Detection of TCR-gamma gene rearrangements in early mycosis fungoides by non-radioactive PCR-SSCP

Single-Cell RNA Sequencing Unveils the Clonal and Transcriptional Landscape of Cutaneous T-Cell Lymphomas

PURPOSE

Clonal malignant T lymphocytes constitute only a fraction of T cells in mycosis fungoides skin tumors and in the leukemic blood of Sézary syndrome, the classic types of cutaneous T-cell lymphomas. However, lack of markers specific for malignant lymphocytes prevents distinguishing them from benign T cells, thus delaying diagnosis and the development of targeted treatments. Here we applied single-cell methods to assess the transcriptional profiles of both malignant T-cell clones and reactive T lymphocytes directly in mycosis fungoides/Sézary syndrome patient samples.

EXPERIMENTAL DESIGN

Single-cell RNA sequencing was used to profile the T-cell immune repertoire simultaneously with gene expression in CD3+ lymphocytes from mycosis fungoides and healthy skin biopsies as well as from Sézary syndrome and control blood samples. Transcriptional data were validated in additional advanced-stage mycosis fungoides/Sézary syndrome skin and blood samples by immunofluorescence microscopy.

RESULTS

Several nonoverlapping clonotypes are expanded in the skin and blood of individual advanced-stage mycosis fungoides/Sézary syndrome patient samples, including a dominant malignant clone as well as additional minor malignant and reactive clones. While we detected upregulation of patient-specific as well as mycosis fungoides- and Sézary syndrome-specific oncogenic pathways within individual malignant clones, we also detected upregulation of several common pathways that included genes associated with cancer cell metabolism, cell-cycle regulation, de novo nucleotide biosynthesis, and invasion.

CONCLUSIONS

Our analysis unveils new insights into mycosis fungoides/Sézary syndrome pathogenesis by providing an unprecedented report of the transcriptional profile of malignant T-cell clones in the skin and blood of individual patients and offers novel prospective targets for personalized therapy.

Perplexing Rash: Challenges to Diagnosis and Management of Mycosis Fungoides

Mycosis fungoides is the most ubiquitous form of cutaneous T-cell lymphoma. Diagnosis is arduous, as early phases often resemble common inflammatory dermatoses. The principal histologic features of MF include medium to large-sized cerebriform mononuclear cells in single or small clusters in the epidermis. Treatment modalities are prodigious and relapses are common. The authors present a case of a 69-year-old man with mycosis fungoides, followed by a review of diagnostic modalities and phototherapeutic interventions for patients with this condition. According to literature reports, monochromatic excimer light therapy is the most advantageous and well-tolerated phototherapy modality for patients with early patch stage mycosis fungoides.

Duration of symptoms does not correlate with results of T-cell gene rearrangement studies in patients evaluated for cutaneous T-cell lymphoma

OBJECTIVES

We aimed to determine if clonality on T-cell gene rearrangement studies correlated with duration of cutaneous symptoms in patients with skin disease who are being evaluated for cutaneous T-cell lymphoma (CTCL). Specifically, our goal was to determine if symptom duration could help better optimize sample selection for T-cell gene rearrangement studies.

METHODS

Biopsies were reviewed from patients within both general dermatology clinic and CTCL specialty clinic for clonality results in relation to disease duration.

RESULTS

We did not find an association between duration and clonality in any group.

CONCLUSIONS

The yield of T-cell gene rearrangement studies is similar between shorter and longer duration of disease implying that there is not an optimal duration range in which T-cell gene rearrangement studies are more likely to give a positive result.

The role of immunohistochemical analysis in the diagnosis of parapsoriasis

Parapsoriasis is a chronic dermatosis whose biological distinction from early mycosis fungoides, the most frequent form of cutaneous T-cell lymphoma, is still not clearly defined. Two types of parapsoriasis have been delineated: large-plaque parapsoriasis and small-plaque parapsoriasis. The lack of clinical and histological features, which may allow distinguishing parapsoriasis from early mycosis fungoides has prompted several investigations to assess the role of immunohistochemistry in establishing a conclusive diagnosis of these conditions. However, the additional data obtained by immunohistochemical analysis concerning the CD4/CD8 ratio, the aberrant expression of T-cell antigens and the expression of proliferation markers has not generally helped establish a more definitive diagnosis. This review critically discusses these immunohistochemical markers and their use in diagnosis of parapsoriasis.

TCRgamma-chain gene rearrangement by PCR-based GeneScan: diagnostic accuracy improvement and clonal heterogeneity analysis in multiple cutaneous T-cell lymphoma samples

Cutaneous T-cell lymphomas are a heterogeneous group of lymphomas where the tumor population emerges within a multiple subclone pattern ("clonal heterogeneity"). PCR analysis has been shown to be useful in the diagnosis of mycosis fungoides (MF) and Sézary Syndrome (SS). Focusing the attention on clonal heterogeneity, the efficacy of the multiplex/heteroduplex (HD) PCR and the GeneScan (GS) capillary electrophoresis analysis was compared in the early diagnosis of MF/SS, using a multiple sample approach. Indeed, GS demonstrated TCRgamma gene rearrangement (GR) in all the 57 SS (100%) and in 123/146 (84%) of the MF samples, whereas the multiplex/HD PCR was less sensitive. An increase in clonality was observed in connection with both a worsening of the cutaneous disease (79% T1/T2; 100% T3/T4) and an increase in the histopathological score (HS < 5, 76%; HS > or = 5, 94%). Clonal heterogeneity with adjunctive reproducible skin TCRgamma-GRs was also observed. "Clonal instability," with different GRs, was present in a small percentage of patients. Therefore, it can be concluded that GS analysis in TCRgamma-GR is able to improve diagnosis in MF/SS patients and the multiple sample approach is helpful for a correct interpretation of clonal patterns in skin lesions, especially in early-stage MF and in SS skin/blood samples.

Histopathologic-molecular correlation in early mycosis fungoides using T-cell receptor gamma gene rearrangement by polymerase chain reaction with laser capture microdissection

BACKGROUND/PURPOSE

Early mycosis fungoides (MF) is difficult to distinguish from other benign inflammatory dermatoses. We evaluated clonal T-cell receptor (TCR) gamma gene rearrangement by polymerase chain reaction (PCR) as a surrogate to histologic diagnosis in early MF.

METHODS

Twenty paraffin-embedded skin biopsies from nine patients diagnosed with MF were included. Two multiplex PCR encompassing various Vgamma and Jgamma regions were used to detect TCRgamma gene rearrangements. Histologic diagnoses were categorized as "diagnostic", "consistent", "suggestive", or "nondiagnostic". We compared TCRgamma PCR results with histologic parameters to determine the differences between PCR-positive and PCR-negative groups.

RESULTS

TCRgamma PCR was positive in 53% (8/15) of the patch stage, in 100% (2/2) of the plaque stage, and in 100% (3/3) of the tumor stage. TCRgamma PCR was positive in 50% (4/8) of the specimens in both the diagnostic and consistent of MF groups, 71% (5/7) in the suggestive of MF group. We found that inflammation was more severe in PCR-negative specimens. Papillary dermal fibrosis was common, and differed significantly between PCR-positive and PCR-negative groups (p = 0.01). T-cell monoclonality was detected in one nondiagnostic lesion in a patient with psoriasis and MF.

CONCLUSION

TCRgamma PCR allows the diagnosis of MF in patients with lymphocyte-poor lesions, suggestive of MF pathologically. TCRgamma PCR is more likely to be negative with moderate to severe inflammation, particularly with papillary dermal fibrosis. We suggest that the ratio of malignant clonal to reactive T-cells is critical for MF diagnosis.

Mycosis fungoides ? a review of the management of 28 patients and of the recent literature

BACKGROUND

Mycosis fungoides is an uncommon cutaneous T-cell lymphoma characterized by malignant monoclonal proliferation of T-helper lymphocytes. Its course is variable with a potential for lymphatic and hematogenous involvement. We report the investigations, staging, treatment, follow-up, and outcome of 28 patients. This is the first such study reported from Ireland.

METHODS

Twenty-eight patients with mycosis fungoides (14 women, 14 men; average age, 52.5 years) were reviewed over 12 years in the dermatology clinic which assesses an average of 4500 patients per year. All mycosis fungoides patients were referred from their family physicians. The diagnosis was made in all cases from a combination of clinical findings, histology, and immunohistochemistry. TNM staging revealed 11 patients at diagnosis stage IA (T1), 12 at stage IB (T2), four at stage IIB (T3), and one at stage III (T4).

RESULTS

The usual male preponderance was not found. Eight patients needed multiple biopsies to establish the diagnosis. Detailed investigations were not useful in the early stages. Patients were followed up over a 12-year period. Thirteen patients died as a result of cutaneous lymphoma. Two patients with stage IA disease progressed rapidly and died, a feature reported in only 10% of patients at this stage. Five patients showed unusual features, including a long history prior to presentation, the development of the rarely reported bullous mycosis fungoides, and aggressive disease beginning at a young age.

CONCLUSIONS

Mycosis fungoides is rare; we reviewed 28 patients over 12 years. The prognosis is poor at the later stages; 13 patients died. Two patients who died were unusual in that they rapidly progressed from stage IA disease; however, in the majority of patients with this stage, the prognosis is excellent. Detailed investigations were unhelpful in early stage disease. Close clinical follow-up is essential to identify disease progression.

Defining early mycosis fungoides

This editorial review summarizes the results of 5 meetings sponsored by the International Society for Cutaneous Lymphoma at which the clinicopathologic and ancillary features of early mycosis fungoides were critically examined. Based on this analysis, an algorithm was developed for the diagnosis of early mycosis fungoides involving a holistic integration of clinical, histopathologic, immunopathologic, and molecular biological characteristics. A novel aspect of this algorithm is that it relies on multiple types of criteria rather than just one, for example, histopathology. Before its finalization, the proposed diagnostic algorithm will require validation and possibly further refinement at multiple centers during the next several years. It is anticipated that a more standardized approach to the diagnosis of early mycosis fungoides will have a beneficial impact on the epidemiology, prognostication, treatment, and analysis of clinical trials pertaining to this most common type of cutaneous lymphoma.

T-cell receptor γ gene rearrangement by multiplex polymerase chain reaction/heteroduplex analysis in patients with cutaneous T-cell lymphoma (mycosis fungoides/Sézary syndrome) and benign inflammatory disease: correlation with clinical, histological and i

BACKGROUND

A dominant T-cell clone can be detected by polymerase chain reaction (PCR) in 40-90% of cutaneous samples from patients with cutaneous T-cell lymphoma (CTCL).

MATERIALS AND METHODS

From 1996 to 2003 we analysed 547 cutaneous biopsies performed to exclude CTCL (mycosis fungoides, MF/Sézary syndrome, SS). The final diagnosis was benign inflammatory disease (BID) in 353 samples (64.5%) and CTCL in 194 (35.5%). T-cell receptor (TCR)-gamma gene rearrangement was studied by using a multiplex PCR/heteroduplex (HD) analysis. The PCR results were correlated with the clinical picture, the histological pattern and the presence of T-cell lineage antigen loss, using univariate and multivariate logistic regression analyses.

OBJECTIVE

To determine the sensitivity and specificity of the multiplex PCR/HD analysis and to identify which are the clinical, histopathological or immunophenotypical features significantly associated with a positive T-cell clonality.

RESULTS

A clonality was demonstrated in 83.5% of CTCL and in 2.3% of BID (P < 0.001). A significantly higher percentage of clonal cases was associated with the cutaneous T-score (71.4% in T1, 76.1% in T2 and 100% in nodular and erythrodermic MF samples) and with the presence of a T-cell lineage antigen loss (93.9% vs. 77.4%). Moreover, clonality was closely related to an increase in the histopathological score (51.3% in the samples with a score < 5, compared with 92% in the lesions with > or = 5). No significant difference in the percentage of clonal cases was found between T1/T2 and T3/T4 lesions with a histopathological score > or = 5. The multivariate logistic regression showed that the density and extent of the cell infiltrate, the degree of epidermotropism and the presence of cytological atypia share an independent predictive value for clonality in T1/T2 samples, even if the highest odds ratios (3.6) were associated with the density of the cell infiltrate. The disease course of T1/T2 patients was analysed according to the PCR findings. All the PCR-negative patients showed a long-standing stable disease course; on the other hand, a disease progression occurred in 12/87 (13.8%) positive patients.

CONCLUSIONS

The multiplex PCR/HD analysis is associated with a high diagnostic accuracy (92.7%) in CTCL patients. The finding of a clonal T-cell rearrangement is more closely associated with the histological pattern (in particular with the density and extent of the cell infiltrate) rather than with the MF cutaneous T-score or immunophenotype.

The usefulness of clonality for the detection of cases clinically and/or histopathologically not recognized as cutaneous T-cell lymphoma

BACKGROUND

The determination of clonality has proven to be a useful adjunct to the diagnosis of cutaneous lymphocytic infiltrates. It is considered particularly helpful for the distinction of mycosis fungoides (MF) and inflammatory dermatoses.

OBJECTIVES

To verify the sensitivity of the polymerase chain reaction (PCR)-heteroduplex analysis of T-cell receptor gamma-chain gene (TCRgamma) rearrangements in patients with MF and to establish whether a clinicopathological re-evaluation of lesions previously unclassified or considered to be non-neoplastic entities but found to be monoclonal allowed the recognition of additional cases of MF.

METHODS

Included in the study were 116 patients, seen at our Institute from April 2002 to September 2003 and tested for TCRgamma rearrangements. Thirty-six patients were affected by clinically and histopathologically proven MF, while the remaining 80 cases had not been classified or had been classified as non-neoplastic entities. The sensitivity of the molecular analysis was determined on the basis of the results obtained in the 36 patients with MF. The 29 cases of the second series of patients found to be monoclonal were clinically and histopathologically re-evaluated.

RESULTS

Clonal rearrangements were found in 87.5% of patients with plaque stage MF and in 20% of those with patch stage MF. The clinicopathological re-evaluation allowed us to reclassify 15 of 29 monoclonal cases of the second series of patients as MF.

CONCLUSIONS

The study showed that the PCR-heteroduplex technique can determine a high percentage of monoclonality only in plaque stage MF. However, in spite of the low sensitivity of the method, several cases previously unrecognized could be reclassified as MF when their clinical and histopathological features were re-evaluated taking into account the clonality of the lymphocytic infiltrate.

Histopathologic Features of Early (Patch) Lesions of Mycosis Fungoides

The histologic diagnosis of early mycosis fungoides (MF) is one of the most vexing problems in dermatopathology. We reviewed the histopathologic features of 745 biopsy specimens from 427 patients (male:female = 277:150; median age, 52 years; range, 3-95 years) with early (patch) lesions of MF collected from the lymphoma database of the Department of Dermatology of the Medical University of Graz (Austria). In all patients, the diagnosis was established by clinicopathologic correlation. The most common histopathologic pattern consisted of a band-like or patchy lichenoid infiltrate admixed with coarse bundles of collagen in the superficial dermis. Epidermotropism of lymphocytes was observed in most cases in one or more forms (single lymphocyte epidermotropism, 22%; basilar lymphocytes, 23%; Pautrier's microabscesses, 19%; "haloed" lymphocytes, 40%; disproportionate exocytosis, 17%; pagetoid epidermotropism, 3%). In 4% of cases, epidermotropism was completely missing. Atypical lymphocytes were present only in 9% of cases. Features of interface dermatitis were observed in 59% of cases. Other unusual findings were the presence of necrotic keratinocytes (23%), melanophages (8%), and extravasated erythrocytes (4%). In 28 patients, two or more biopsies taken on the same day at different body sites showed different histopathologic aspects, underlying the protean features of MF even in a single patient at a given time. Our study expands previous observations on histopathologic features of early lesions of MF. Although sometimes the histopathologic features are not diagnostic, they should be considered consistent with MF and do not rule out the diagnosis.

Assessment of T-cell Clonality via T-cell Receptor-γ Rearrangements in Cutaneous T-cell–Dominant Infiltrates Using Polymerase Chain Reaction and Single-stranded DNA Conformational Polymorphism Assay

Discerning the pathologic significance of cutaneous T-cell infiltrates can pose a diagnostic challenge for dermatopathologists. Reactive conditions such as drug-associated lymphomatoid hypersensitivity and lymphomatoid lupus erythematosus can demonstrate lymphoid atypia and a phenotype resembling cutaneous T-cell lymphoma (CTCL). Further, lymphoid dyscrasias such as pityriasis lichenoides chronica, large plaque parapsoriasis, and atypical pigmentary purpura confuse the picture because they not only mimic CTCL but also represent prelymphomatous states with inherent malignant potential. Although the emergence of a dominant clone has been considered a clue indicative of a T-cell dyscrasia, there are reports concerning the identification of monoclonality in biopsies of reactive lymphoid infiltrates. We have conducted a modified single-stranded DNA conformational polymorphism (SSCP) assay using paraffin-embedded, formalin-fixed tissue on 92 T-cell-rich biopsies to determine the relative specificity and sensitivity of this methodology. In addition, laser capture microdissection (LCM) was performed on 22 of the 92 samples to isolate the area of interest and to compare its specificity and sensitivity with those SSCP assays performed without LCM. We found that monoclonality or oligoclonality is 86% specific for preneoplastic and neoplastic states, whereas the finding of polyclonality appears to be relatively specific for a reactive process. Some cases of reversible T-cell dyscrasia produced a molecular profile mimicking lymphoma or prelymphomatous states by virtue of monoclonality or oligoclonality. Although LCM appears to improve the sensitivity for detecting preneoplastic conditions, the relative specificity appears to be the same as that encountered with routine SSCP.

The role of molecular studies in lymphoma diagnosis: a review

Lymphoma classification is based on a multiparametric approach to diagnosis, in which clinical features, morphology, immunophenotype, karyotype and molecular characteristics are important to varying degrees. While in most cases, a diagnosis can be confidently established on the basis of morphology and immunophenotype alone, a small proportion of diagnostically difficult cases will rely on molecular studies to enable a definitive diagnosis. This review discusses the various molecular techniques available including Southern blotting (SB), polymerase chain reaction (PCR), fluorescence in situ hybridisation (FISH)--including multicolour-FISH/spectral karyotyping and comparative genomic hybridisation--and also gene expression profiling using cDNA microarray technology. Emphasis is given to the analysis of antigen receptor gene rearrangements and chromosomal translocations as they relate to lymphoma diagnosis and also in the setting of minimal residual disease (MRD) detection and monitoring. Laboratories performing these tests need to have expertise in these areas of testing, and there is a need for greater standardisation of molecular tests. It is important to know the sensitivity and specificity of each test as well as its limitations and the pitfalls in the interpretation of results. Above all, results of molecular testing should never be considered in isolation, and must always be interpreted in the context of clinical and other laboratory data.

Assessment of histologic criteria in the diagnosis of mycosis fungoides

BACKGROUND

The histologic diagnosis of early mycosis fungoides (MF) can be difficult to establish in many instances because the subtle changes observed in patches of MF are also present in many inflammatory dermatoses.

METHODS

To assess the frequency and significance of many of these histologic parameters, we retrospectively reviewed 50 slides from patients with documented MF in patch, plaque, and tumor stages. The diagnosis of MF was unequivocally established either by the progression of patients to advanced stages of the disease or by indubitable histologic findings. In the second phase of the study, we compared the histologic parameters observed in 24 patch stage MF patients with those in 24 non-MF patients. The non-MF group were patients whose pathologic pattern was suspicious for MF, but who definitely did not have MF on clinical grounds. The two groups were matched by histologic pattern. Two different observers evaluated the slides and the intensities of 32 histologic parameters were graded on a four-point scale to minimize the subjective variability in the histologic reports.

RESULTS

On univariate analysis, the following parameters achieved significance in distinguishing MF from non-MF: Pautrier's microabscesses, haloed lymphocytes, disproportionate epidermotropism, epidermal lymphocytes larger than dermal lymphocytes, hyperconvoluted lymphocytes in the epidermis and dermis, absence of dyskeratosis, and papillary dermal fibrosis. None of these features proved to have additional discriminating power on multivariate analysis.

CONCLUSIONS

The efficacy of single histologic features in the diagnosis of early MF is generally poor and, to discriminate MF from its inflammatory simulators, a combination of cytologic and architectural features must be used.

Clonal heterogeneity in mycosis fungoides and its relationship to clinical course

Mycosis fungoides (MF) is a cutaneous T-cell lymphoma characterized by multifocal disease and protracted clinical course. The few studies that have assessed T-cell receptor (TCR) gene rearrangements (GRs) present at different anatomic sites in MF have generally reported a common clone. We used a previously validated 4-color polymerase chain reaction (PCR) assay to assess the size and V-family usage of TCR-gamma GRs in 102 concurrent and/or sequential morphologically involved biopsy specimens (91 skin and 11 lymph nodes) from 39 MF patients. This assay detected TCR-gamma clonal GRs in 89 samples (87%) from 36 patients (92%). In 24 patients (77%), an identical clonal GR was present in at least 2 skin samples. However, in one third of these patients, additional different clonal GRs were also noted. Four patients (13%) had clonal GRs that were distinct in different skin samples. In 3 patients (10%), no GR was detected in any sample. In a comparison of lymph node and skin samples, 8 patients had the identical clonal GRs at both sites, 2 patients had different clonal GRs, and 1 patient had no GR identified at either site. Independent of clinical stage, patients who had the same GR detected in multiple concurrent biopsy specimens at the time of diagnosis were more likely to have progressive disease than those who had different GRs (P =.04). Four-color TCR-gamma PCR analysis can uncover multiple distinct clonal GRs in different samples consistent with multiclonal or oligoclonal disease in a significant proportion of MF patients. Demonstration of identical clonal GRs in multiple biopsy specimens at the time of diagnosis may provide prognostic information related to disease progression.

Treatment of childhood mycosis fungoides with topical PUVA

Mycosis fungoides is the most common type of cutaneous T-cell lymphoma, which is usually observed in mid to late adulthood. We report 5 cases of mycosis fungoides in children, all presenting as patch- and plaque-stage disease most commonly involving the buttocks. Histologic examination showed in every case the typical features of mycosis fungoides. In 4 of the 5 cases, the infiltrating lymphocytes were characterized by the T-cell phenotype CD3(+), CD4(+), CD8(+); and in 3 cases, a monoclonal rearrangement of the T-cell receptor gamma (TCR-gamma) gene was found. Three children received topical PUVA treatment, and the other two were treated with mid-potency topical corticosteroids, resulting in complete clinical remission. A management approach to mycosis fungoides with topical PUVA may be appropriate for children.

The value of molecular analysis by PCR in the diagnosis of cutaneous lymphocytic infiltrates

The diagnosis and classification of cutaneous lymphomas remain a challenge for the clinician and dermatopathologist. This diagnostic dilemma is mainly encountered in the distinction between an early malignant lymphoma and a benign reactive lymphocytic infiltrate (pseudolymphoma). Until the beginning of the 1980s, our diagnostic tools were limited to the clinical presentation, course, and histopathology in diagnosis and classification of lymphocytic infiltrates. Advances in immunology and, in particular, in molecular genetics with the introduction of the Southern blot technique and the polymerase chain reaction (PCR) have revolutionized the diagnosis of lymphocytic infiltrates by determination of clonality. In some series, more than 90% of cutaneous T-cell lymphomas have a clonal rearrangement of the T-cell receptor gamma-chain gene, as opposed to very low percentages of rearrangement in T-cell pseudolymphomas. However, the presence of clonality does not necessarily imply malignancy. Cases of pseudolymphomas, lichen planus and pityriasis lichenoides et varioliformis acuta were reported with clonal lymphocytic proliferations. Therefore, care should be exercised in the evaluation of the results of molecular analysis, and these should always be correlated with the clinical, histological and immunophenotypic picture to arrive at the correct diagnosis. It may be expected that the molecular methods for diagnosis of lymphocytic infiltrates will be improved and refined in future, and that sensitivity and specificity will increase.

Validation of Sixteen Leukemia and Lymphoma Cell Lines as Controls for Molecular Gene Rearrangement Assays

Background: Assays for rearrangement of the immunoglobulin, T-cell receptor, bcr/abl, and bcl-2 genes are valuable tools to aid in the diagnosis of leukemias and lymphomas and are now offered by many pathology laboratories. However, there is a lack of well-characterized and validated calibrators and positive controls for these assays. We therefore evaluated 16 readily available leukemia and lymphoma cell lines for their potential use as controls.

Methods: DNA and RNA were isolated from each cell line and analyzed by Southern blot and PCR or reverse transcription-PCR (RT-PCR). Rearrangements in the IgJH, IgJκ, TcR-β or TcR-γ, bcr/abl, and bcl-2 genes were detected by commercially available probes and primers. Cell lineages were confirmed by immunophenotyping.

Results: Immunoglobulin and T-cell receptor gene rearrangements were identified in five B- and three T-cell lines, respectively. Two cell lines tested positive for the bcr/abl gene, and one was positive for the bcl-2 gene rearrangement by Southern blot.

Conclusions: The 16 cell lines studied can be used as positive controls in molecular detection assays for gene rearrangements. The parallel processing of these cell lines with clinical samples can serve to quality control the experimental procedures from the first step of DNA or RNA extraction to the final step of result analysis.

Practical evaluation and management of cutaneous lymphoma

Accurate evaluation of patients with suspected or known cutaneous lymphoma requires the integration of many sources and types of information, including clinical evaluation, microscopic analysis of tissue, immunophenotyping, gene rearrangement studies, clinical staging, and longitudinal observation. Diagnoses should be based on knowledge of specific lymphoma types as described in modern classification systems. Management of patients with cutaneous lymphoma requires collaboration among dermatologists, dermatopathologists, hematopathologists, and medical, surgical and radiation oncologists. (J Am Acad Dermatol 2002;46:325-57.)

LEARNING OBJECTIVE

At the conclusion of this learning activity, participants should better understand how to evaluate and manage patients for suspected or established lymphoma of the skin. Components include the clinical history and physical examination, optimal biopsy and tissue handling, interpretation of pathology and adjunctive test results, clinicopathologic correlation, and therapy. Participants should also understand the basis for establishing a specific diagnosis of cutaneous lymphoma based on current classification and staging.

Detection of clonal T-cell receptor-gamma gene rearrangement by PCR/temporal temperature gradient gel electrophoresis

Limited combinatorial and junctional diversity in TCR-gamma gene rearrangement can result in amplification products that are difficult to interpret when analyzed by conventional gel electrophoresis methods that separate DNA based on size (polymerase chain reaction [PCR]/polyacrylamide gel electrophoresis [PAGE]). We describe a simple approach to the detection of clonal TCR-gamma gene rearrangement using temporal temperature gradient gel electrophoresis (TTGE) that uses a gradual and uniform increase in the temperature of a constant denaturing gel to resolve different DNA molecules based on base pair composition. We tested 42 clinical specimens (30 blood specimens and 12 formalin-fixed paraffin-embedded tissues) for T-cell clonality by PCR/PAGE and PCR/TTGE. Concordant results were obtained in only 22 specimens (52%). Of the 20 discordant cases, 18 samples were positive by TTGE and negative by PAGE. For all of the discordant cases, the TTGE yielded results that correlated better with the clinical data than did the PAGE method. We conclude that PCR/TTGE is more accurate and easier to perform than current methods for detecting clonal populations of T cells.

Evaluation of a new paraffin-reactive CD7 T-cell deletion marker and a polymerase chain reaction-based T-cell receptor gene rearrangement assay: implications for diagnosis of mycosis fungoides in community clinical practice

BACKGROUND

T-cell deletion and T-cell receptor (TCR) gene rearrangement studies are helpful in the early diagnosis and subsequent management of mycosis fungoides (MF). However, this often requires fresh-frozen tissue that can be difficult to obtain and evaluate in community clinical practice. A new CD7 antibody, the most sensitive and specific T-cell deletion marker, and a new TCR-gamma gene rearrangement polymerase chain reaction (PCR) assay (TCR-gamma PCR) are now available on routine paraffin-embedded biopsy specimens.

OBJECTIVE

Our purpose was to assess the utility of CD7 deletion and TCR-gamma PCR in the diagnosis of MF using routine paraffin-embedded biopsy material.

METHODS

Cases of MF (n = 17) with matching frozen tissue immunohistochemistry and benign reactive dermatoses (lichen planus; n = 27) were assessed for CD7 (Clone: CD7-272) deletion and TCR-gamma PCR using paraffin-embedded biopsy specimens.

RESULTS

Excellent concordance comparing frozen and paraffin embedded CD7 immunostaining (88%) was observed. CD7 deletion and TCR-gamma PCR was sensitive (94%) and specific (96%) for a diagnosis of MF using paraffin-embedded biopsy specimens.

CONCLUSION

In the diagnosis of MF, detection of CD7 deletion and monoclonal TCR rearrangements can be successfully performed in a cost-effective, timely fashion using routine formalin-fixed paraffin-embedded biopsy specimens.

Polymerase chain reaction (PCR) for human herpesvirus 8 and heteroduplex PCR for clonality assessment in angiolymphoid hyperplasia with eosinophilia and Kimura's disease

BACKGROUND

Recently, human herpesvirus 8 (HHV-8) has been isolated from almost all cases of Kaposi's sarcoma. It has not been found in most cutaneous hemangioproliferative disorders other than Kaposi's sarcoma. Benign vascular lesions including Kimura's disease were not found to contain the HHV-8 DNA sequence. However, there has been contradictory data concerning the presence of HHV-8 in angiolymphoid hyperplasia with eosinophilia (ALHE). Clonality studies in ALHE and Kimura's disease were rare.

METHODS

We performed polymerase chain reaction (PCR)-based analysis to determine whether HHV-8 is present and heteroduplex analysis of rearranged T-cell receptor (TCR) gene for clonality assessment in paraffin-embedded skin biopsy samples of 7 ALHE and 2 Kimura's disease, taken from immunocompetent patients.

RESULTS

HHV-8 could not be identified in all the cases of ALHE and Kimura's disease. Although 2 cases (2/7) of ALHE and 2 cases (2/2) of Kimura's disease showed positive result for PCR analysis of TCR, all the cases were negative for heteroduplex-PCR.

CONCLUSIONS

We suggest that HHV-8 may not involve in a pathogenetic role in ALHE and Kimura's disease and the failure to demonstrate clonality may be consistent with the reactive nature of these diseases and lack of malignant transformation. In addition, heteroduplex-PCR can be applied to confirm doubtful cases of lymphoma in that heteroduplex-PCR is more specific than PCR as seen in our study.

Detection of clonal T cell receptor gamma gene rearrangements in cutaneous T cell lymphoma by LightCycler-polymerase chain reaction

Cutaneous T cell lymphoma is thought to be characterized by a monoclonal T cell infiltrate in the skin that can be detected by polymerase chain reaction-based amplification of T cell receptor gamma gene rearrangements. We sought to establish a new, simple, and fast LightCycler-based real-time polymerase chain reaction assay for the detection of monoclonality in cutaneous T cell lymphoma, which was suitable for routine laboratory application. Monoclonal T cell receptor gamma gene rearrangements were detected by polymerase chain reaction with consensus primers using: (i) a thermocycler followed by polyacrylamide gel electrophoresis; (ii) a Light Cycler followed by melting curve analysis; and (iii) a LightCycler and subsequent polyacrylamide gel electrophoresis. The detection limit of monoclonal Jurkat T cells diluted in polyclonal peripheral blood mononuclear cells was: (i) 1--3% by thermocycler--polymerase chain reaction and polyacrylamide gel electrophoresis; (ii) 10% by LightCycler--polymerase chain reaction and melting curve analysis; and (iii) 1% by LightCycler--polymerase chain reaction and polyacrylamide gel electrophoresis. In skin biopsies of 22 cutaneous T cell lymphoma patients, a monoclonal or biclonal T cell infiltrate was detected in: (i) 15 of 22 (68%) by thermocycler--polymerase chain reaction and polyacrylamide gel electrophoresis; (ii) 13 of 22 (59%) by LightCycler--polymerase chain reaction and melting curve analysis; and (iii) 16 of 22 (72%) by LightCycler--polymerase chain reaction and polyacrylamide gel electrophoresis. All three techniques revealed negative results in skin biopsies from 26 patients with benign dermatitis. In conclusion, LightCycler--polymerase chain reaction and melting curve analysis is a fast, simple and specific method to detect monoclonal T cell infiltrates in cutaneous T cell lymphoma. Sensitivity of LightCycler--polymerase chain reaction and polyacrylamide gel electrophoresis is slightly higher compared with sensitivity of thermocycler--polymerase chain reaction and polyacrylamide gel electrophoresis. Melting curve analysis, however, is less sensitive compared with polyacrylamide gel electrophoresis, and in case of negative results of the melting curve analysis, it is recommended to resolve LightCycler--polymerase chain reaction samples by gel electrophoresis.