Dual genotype in cutaneous T cell lymphoma: immunoglobulin gene rearrangement in clonal T cell malignancy

Primary Cutaneous B-Cell Lymphoma Complicated by Clonal T-Cell Populations: A Diagnostic Dilemma

ABSTRACT

Cutaneous lymphomas, both B-cell and T-cell, are not uncommonly seen in the skin, but those lymphomas exhibiting clonality for both B-cell and T-cell populations are scarce. Characterization of dual receptor rearrangement as primary composite lymphoma versus primary lymphoma with reactionary response is complex and often a challenge that goes unrecognized. In this study, we report a unique case of T-cell gene rearrangement positivity complicating the diagnosis of primary cutaneous low-grade B-cell lymphoma along with a review of reported cases containing dual receptor rearrangement to identify trends among final diagnostic decisions. As one might guess, for cutaneous lymphomas presenting with clonality for both T-cell and B-cell receptors, diagnosis can be difficult and confusing because the differential is broad. The literature suggests the majority of these cases may be cutaneous composite lymphomas. However, immunohistochemical, clinical, and histomorphologic features must all be assessed for an accurate diagnosis, which is critical for proper prognosis and therapy.

The Diagnosis, Staging, and Treatment Options for Mycosis Fungoides

Background

Cutaneous T-cell lymphoma (CTCL) represents a spectrum of diseases composed of malignant T lymphocytes. The most common type is mycosis fungoides (MF). An accurate diagnosis of early MF may be difficult because of the varied clinical and histologic expressions of the disease.

Methods

The authors review the epidemiology, possible risk factors, clinical manifestations, diagnostic techniques, staging, prognosis, and treatment options for MF.

Results

The varied and often nonspecific clinical and bistologic presentations of MF may delay diagnosis and staging, thus necessitating further studies such as immunophenotyping and T-cell receptor gene rearrangement analysis.

Conclusions

A multidisciplinary approach to the diagnosis, staging, and treatment of MF assists in optimizing outcomes from management of patients with this disease.

Primary Cutaneous Lymphoproliferative Disorders With Dual Lineage Rearrangement

We present a series of 15 cases of cutaneous lymphoma and pseudolymphoma with dual lineage rearrangement identified among approximately 1200 cases of cutaneous lymphoproliferative disorders assessed in our 4 institutions during the last 8 years in which the results of both T-cell receptor and immunoglobulin heavy chain rearrangement investigations were available. On the basis of the clinicopathologic information, the cases were retrospectively subdivided into 2 categories: (1) cases with definite features of cutaneous lymphoma or pseudolymphoma (n = 11) and (2) cases with unclassifiable disease (n = 4). The detection of dual genotype in the first group did not influence the final diagnosis; 7 cases represented cutaneous B-cell lymphomas, 3 pseudolymphomas, and 1 case lymphomatoid papulosis. The presence of monoclonal T-cell receptor-gene rearrangements in these cases may be explained either by monoclonal or oligoclonal expansion of exuberant T cells (or B cells in case of lymphomatoid papulosis) or by lineage infidelity. Three patients with unclassifiable disease had several clinical and histopathologic features in common. They were elderly, presented with solitary lesions, were in good general health and histopathologically demonstrated a dense multinodular infiltrate containing approximately an equal number of T and B cells and a high number of histiocytes forming granulomas, with prominent granulomatous features in 2 cases. B cells were either scattered with the infiltrate or formed collections vaguely resembling follicles; Reed-Sternberg-like cells were seen in 2 cases. B cells showed expression neither of immunoglobulin light chain. The T-cell component was represented mainly by small, well-differentiated lymphocytes or slightly pleomorphic cells, with some medium-sized convoluted cells. Epstein-Barr virus was not detected by polymerase chain reaction. The exact classification of these cases is unknown; they differ histopathologically from previously published cases of bigenotypic cutaneous lymphomas. They may merely represent a growth or reactive pattern, but, on the other hand, may be low-grade lymphomas. If so, they may be histopathologically related to cutaneous Hodgkin disease, T-cell/histiocyte-rich large B-cell lymphoma, or composite lymphomas. Further reports are needed to identify these lesions to clarify their nature and biologic potential.

Antibody repertoire development in fetal and neonatal piglets. XI. The thymic B-cell repertoire develops independently from that in blood and mesenteric lymph nodes

The origin and function of thymic B cells is currently unresolved. In the present study we compared V(H) gene repertoire diversification in >3500 cloned VDJs (from 11 animals at three time-points, using three to five animals per time-point) that were expressed with immunoglobulin (Ig)M, IgD, IgG, IgA and IgE in thymus, mesenteric lymph nodes (MLN) and peripheral blood B cells (PBB) of newborn piglets and 5-week-old isolator piglets maintained germfree (GF) or colonized with Escherichia coli. The results showed that the repertoire expressed with IgM, IgD, IgG and IgA in PBB and MLN remained polyclonal, undiversified and unselected in piglets maintained GF for 5 weeks, that age and colonization resulted in significant repertoire diversification of IgG and IgA in the MLN and of IgG in blood, that the thymic B-cell repertoire was polyclonal, unaffected by colonization and showed no clonal selection in any isotype, and that the thymic IgA and IgE repertoires were more diverse at birth than the repertoire of any isotype in MLN or PBB. IgD was seldom recovered from the PBB of newborn piglets or at any time-point in thymus, but was recovered in the MLN of all 11 animals examined. The IgD and IgM repertoires in all tissues remained polyclonal and unselected, although V(H) usage by IgD transcripts did not always parallel that of IgM in the same tissue. Therefore, isotype-switched B cells in the thymic medulla cannot be accounted for by immigration of B cells diversified by colonization of the gut, and thymic B cells undergo switch recombination and repertoire diversification before birth without clonal selection.

Update on erythrodermic cutaneous T-cell lymphoma: report of the International Society for Cutaneous Lymphomas

Two conferences were sponsored by the International Society for Cutaneous Lymphomas (ISCL) to gain consensus on definitions and terminology for clinical use in erythrodermic cutaneous T-cell lymphoma (E-CTCL). Three subsets of E-CTCL were defined: Sézary syndrome ("leukemic phase" E-CTCL), erythrodermic mycosis fungoides (secondary E-CTCL that develops in patients with mycosis fungoides), and E-CTCL, not otherwise defined. The hematologic criteria recommended for Sézary syndrome are intended to identify patients with a worse prognosis compared with the other E-CTCL subsets and consist of one or more of the following: (1) an absolute Sézary cell count of 1000 cells/mm3 or more; (2) a CD4/CD8 ratio of 10 or higher caused by an increase in circulating T cells and/or an aberrant loss or expression of pan-T cell markers by flow cytometry; (3) increased lymphocyte counts with evidence of a T-cell clone in the blood by the Southern blot or polymerase chain reaction technique; or (4) a chromosomally abnormal T-cell clone. For staging purposes, it is proposed that these criteria define the B2 blood rating and that the B2 rating be considered equivalent to nodal involvement.

Antibody repertoire development in fetal and neonatal piglets. II. Characterization of heavy chain complementarity-determining region 3 diversity in the developing fetus

Since the actual combinatorial diversity in the V(H) repertoire in fetal piglets represents <1% of the potential in mice and humans, we wondered whether 1) complementarity-determining region 3 (CDR3) diversity was also restricted; 2) CDR3 diversity changed with fetal age; and 3) to what extent CDR3 contributed to the preimmune VDJ repertoire. CDR3 spectratyping and sequence analyses of 213 CDR3s recovered from >30 fetal animals of different ages showed that >95% of VDJ diversity resulted from junctional diversity. Unlike sheep and cattle, somatic hypermutation does not contribute to the repertoire. These studies also revealed that 1) N region additions are as extensive in VDJ rearrangements recovered at 30 days as those in late term fetuses, suggesting that TdT is fully active at the onset of VDJ rearrangement; 2) nearly 90% of all rearrangement are in-frame until late gestation; 3) the oligoclonal CDR3 spectratype of 30-day fetal liver becomes polyclonal by 50 days, while this change occurs much later in spleen; 4) there is little evidence of individual variation in CDR3 spectratype or differences in spectratype among lymphoid tissues with the exception of the thymus; and 4) there is a tendency for usage of the most J(H) proximal D(H) segment (D(H)B) to decrease in older fetuses and for the longer D(H) segment to be trimmed to the same length as the shorter D(H) when used in CDR3. These findings suggest that in the fetal piglet, highly restricted combinatorial diversity and the lack of somatic mutation are compensated by early onset of TdT activity and other mechanisms that contribute to CDR3 junctional diversity.

T-cell receptor gene analysis in the diagnosis of Sézary syndrome

Diagnosing Sézary syndrome (SS) on clinicopathological grounds alone is far from straightforward, particularly in the early stages of the disease. Atypical lymphocytes may be seen in the peripheral blood of patients with reactive forms of erythroderma, so additional criteria are needed to establish the diagnosis of a T-cell leukemia/lymphoma. A wide variety of confirmatory tests have been proposed in the literature, but there has been no systematic attempt to compare the specificity and sensitivity of these different methods. Recent data indicate that T-cell receptor (TCR) gene analysis is the most useful test currently available and that methods based on polymerase chain reaction are more sensitive than Southern blot analysis. We propose that the diagnostic criteria for SS should include erythroderma, atypical circulating mononuclear cells, and evidence of a clonal T-cell population in the peripheral blood. Clonality can be established with certainty by cytogenetic or TCR gene analysis, but only the latter is sufficiently sensitive to be of value in routine diagnosis. Immunophenotypic data showing an expanded CD4(+)/CD7(-) population, an elevated CD4/CD8 ratio, or restricted V beta expression are not specific to T-cell malignancy and should not be used as a sole diagnostic criteria in SS. Entry criteria for future clinical studies will need to be more rigorous if meaningful comparisons are to be made between different treatment options.

Cutaneous T-cell Lymphoma

BACKGROUND: Cutaneous T-cell lymphoma (CTCL) represents a spectrum of diseases composed of malignant helper T lymphocytes. An accurate diagnosis of early CTCL is difficult because of the varied clinical and histologic expressions of the disease. METHODS: The authors review the epidemiology, possible risk factors, clinical manifestations, diagnostic techniques, staging, prognosis, and treatment options for CTCL. RESULTS: The varied and often nonspecific clinical and histologic presentations of CTCL may delay diagnosis and staging, thus necessitating further studies such as immunophenotyping, flow cytometry, and T-cell receptor gene rearrangement analysis. CONCLUSIONS: A multidisciplinary approach to the diagnosis, staging, and treatment of CTCL assists in optimizing outcomes from management of patients with this disease.

Analyses of T-cell receptor beta-chain genes by Southern blotting in known and suspected cutaneous T-cell lymphoma. A study of 67 samples from 32 patients

In this study we have investigated the configuration of the T-cell receptor (TCR) beta-chain genes in benign cutaneous conditions (n = 5) and known (n = 22) or suspected (n = 5) cutaneous T-cell lymphoma (CTCL). Sequential biopsies from skin, lymph node, blood and/or bone marrow were available in 12 cases of the 22 confirmed CTCL, and a total of 67 samples were analysed. In the benign conditions, clonal rearrangements of the TCR beta-chain genes were seen in neither skin nor blood samples. In contrast, in CTCL clonal rearrangements were detected in all skin samples from plaque or tumour lesions of mycosis fungoides. Clonal TCR rearrangements were also present in skin and blood samples from two patients with Sèzary's syndrome, and in skin and blood samples from three of five patients with clinically suspected CTCL. In 10 patients with large cell lymphomas, clonal rearrangements were detected in skin samples in half of the cases. In the remaining patients, clonal TCR rearrangements could not be detected in the skin, but only in the blood and/or bone marrow specimens. Results from the analyses of sequential biopsies showed identical patterns of rearrangement in 11 patients. In the remaining patient, the pattern of rearrangement differed between skin and lymph node. These data confirm and extend previous reports and indicate that analysis of TCR beta-chain genes by Southern blotting forms a useful supplement to other methods for the diagnosis of known and suspected CTCL. They also emphasize the importance of studying not only skin, but also extracutaneous sites.

Coexistent cutaneous T-cell lymphoma and B-cell chronic lymphocytic leukaemia

Three patients with cutaneous T-cell lymphoma (CTCL) are reported who had concurrent B-cell chronic lymphocytic leukaemia (B-CLL). The separate lineage and clonal nature of the individual lymphoid malignancies were confirmed by gene-rearrangement analysis. The chronology of the illnesses did not support the hypothesis that CTCL predisposes to the development of B-cell proliferative disorders. There was no clear association with immunosuppressive therapy, and HTLV-1 studies were negative in all patients. Consequently, we speculate that a lymphoid stem cell defect, which may lead to the development of either aberrant B- or T-cell clones, may be responsible for such cases of dual lymphoid neoplasia.

Photopheresis: a clinically relevant immunobiologic response modifier

Photopheresis, the process by which peripheral blood is exposed in an extracorporeal flow system to photoactivated 8-methoxypsoralen (8-MOP), is an effective new treatment for certain disorders caused by aberrant T lymphocytes. It has become a standard therapy for advanced cutaneous T cell lymphoma and shows promise in the treatment of four autoimmune disorders (pemphigus vulgaris, the progressive systemic sclerosis form of scleroderma, rheumatoid arthritis, systemic lupus erythematosus) and in reversal of immunologic rejection of transplanted organs. Positive immunologic alterations observed in patients with AIDS-related complex merit further investigation, and preliminary trials in the management of patients with multiple sclerosis, myasthenia gravis and autoimmune insulin-dependent diabetes mellitus have recently been initiated. The inability of the treatment to meaningfully alter the course of the B cell malignancy, chronic lymphocytic leukemia, suggests that B cell proliferations, at least those involving malignant cells, may be more resistant to this treatment. The mechanism of action of photopheresis is likely to be multifaceted, but at least in experimental systems appears to involve an immunization against the pathogenic T cells, in a highly specific manner. Photoactivated 8-MOP initiates a cascade of cellular events by forming covalent photoadducts with nuclear DNA, with cell surface molecules and possibly with other cytoplasmic components of the ultraviolet exposed leukocytes. For reasons not yet clear, exposure of populations of T cells containing expanding a clone(s) of pathogenic T cells to photoactivated 8-MOP alters these cells so that their reinfusion induces a therapeutically significant immunologic reaction that targets unirradiated T cells of the same pathogenic clone(s). It is suggested that the specificity of the induced immunologic reaction may result, in sequence, from the exquisitely titratable damage that 8-MOP inflicts upon cells of the pathogenic clone(s), the return of these cells to an immunocompetent individual, the removal of the photo-damaged cells from the blood by the reticuloendothelial system and the preferential induction of an immune response against cells of the pathologically expanded clone(s).

T-cell receptor gene rearrangement analysis: cutaneous T cell lymphoma, peripheral T cell lymphoma, and premalignant and benign cutaneous lymphoproliferative disorders

T-cell receptor gene rearrangement analysis is a useful technique to detect clonality and determine lineage of lymphoid neoplasms. We examined 103 patients with mycosis fungoides, Sézary syndrome, peripheral T cell lymphoma, potentially malignant lymphoproliferative disorders including pre-Sézary syndrome, large plaque parapsoriasis, lymphomatoid papulosis and follicular mucinosis, and various benign inflammatory infiltrates. A clonal rearrangement was detected in skin samples in 20 of 24 patients with mycosis fungoides and in peripheral blood samples in 19 of 21 patients with Sézary syndrome. A clonal population was also detected in seven of eight cases classified as peripheral T cell lymphoma. The potentially malignant dermatoses tended to have clonal rearrangement, with the exception of large plaque parapsoriasis, and further follow-up is needed to correlate clonality with the disease course. These studies demonstrate the value of molecular genetics as an adjunct to morphology in the examination of patients with cutaneous lymphoproliferative disease.

Analysis of beta, gamma, and delta T-cell receptor genes in mycosis fungoides and Sezary syndrome

The authors have analyzed the configuration of immunoglobulin (Ig) and beta, gamma and delta T-cell receptor (TCR) genes in DNA extracted from skin, lymph nodes, and peripheral blood mononuclear cells obtained from 41 patients with mycosis fungoides (MF), 14 patients with Sezary syndrome, and 13 patients with benign inflammatory dermatoses. No discrete rearranged bands (DRB) were detected in patients with inflammatory dermatoses. In tissue DNA from 19 patients with MF DRB were detected with beta and gamma, but not delta TCR probes. Only one patient with MF had a rearrangement of gamma and delta with germ line beta TCR genes. In 13 patients multiple biopsies were analyzed and DRB, when present, were identical in different lesions from individual patients. In three patients analysis of DNA from dermatopathic lymph nodes did not reveal DRB. Analysis of peripheral blood DNA from 24 patients revealed a discrete rearrangement of the gamma TCR gene in four patients and both beta and gamma genes in four additional patients. In MF DRB were detected more frequently with advancing stage of disease in tissues (P less than 0.01) but not in peripheral blood (P equals 0.36). Of 14 patients with Sezary syndrome, eight had DRB in peripheral blood DNA with both beta and gamma probes and in three of these patients identical DRB were also detected in DNA from skin biopsy samples. In contrast, DRB were not detected in the peripheral blood of the other six patients. In both MF and Sezary syndrome there was no restricted usage of particular V gamma genes. These results indicate that in MF (1) T-cell clones can be detected in skin biopsy specimens from the majority of patients with early stage disease, (2) gamma delta T-cell clones are only rarely found, and (3) TCR gene analysis can detect T-cell clones in the peripheral blood with a greater degree of specificity than conventional light microscopic study. In Sezary syndrome these studies also suggest that a subset of patients have a polyclonal population of circulating atypical lymphoid cells. In addition these patients appear to have a better prognosis than those with monoclonal disease.

Cutaneous lymphomas of phenotypically undetermined lineage: contribution of genotypic analysis

Genotypic analyses were performed in six primary cutaneous lymphomas whose lineage could not be assessed on the basis of histologic and phenotypic data. By immunophenotyping, these neoplasms expressed leukocyte common antigen and HLA-DR but did not show consistent immunostaining for B-cell or T-cell differentiation antigens. Expression of nonspecific histiocytic markers such as lysozyme and alpha 1-antitrypsin was found in three cases. By genotyping, three cases retained a germline configuration and immunoglobulin gene rearrangement was observed in one case, T-cell receptor gene rearrangement was found in one case, and both types of rearrangements in one case. Of the three patients in whom gene rearrangements were noted, two rapidly died and the other patient, with a dual genotype, is still alive 15 years after diagnosis. The three patients without gene rearrangements are alive and well after a mean follow-up of 2.5 years. It appears that cutaneous lymphomas with an uncertain phenotype include at least some cases of authentic B-cell or T-cell lymphomas. The germline configuration that we observed in cases with a chronic course remains difficult to explain. It may be related to a low malignancy form of histiocytic lymphoma, an atypical polyclonal hyperplasia, or even a low-grade lymphoma arising from a primitive cell without established commitment to either B- or T-cell lineage.

Gene rearrangement analysis in lymphoid neoplasia

Current uses for gene rearrangement analysis in clinical dermatology are listed in Table 3. This technique is useful for determining the existence of clonal populations within a background of polyclonal lymphoid cells; therefore, it is helpful in the diagnosis and staging of patients with CTCL and PTCL. Although dual genotypes do occur, this technique is usually capable of determining lineage in a clonal lymphoid infiltrate and elucidating and characterizing the etiopathogenesis of certain neoplasms. On the basis of this review of the literature and our own experience, we conclude that gene rearrangement analysis shows great promise for monitoring response to therapy and detecting progression or relapse in patients with CTCL and PTCL. With the recent technology of PCR, it is possible to amplify specific sequences of DNA, detect molecular alterations in individual malignant T cells, and even identify exogenous retroviral gene sequences in tissues of patients with CTCL. Although gene rearrangement analysis has supported or established the clonal nature of lymphomatoid papulosis, pre-Sézary syndrome, granulomatous slack skin syndrome, and follicular mucinosis, the clinical significance of these findings is not yet clear. In the case of primary cutaneous B-cell lymphoma and its benign counterpart, B-cell pseudolymphoma, further investigation will be needed to determine the clinical significance of clonal rearrangements.

Genotypic analyses of Richter's syndrome

The authors report the immunogenotype of two cases of Richter's syndrome. The immunoglobulin gene rearrangement pattern obtained on Southern Blot analysis was found in both cases to be the same in leukemic blood cells and in the tissue involved by the lymphoma. The beta chain and gamma chain T-cell receptor gene rearrangement pattern exhibited a germ-line configuration in the peripheral blood cells and in the lymph node in Case 2, whereas in Case 1 the lymph node had a gene rearrangement in the beta chain, as well as in the gamma chain T-cell receptor, and the leukemic cells from bone marrow were found to be in a germ-line configuration for T-cell receptors (beta and gamma chains).

Production of hydrogen peroxide by cutaneous T-cell lymphoma following photopheresis with psoralens and ultraviolet light

Treatment of peripheral blood mononuclear cells with 8-methoxypsoralen (8-MOP) and ultraviolet light, a procedure known as PUVA, has been found to be useful in the management of systemically disseminated cutaneous T-cell lymphoma (CTCL). In the present study we used a highly sensitive flow cytometric assay in conjunction with the hydroperoxide-sensitive dye 2',7'-dichlorofluorescein diacetate to measure intracellular hydrogen peroxide in normal lymphocytes and CTCL following PUVA treatment. Based on their laser light-scattering properties, lymphocytes were separated into three major subpopulations. We found that ultraviolet light alone caused an increase in the hydrogen peroxide content of each of the subpopulations, a response that was augmented when the cells were pretreated with 8-MOP (50 ng/ml). Cells from CTCL patients were more sensitive to the effects of 8-MOP than were normal lymphocytes. In both cell types, the production of hydrogen peroxide was found to be inhibitable by catalase. We noted an increase in hydrogen peroxide production following photopheresis; however, this was observed only 24 h after treatment. In addition, a further increase in hydrogen peroxide production was observed in lymphocytes isolated from peripheral blood that had been obtained from patients at 15 min after a second photopheresis treatment. Hydrogen peroxide is known to modulate the action of cytokines as well as the immunological responses of leukocytes. Our data suggest that the production of hydrogen peroxide by lymphocytes may be important in the action of PUVA in CTCL.

A clonal CD4-positive T-cell line established from the blood of a patient with Sézary syndrome

The reported inability to establish long-term T-cell lines from the blood of cutaneous T-cell lymphoma patients with circulating neoplastic T cells has hindered the development of an in vitro system to investigate Sézary syndrome. We have established a rapidly proliferating T-cell line from the peripheral blood of a patient with Sézary syndrome, which expresses a mature helper T-cell phenotype and contains cytogenetic abnormalities and T-cell receptor gene rearrangements identical to those in the patient's blood. The method of establishment and characteristics of this line are described.

Characterization of neoplastic and reactive cells in T-cell lymphomas with cytogenetic, surface marker, and DNA methods

Three patients with T-cell lymphoma were studied with a combined cytogenetic-immunological analysis (MAC) as well as by Southern blotting analysis. The MAC method, which allows simultaneous study of both chromosomes and immunophenotype of a mitotic cell, revealed that in each case the karyotypically abnormal and, therefore, neoplastic cells originated from different stages of T-cell maturation. In one case the abnormality was seen in cells expressing CD3 and CD10, in the second in cells expressing CD3 and CD8, and in the third case in cells expressing CD4 but not CD3. Mitoses were frequent also in non-neoplastic cells, but these mitoses were normal. Southern blotting analysis revealed TCR beta rearrangements in all patients. In addition, one patient displayed TCR gamma rearrangement, and one patient a rearrangement in the IgH joining region.