disease, which underlies the need for exhaustive staging procedures.

Follicular lymphoma with marginal zone differentiation: microdissection demonstrates the t(14;18) in both the follicular and marginal zone components

On occasion, follicle center lymphomas (FCL) may contain a marginal-zone (MZ) component in which the interfollicular lymphoid cells take on an MZ cell morphology. In the past, these have been termed composite lymphomas. However, recent studies suggest that the two components are clonally related. It is unknown whether the bcl-2 translocation present in most FCLs is present in the cells that demonstrate MZ cell morphology. We have identified three cases of low-grade FCL with a MZ component suitable for laser capture microdissection (LCM) of the two components. Cases were immunophenotyped in paraffin section with antibodies to CD10, CD20, bcl-2, and bcl-6. LCM was done to isolate cells from each component. Polymerase chain reaction for t(14;18) using primers to the major breakpoint region was performed on DNA extracts. The sensitivity of the PCR assay was decreased to 5%--10% follicle center cells in a background of reactive tonsil cells. All three cases showed different phenotypes in each component. The FCL component was positive for all four of the above markers, whereas the MZ component expressed only CD20 and bcl-2. Both components showed t(14;18) amplicons of identical size, with the MZ component signal being stronger than the 5%--10% sensitivity control, suggesting that the signal was not from rare, contaminating FCL cells. These results confirm that both components are clonally related and support the theory that these are indeed FCLs with MZ differentiation (that retain the t(14;18)) rather than the reverse, MZ lymphoma with follicle center differentiation.

Primary cutaneous T-cell-rich B-cell lymphoma: clinically distinct from its nodal counterpart?

The cases of two patients with Stage IE primary cutaneous T-cell-rich B-cell lymphoma (TCRBCL) are described. In both, the lesion showed a dense infiltrate by numerous small T lymphocytes with scattered histiocytes and large atypical B-lymphoid cells. Polymerase chain reaction assays demonstrated that the B cells were monoclonal, with immunoglobulin heavy-chain gene rearrangement. No clonal rearrangements of the T-cell receptor gamma gene were observed. Both patients were disease-free at 4 months and at 5 years after therapy, respectively. Although rare, primary cutaneous T-cell-rich B-cell lymphoma appears to have a better prognosis than its nodal counterpart, with or without skin involvement.