The value of the polymerase chain reaction in the diagnosis of cutaneous T-cell infiltrates

Granulomatous Pigmented Purpuric Dermatosis in a Patient with (Inactive) Myasthenia Gravis: A Case Report and Review of the Literature

Granulomatous pigmented purpuric dermatosis (GPPD) is a rare histologic variant of pigmented purpuric dermatosis (PPD) characterized by dermal histiocyte-rich interstitial infiltration with or without granuloma formation in addition to the other typical features of PPD. GPPD was previously observed more frequently to affect Asians and was reported to be associated with dyslipidemia. However, our literature search of 45 documented GPPD cases revealed an increasing prevalence in Caucasians in addition to dyslipidemia and associated autoimmune diseases. To date, etiopathogenesis of GPPD is unknown but may involve dyslipidemia, genetic and immunological factors such as autoimmune dysregulation or a sarcoidal reaction associated with C. acnes. GPPD is usually persistent and recalcitrant to treatments. We report a case of GPPD in a 57-year-old Thai woman with underlying myasthenia gravis who presented with a pruritic eruption on both lower legs. After treatment with 0.05% clobetasol propionate cream and oral colchicine, the lesion improved with marked flattening and disappeared with residual postinflammatory hyperpigmentation. We provide a literature review of the epidemiology, etiopathogenesis, concomitant comorbidities, clinical symptoms, dermatoscopic features, and treatments of GPPD.

A 78-Year-Old Female with a Diffuse Pruritic Rash and Palmoplantar Desquamation

Mycosis fungoides, the most common cutaneous T-cell lymphoma, is known to exhibit varied clinical presentations and mimic many other dermatoses. This morphological heterogeneity can often lead to initial misdiagnoses resulting in significant delays from symptom onset to diagnosis. We report a case of mycosis fungoides imitating clinical and histopathological features of erythema annulare centrifugum.

Mycosis fungoides and Sézary syndrome: clinical, histopathological and immunohistochemical review and update

This paper reviews the diagnostic and classificatory concepts of mycosis fungoides and Sézary syndrome in light of the latest normative publications. It describes the great variability of the clinical expression of mycosis fungoides in its early stages as well as the histopathological and immunohistochemical aspects that help with diagnosis. The diagnostic criteria required for characterizing Sézary syndrome and the staging system used for both mycosis fungoides and Sézary syndrome are described.

T-cell receptor-gamma gene analysis in evolving to advancing cutaneous T-cell lymphoma

The diagnosis of cutaneous T-cell lymphoma is often a challenge for the dermatopathologist. Early stages can mimic inflammatory dermatoses. Our aim was to explore the applicability of a standard T-cell receptor-gamma polymerase chain reaction in various subtypes of cutaneous T-cell lymphomas. Ninety-six biopsy specimens from 38 patients were selected. These included 72 specimens of mycosis fungoides, 12 specimens of non-mycosis fungoides T-cell lymphomas, and 12 specimens in which histology was non-specific or equivocal in patients who were later diagnosed to have lymphoma. T-cell clones were detected in 53 of 72 specimens of mycosis fungoides and eight of 12 specimens of non-mycosis fungoides lymphomas. Of the 72 specimens of mycosis fungoides, T-cell clones were detected in eight of 10 specimens of mycosis fungoides-associated follicular mucinosis and pigmented purpura-like mycosis fungoides. Four specimens from the 12 prediagnostic for cutaneous T-cell lymphomas showed presence of T-cell clones, identical to subsequent clones detected when lymphoma was fully established. In specimens where histology is not diagnostic and T-cell receptor-gamma gene analysis is positive, patients should be followed up closely. T-cell receptor-gamma gene analysis is a useful adjunct to histological diagnosis of early stage and variant types of mycosis fungoides.

Cutaneous Lymphomas

The skin is the most common site of extranodal non-Hodgkin lymphoma, with a yearly incidence approaching 1 per 100,000 individuals in the United States. Skin lymphomas are classified broadly into cutaneous T-cell lymphoma (CTCL) and cutaneous B-cell lymphoma (CBCL). Within these broad categories, multiple unique pathologic entities exist with a wide array of natural histories and treatment options. Radiotherapy plays an important role in the curative treatment of localized CTCL and CBCL and may be used to palliate cutaneous and visceral symptoms associated with advanced disease. This review highlights the role of radiotherapy in the multidisciplinary management of cutaneous lymphoma.

Differences in survivin location and Bcl-2 expression in CD30+ lymphoproliferative disorders of the skin compared with systemic anaplastic large cell lymphomas: an immunohistochemical study

BACKGROUND

Cutaneous CD30+ lymphoproliferative disorders (LPDs) are a spectrum of disease associated with a favourable prognosis. Systemic anaplastic large cell lymphoma (ALCL), although morphologically and phenotypically similar, differs in clinical presentation and has a less favourable biological behaviour. Dysregulation of apoptosis, the process regulating cell population by programmed death, can explain the differences among these disorders.

OBJECTIVES

We investigated the expression of two inhibitors of apoptosis, survivin and Bcl-2 protein, in serial skin lesion samples from CD30+ LPDs compared with systemic ALCL.

METHODS

Immunohistochemical analysis with antibodies against anaplastic lymphoma kinase (ALK)-1 protein, survivin and Bcl-2 protein was performed in 10 cutaneous CD30+ LPDs (five lymphomatoid papulosis, five ALCL) and 18 systemic ALCLs. Reverse transcription-polymerase chain reaction studies for ALK and ALK/nucleophosmin were also performed.

RESULTS

Cutaneous CD30+ LPDs shared a heterogeneous expression of cytoplasmic survivin with all systemic ALCLs, and of Bcl-2 with systemic ALK- ALCLs; however, they differ from systemic ALK- ALCLs because they lack nuclear survivin (P = 0.045), and from systemic ALK+ ALCLs by a higher expression of Bcl-2 (P = 0.045) and a lack of ALK-1. Overall, coexpression of Bcl-2 and nuclear survivin in CD30+ LPDs was associated with a less favourable disease survival.

CONCLUSIONS

The different patterns of expression of Bcl-2 and survivin in CD30+ LPDs might have an impact on their different biological and clinical behaviour. Moreover, nuclear localization of survivin, similarly to ALK, may be a useful marker for predicting a systemic form of ALCL with cutaneous presentation.

Molecular staging of lymph nodes from 60 patients with mycosis fungoides and Sézary syndrome: correlation with histopathology and outcome suggests prognostic relevance in mycosis fungoides

BACKGROUND

Histological evidence of lymph node involvement is associated with a poor prognosis in patients with cutaneous T-cell lymphoma (CTCL).

OBJECTIVES

To determine whether T-cell receptor (TCR) gene analysis is of prognostic relevance in CTCL.

METHODS

TCR gene analysis was performed on lymph node specimens from 60 patients with mycosis fungoides (MF) and Sézary syndrome (SS) using a highly sensitive polymerase chain reaction (PCR)/single-strand conformational polymorphism analysis and results were correlated with skin, overall clinical and histological lymph node stages.

RESULTS

The frequency with which a T-cell clone was detected in lymph node samples from patients with MF increased with skin stage, overall clinical stage and with the degree of histological involvement: six of 19 patients with uninvolved lymph nodes or limited histological involvement (LN0-2) and 13 of 14 patients with advanced histological involvement (LN3-4) had a detectable T-cell clone. In SS, 22 of 27 patients had a detectable lymph node T-cell clone. The clonal patients had a poorer prognosis than nonclonal patients (median survival from biopsy of > 72 months vs. 16 months for MF and 41.5 vs. 16.5 months for SS). Regression analysis confirmed that TCR gene analysis identifies a group of MF patients with a worse prognosis (P = 0.013). However, the molecular lymph node stage did not provide independent prognostic information in this cohort of patients in multivariate analysis.

CONCLUSIONS

Molecular staging in MF and SS using a PCR-based method for TCR gene analysis provides additional information to histological examination. Specifically, this study identified a group of MF patients with early lymph node involvement with a poorer prognosis. However, a larger prospective study of patients with MF and early histological lymph node involvement is required to confirm whether molecular staging of lymph nodes provides independent prognostic information in a multivariate model.

Clinicopathologic features and T-cell receptor gene rearrangement findings of mycosis fungoides palmaris et plantaris

BACKGROUND

Mycosis fungoides palmaris et plantaris (MFPP), characterized by hyperkeratotic patches or plaques confined to the palms and soles, is rare and easy to misdiagnose because of the clinical similarity to psoriasis, cutaneous inflammatory dermatoses, and dermatophytic infections. The literature about MFPP mostly consists of case reports with short-term follow-up.

OBJECTIVE

Our purpose was to evaluate the clinicopathologic features, T-cell receptor (TCR) gene rearrangement findings, and prognosis of MFPP.

PATIENTS AND METHODS

This retrospective study has been reviewed in the clinicopathologic, TCR gamma gene rearrangement findings and follow-up study of 12 patients with MFPP.

RESULTS

The duration of diseases ranged from 9 months to 25 years with a mean duration of 5.3 years. Clinically, hyperkeratotic patches and plaques were observed in all cases, with 6 cases having developed on the palms and soles and 6 cases on the palms only. In TNM classifications, all cases were confined to T1N0M0 (stage IA) showing an early stage of mycosis fungoides (MF). Histopathologic findings revealed marked hyperkeratosis, parakeratosis with plasma, epidermotropism, convoluted lymphocytes, haloed lymphocytes, dense infiltrate of lymphocytes in all 12 cases (100%), Pautrier's microabscess in 9 cases (75%), a wiry bundle of collagen in 11 cases (91.7%) and basilar epidermotropism in 3 cases (25%). TCR gamma gene rearrangement was performed except for one case and monoclonality was detected in 10 of 11 cases. In the comparison group with cutaneous inflammatory dermatoses, all cases showed polyclonality. Treatment was done with Re-PUVA (acitretin and PUVA), ultraviolet A1, as well as systemic acitretin and methotrexate. Most patients showed a good response. In the follow-up study of 9 cases for a mean period of 47.6 months, only one patient's skin lesions were extended to the trunk and face, but the other patients had no sign of extracutaneous involvement.

LIMITATIONS

These results were obtained from patients with MFPP in Korea. A cooperative study with other ethnic groups will be helpful.

CONCLUSIONS

If a patient has recalcitrant palmoplantar dermatosis, MFPP should be suspected and histopathologic studies with TCR gene rearrangement should be done for early diagnosis of MFPP.

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.

Long-term experience with low-dose interferon-alpha and PUVA in the management of early mycosis fungoides

OBJECTIVES

Combined high-dose Interferon-alpha and psoralen plus ultraviolet A irradiation (PUVA) have been reported to be effective in the treatment of early mycosis fungoides (MF); however, our study is the first controlled prospective study in the literature exploring the activity and tolerability of the combination with low dosages and evaluating further clinical outcome of early-MF patients.

METHODS

We carried out a multicentric prospective Phase II clinical study on 89 patients with early-stage IA to IIA MF treated for 14 months with low-dose IFN-alpha2b (6-18 MU/wk) and PUVA. Treatment success was analysed in terms of freedom from treatment failure.

RESULTS AND CONCLUSIONS

Complete remission (CR) was achieved in 84% and an overall response rate in 98% of cases: six-month CR was associated with a non-confluent skin infiltrate at histology (P = 0.044) and 14-month CR with high epidermal CD1a+ dendritic-cell density (P = 0.030). The combination protocol was successfully tolerated and the most common reason of 'failure' was related to relapse and not to toxicity. Sustained remissions were achieved in 20% of patients. High CD8+ lymphoid T-cell density was associated with a lower relapse rate (P = 0.002). We think that our combination therapy can be considered an alternative approach compared with other modalities. Good immunological host surveillance in the skin lesions seems to be an optimal basis for the therapeutic success.

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.

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.

Management of the primary cutaneous lymphomas

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 both T- and B-cell subtypes and represent a wide spectrum of disorders, which at times can be difficult to diagnose and classify. Classical therapeutic strategies include topical corticosteroids, phototherapy, radiotherapy, retinoids, extracorporeal photopheresis, topical chemotherapy, systemic chemotherapy and biological response modifiers. Newer therapies include the synthetic retinoid bexarotene, the immunotoxin conjugate denileukin diftitox, interleukin-12 and monoclonal antibodies such as alemtuzumab and rituximab.

Density of neoplastic lymphoid infiltrate, CD8+ T cells, and CD1a+ dendritic cells in mycosis fungoides

BACKGROUND/AIMS

CD8+ T cells and epidermal/dermal dendritic cells expressing CD1a are found among neoplastic CD4+ T cells in mycosis fungoides (MF) lesions. This study analysed the relation of CD8+ tumour infiltrating lymphocytes (TILs), CD1a+ epidermal Langerhan's cells (LCs), and dermal dendritic cells (DDCs) to clinicopathological parameters in 46 MF cases.

METHODS

Pretreatment diagnostic biopsy specimens of 46 MF cases were submitted to histological analysis and immunohistochemistry. Four histological grades were defined based on the density of the neoplastic infiltrate: grade 1 (mild superficial perivascular infiltrate), grade 2 (moderate superficial perivascular infiltrate with some tendency to confluence), grade 3 (pronounced superficial band-like infiltrate), and grade 4 (deep nodular infiltrate). Epidermotropism was scored as low, moderate, or high. Numbers of CD8+ T cells and of dermal and epidermal CD1a+ cells were scored as 1 (low), 2 (moderate), and 3 (high). Correlations between these parameters and clinical data (age, sex, clinical type of lesions, stage, response to treatment, and recurrence) were analysed by the chi(2) test.

RESULTS

Numbers of TILs and DDCs were associated with subepidermal infiltrates, being lower in less dense infiltrates, whereas there was no association between epidermal CD1a+ cells and the analysed parameters. Complete remission in treated patients was related to subepidermal infiltrates but not to TILs, LCs, or DDCs.

CONCLUSIONS

These results support the notion that CD8+ cells and dermal CD1a+ cells are active against tumour cells. MF with low numbers of TILs could represent an early stage of the disease, before TILs are activated against tumour specific antigens.

Criterion by criterion, mycosis fungoides

A wide variety of histologic features have been associated with mycosis fungoides. Virtually all these features can be seen at least episodically in some inflammatory conditions, and little is known regarding which histologic features are most useful in establishing a diagnosis of this challenging condition. Three recent blind histologic studies have addressed this topic, however, and their results and those of other studies are reviewed and compared herein.

Prevalence of mycosis fungoides and its association with EBV and HTLV-1 in Pakistanian patients

Mycosis fungoides (MF) is an indolent T cell lymphoma that is distinguished from other lymphomas by its initial appearance on the skin. The histologic diagnosis of MF may be difficult because there is significant overlap in the histologic features of neoplastic T-cell infiltrates and inflammatory dermatoses. This T-cell neoplasm commonly occurs in a mixed, reactive background and can show only a subtle degree of cytologic atypia, rendering histologic diagnosis difficult. In this study MF constituted 0.86% of all non-Hodgkin s lymphoma (NHL) both T and B, as compared to the Western studies which have reported 0.5% prevalence for MF of all NHL. Polymerase chain reaction (PCR) technique was used to assess T-cell clonality in paraffin-embedded skin biopsies clinically and pathologically suspicious for early MF. Out of the 14 cases diagnosed as MF, amplifiable DNA was isolated from 6 cases, which were further studied for T-cell receptor (TcR) beta, gamma, and delta chain gene rearrangements. Clonal product was seen in 4 out of 6 cases for beta, gamma, and delta TcR chain genes. Association for Epstein Barr virus (EBV) was observed in 3 out of 6 cases (50%) of MF. Although these 3 cases were positive for EBV by PCR, but were negative by in-situ hybridization (ISH). No heterogeneity was noted in these 3 cases of MF for BamHI E, K, N, and Z regions of EBV. All six cases were negative for HTLV-1 (tax region) by PCR. It was concluded that the prevalence of MF in Pakistani population is comparable to the Western data, and that EBV association to MF cases was higher than in Western studies.

Clinicopathological and genotypic aspects of anticonvulsant-induced pseudolymphoma syndrome

BACKGROUND

Pseudolymphoma syndrome (PLS) is relatively rare but can lead to death if there are extensive skin lesions, severe hepatitis, agranulocytosis and neutropenia. PLS may also give rise to harmful effects if misdiagnosed as malignant lymphoma and patients with PLS are treated unnecessarily with chemotherapy, because it may mimic histologically other lymphomas, including mycosis fungoides (MF).

OBJECTIVES

To examine the clinicopathological and genotypic features of anticonvulsant-induced PLS. Patients and methods We retrospectively reviewed clinical, laboratory and histological findings for eight cases of anticonvulsant-induced PLS, and performed T-cell receptor gene rearrangement using polymerase chain reaction with paraffin-embedded specimens from each case.

RESULTS

The causative agents were carbamazepine (four cases), phenytoin (two cases), phenobarbital (one case) and valproic acid (one case). A cross-reaction between phenobarbital and phenytoin was observed in one case. The duration from the start of anticonvulsant therapy to skin eruption was 3-24 weeks (mean 7 weeks). The skin lesions were generalized maculopapular eruptions in all cases, including one case accompanied by vesiculopustular lesions. The frequencies of the associated features were as follows: facial oedema (88%), fever (75%), lymphadenopathy (63%), and hepatomegaly (25%). Laboratory findings revealed leukocytosis, atypical lymphocytes, eosinophilia, monocytosis, neutrophilia, lymphocytosis and abnormal liver function. Histopathologically, there was similarity between PLS and MF in that epidermotrophism of atypical lymphocytes (100%) and Pautrier's microabscess-like structures (38%) were observed. However, PLS has some differences from MF that include moderate to marked spongiosis (75%), necrotic keratinocytes (63%), and infiltration of eosinophils (25%) in the epidermis and, in the dermis, papillary dermal oedema (100%), extravasated erythrocytes (100%), lymphocytes within the dermis larger than those within the epidermis (63%), and infiltration of various inflammatory cells including neutrophils (50%). Genotypic analysis demonstrated a rearrangement of the T-cell receptor-gamma gene in one of eight cases studied. There were no deaths and all cases were improved at 2-9 weeks (mean 6 weeks), after the cessation of causative agents, systemic and topical corticosteroid therapy, and symptomatic therapy. There were no significant differences in clinical, laboratory and histological findings between the causative agents.

CONCLUSIONS

PLS may show histopathological findings similar to MF and take a prolonged course even after the cessation of causative agents. Thus, a clear understanding and diagnosis of this disease is considered to have an important effect on treatment and prognosis.

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.

A case of follicular mycosis fungoides with follicular mucinosis: a rare association

Follicular mycosis fungoides (FMF) is a rare cutaneous T cell lymphoma characterized by an atypical lymphoid infiltrate spreading within and around hair follicles without epidermotropism or follicular mucin deposits. Its occasional presentation with minimal epidermal involvement and/or follicular mucinosis suggests the need for uniform histologic criteria. We describe a new case of FMF associated with follicular mucinosis and discuss its morphologic spectrum of presentation.

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.

Comparative evaluation of PCR-based methods for the assessment of T cell clonality in the diagnosis of T cell lymphoma

AIMS

The accurate diagnosis of T cell lymphoma often depends on the demonstration of a monoclonal T cell population in a lymphoproliferative disorder (LPD). The aim of this study was to evaluate four polymerase chain reaction (PCR)-based methods used to analyse T cell receptor (TCR) gene rearrangements in the assessment of T cell clonality.

METHODS

DNA was tested from 23 T cell neoplasms, seven B cell non-Hodgkin's lymphomas (B-NHL), three Hodgkin's lymphomas (HL), 14 benign LPD and peripheral blood from a healthy donor. TCRgamma rearrangements were assessed by McCarthy's et al. two primer set method, Benhattar's et al. linear pre-amplification method, and Chhanabhai's et aL heteroduplex method. TCRbeta D-J rearrangements were analysed by Slack's et al. method.

RESULTS

Monoclonal TCRgamma rearrangements were found in 91% (21 of 23) of T cell neoplasms using McCarthy's et al. method; in 83% (19 of 23) using Benhattar's et al. or Chhanabhai's et al. methods and monoclonal TCRbeta rearrangements were found in 43% (10 of 23) using Slack's et al. method. Monoclonality was established in all T cell neoplasms using one or more PCR methods. One follicular B-NHL had inappropriate monoclonal TCRbeta rearrangement, while the remaining B-NHL and all HL samples had no monoclonal TCRgamma or TCRbeta rearrangements. In addition to polyclonal products, one reactive lymph node had oligoclonal TCRgamma rearrangements and two others generated monoclonal products of uncertain significance. McCarthy's et al. TCRgamma method was the most sensitive in establishing T cell monoclonality, and in combination with Slack's et al. TCRbeta method, monoclonality was demonstrated in 100% of T cell neoplasms (23 of 23).

CONCLUSIONS

These data indicate that multiple primer set PCR methods should obviate a need for the more expensive and time-consuming Southern blot (SB) technique and are the preferred diagnostic molecular test for assessing T cell clonality.

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.

New insights into the applicability of T-cell receptor gamma gene rearrangement analysis in cutaneous T-cell lymphoma

BACKGROUND

Detection of clonal T-cell receptor (TCR) gamma gene rearrangement by polymerase chain reaction (PCR) based method is a marker for cutaneous T-cell lymphoma (CTCL) although it can be seen in some benign dermatoses. To determine the accuracy of histologic criteria alone as well as the adjuvant diagnostic role of TCR gene rearrangement for the diagnosis of CTCL, we studied 100 patients with cutaneous T-cell infiltrates by both histology and TCR gene rearrangement.

METHODS

The histologic features of the 100 patients were first reviewed by two independent dermatopathologists and their confidence in the diagnosis of CTCL was assigned one of four levels. Then the specimens were analyzed for TCR gene rearrangement either on paraffin-embedded or fresh-frozen tissue by PCR/denaturing gradient gel electrophoresis (DGGE).

RESULTS

The clonality was detected in 100% (15/15) diagnostic of, 84.6% (11/13) consistent with, 57.6% (19/33) suggestive of CTCL. In 9 cases TCR gene rearrangement was compared between formalin-fixed and fresh specimens of the same individual, but with different degrees of histologic confidence (no lower than suggestive). In all cases fresh specimens were positive. In 5 of the cases (2-diagnostic, 2-consistent, 1-suggestive) formalin-fixed specimens were positive as well, and in 4 cases (1-consistent, 3-suggestive) formalin-fixed specimens were negative. When TCR gene rearrangement was studied in eight cases on sequential biopsies from the same patient, the clonality was detected in only one or two biopsies in four cases in which the histologic confidence was low (suggestive or nondiagnostic). The TCR gene rearrangement study showed identical banding patterns in lesions from different clinical stages in most patients. However, we observed that in one case, oligoclonal-banding pattern was seen in initial biopsy with histopathologic consistent with CTCL, while monoclonal banding pattern in more advanced lesion.

CONCLUSIONS

Our data have demonstrated that TCR gene rearrangement studies by PCR/DGGE are consistently positive regardless of tissue fixation (formalin-fixed, paraffin-embedded vs. fresh-frozen tissue) and biopsy site when the histologic degree of confidence is very high (diagnostic). So, it may be of less importance as an adjuvant to histopathologic diagnosis for the cases with diagnostic CTCL histology. However, TCR gene rearrangement studies are particularly important in earlier cases with less conclusive histology, which provides strong confirmatory evidence of an evolving CTCL. In these cases, multiple biopsies may be required to establish the diagnosis and analysis of fresh tissue is suggested to increases the sensitivity. Moreover, our observation also suggested that some CTCL might not be monoclonal de novo, but oligoclonal instead.

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.

The value of clonality in the diagnosis and follow-up of patients with cutaneous T-cell infiltrates

The diagnosis of early stages of cutaneous T-cell lymphoma (CTCL) is often difficult, especially for lesions that are at the borderline between reactive and neoplastic skin T-cell infiltrates. T-cell monoclonality in these lesions is considered by some to be an important prognostic factor of neoplastic evolution, whereas others claim that clonality can also be found in benign skin infiltrates and is therefore of limited diagnostic value. To address this controversy, the authors analyzed retrospectively eight patients with lymphocytic skin lesions who progressed to CTCL, and three patients with recurrent T-cell lymphocytic infiltrates who had not developed CTCL. From a total of 65 biopsies of eight progressing patients, 32 were diagnosed as histologically malignant and 33 were diagnosed as benign or borderline. The authors found clonality by either polymerase chain reaction or Southern blot analysis in 88% of malignant and in 79% of nonmalignant lesions. None of the 37 biopsies of non-progressing patients was clonal. These results indicate strongly that the presence of monoclonality in T-cell skin infiltrates is related closely to the risk of developing CTCL. The value of clonality as a marker of malignancy is supported by the absence of T-cell clonal populations in all infiltrates from patients who had not progressed to lymphoma.

Comparison of capillary electrophoresis and polyacrylamide gel electrophoresis for the evaluation of T and B cell clonality by polymerase chain reaction

Polymerase chain reaction (PCR) technique is widely used in the diagnosis of lymphoma, and PCR amplification products are typically detected by polyacrylamide gel electrophoresis (PAGE). However, the identification of small clonal populations, or the distinction of clonal PCR products in a polyclonal milieu remains difficult, requiring technically demanding alterations to gel analysis. This study describes an alternative approach using a capillary electrophoresis (CE) system to produce an accurately sized electropherogram. A variety of patient samples were examined, including solid tissue, peripheral blood, bone marrow aspirates, and paraffin-embedded tissue. A total of 28 samples were evaluated by PCR for B-cell clonality by detection of immunoglobulin heavy chain gene rearrangement and 29 samples for T-cell clonality by detection of T-cell gamma locus gene rearrangement. Standard 10% PAGE analysis of PCR products was compared with CE. There was a 100% concordance in the assessment of both B-cell and T-cell clonality. Dilution studies with the SUP-B15 cell line showed a detection limit of 0.03% for B-cell clonality and 0.05% for T-cell clonality using CE, versus 0.2% to 1%, respectively for PAGE. Automated, fluorescent analysis of PCR products by CE seems to be at least equally as effective as gel-based analysis for the detection of clonal B-cell and T-cell populations. Moreover. CE offers superior resolution and improved sensitivity, thus representing a significant improvement over traditional gel electrophoretic techniques in these regards.

PCR-heteroduplex analysis of T-cell receptor gamma gene rearrangement in paraffin-embedded skin biopsies

We developed a rapid, simple, and sensitive method for the detection of T-cell receptor-gamma (TCRgamma) gene rearrangements in paraffin-embedded skin biopsies. Available techniques often require either fresh tissue, several primer pairs, nested amplifications, or specialized electrophoresis steps such as denaturing gradient gel electrophoresis. Our method is based on heteroduplex analysis of polymerase chain reaction (PCR) products of the TCRgamma in a nondenaturing modified polyacrylamide gel using a single pair of primers and is adapted for paraffin-embedded tissue. When tested against Southern blot analysis, the PCR results correlated in 8 of 9 cases. Six mature cutaneous B-cell lymphomas and 29 inflammatory skin disorders all resulted in a polyclonal amplification pattern. When analyzing 3-mm or 4-mm punch biopsies of 51 cases of cutaneous T-cell lymphoma, 37 (72.5%) showed a clonal rearrangement with this technique. For 7 cases of patch stage mycosis fungoides, frozen tissue and formalin-fixed and paraffin-embedded tissue was available, and in 5 of 7 cases (71%), the results in frozen and paraffin-embedded tissue were concordant. One case showed a clonal pattern in frozen tissue but not in paraffin-embedded tissue, and one case was polyclonal in frozen tissue but monoclonal in paraffin-embedded tissue. Using serial dilutions of DNA from a T-cell ALL in a polyclonal background (tonsil), we established a sensitivity of 0.5%. Heteroduplex PCR of the TCRgamma is a rapid, sensitive, and inexpensive screening procedure as well as a useful adjunct to histologic analysis and immunophenotyping of cutaneous T-cell proliferations.

High detection rate of T-cell receptor beta chain rearrangements in T-cell lymphoproliferations by family specific polymerase chain reaction in combination with the GeneScan technique and DNA sequencing

The distinction between benign polyclonal and malignant monoclonal lymphoid disorders by morphology or immunophenotyping is frequently difficult. Therefore, the demonstration of clonal B-cell or T-cell populations by detecting identically rearranged immunoglobulin (Ig) or T-cell receptor (TCR) genes is often used to solve this diagnostic problem. Whereas the detection of rearranged Ig genes is well established, TCR gamma (γ) and beta (β) gene rearrangements often escape detection with the currently available polymerase chain reaction (PCR) assays. To establish a sensitive, specific, and rapid method for the detection of rearranged TCR-β genes, we developed a new PCR approach with family-specific Jβ primers and analyzed the resulting PCR products by high-resolution GeneScan technique. The superior efficiency of this new method was demonstrated by investigating 132 DNA samples extracted from lymph node and skin biopsy specimens (mostly formalin fixed) and blood samples of 62 patients who had a variety of T-cell lymphomas and leukemias. In all but 1 of the tumor samples (98.4%) a clonal amplificate was detectable after TCR-β PCR and the same clonal T-cell population was also found in 15 of 18 (83%) of the regional lymph nodes and in 7 of 11 (64%) of the peripheral blood samples. Direct comparison of these results with those obtained currently by the most widely applied TCR-γ PCR revealed an approximate 20% lower detection rate in the same set of samples than with the TCR-β PCR method. These results indicate that the new TCR-β PCR is most suitable for a rapid and reliable detection of clonal T-cell populations.

High detection rate of T-cell receptor beta chain rearrangements in T-cell lymphoproliferations by family specific polymerase chain reaction in combination with the GeneScan technique and DNA sequencing

The distinction between benign polyclonal and malignant monoclonal lymphoid disorders by morphology or immunophenotyping is frequently difficult. Therefore, the demonstration of clonal B-cell or T-cell populations by detecting identically rearranged immunoglobulin (Ig) or T-cell receptor (TCR) genes is often used to solve this diagnostic problem. Whereas the detection of rearranged Ig genes is well established, TCR gamma (γ) and beta (β) gene rearrangements often escape detection with the currently available polymerase chain reaction (PCR) assays. To establish a sensitive, specific, and rapid method for the detection of rearranged TCR-β genes, we developed a new PCR approach with family-specific Jβ primers and analyzed the resulting PCR products by high-resolution GeneScan technique. The superior efficiency of this new method was demonstrated by investigating 132 DNA samples extracted from lymph node and skin biopsy specimens (mostly formalin fixed) and blood samples of 62 patients who had a variety of T-cell lymphomas and leukemias. In all but 1 of the tumor samples (98.4%) a clonal amplificate was detectable after TCR-β PCR and the same clonal T-cell population was also found in 15 of 18 (83%) of the regional lymph nodes and in 7 of 11 (64%) of the peripheral blood samples. Direct comparison of these results with those obtained currently by the most widely applied TCR-γ PCR revealed an approximate 20% lower detection rate in the same set of samples than with the TCR-β PCR method. These results indicate that the new TCR-β PCR is most suitable for a rapid and reliable detection of clonal T-cell populations.

Detection of clonal T cell populations by high resolution PCR using fluorescently labelled nucleotides; evaluation using conventional LIS-SSCP

AIMS

To detect clonal T cell populations by high resolution polymerase chain reaction (PCR) using fluorescently labelled nucleotides and analysis on an ABI 377 DNA sequencer, and to evaluate this method using low ionic strength single strand conformation polymorphism (LIS-SSCP) analysis.

METHODS

DNA samples from 11 patients diagnosed with a T cell disease and 15 with no known T cell disorder were amplified using four multiplex T cell receptor gamma (TCR gamma) PCR reactions containing fluorescently labelled nucleotides. PCR products were analysed using both LIS-SSCP electrophoresis and an ABI 377 DNA sequencer using Genescan software. A Jurkat T cell leukaemia cell line was used to determine the sensitivity of the two methods.

RESULTS

Clonal TCR gamma populations were detected in all 11 samples from patients with a T cell disease and no clonal populations were detected in samples from patients without a T cell disorder, using both LIS-SSCP and DNA sequencer analysis. Although the sensitivity of the two methods was comparable, the data generated by the sequencer were easier to interpret than the LIS-SSCP gels, and allowed accurate size determination of every product, which was not possible using LIS-SSCP.

CONCLUSIONS

The use of fluorescent labelled nucleotides provides a more flexible and economical alternative to end labelled fluorescent primers for the detection of clonal TCR gamma gene rearrangements. This method allows clonal populations to be sized accurately and reproducibly, permitting the detection of identical clonal populations in different samples, and providing a method of monitoring disease progression and response to treatment.

T-cell clonality determination using polymerase chain reaction (PCR) amplification of the T-cell receptor gamma-chain gene and capillary electrophoresis of fluorescently labeled PCR products

We compared the effectiveness of polymerase chain reaction (PCR) and DNA blot analysis (DBA) for detecting clonal T-cell populations and investigated whether a nonradioactive PCR method could be used in routine clinical diagnosis. We analyzed DNA from 117 cases for T-cell clonality by PCR amplification. DBA was performed on 77 of these cases. Denaturing polyacrylamide gel electrophoresis (PCR-PAGE) of radiolabeled PCR products and capillary electrophoresis (PCR-CE) of fluorescently labeled PCR products were used for PCR product separation and quantitation. Complete agreement was obtained between PCR-PAGE and DBA in 67 of 77 cases. One case was positive by DBA and negative by PCR-PAGE, and 3 cases were positive by PAGE and negative by DBA. Five cases indeterminate by DBA were positive by PCR-PAGE, and 1 indeterminate case was negative by PCR-PAGE. In the comparison of PCR-PAGE and PCR-CE, of 63 cases with height ratios less than 2.0, all were negative by PCR-PAGE. Of 52 cases with height ratios of 2.0 or more, 50 were positive by PCR-PAGE. We conclude that PCR-CE is analytically equivalent to DBA and PCR-PAGE for detecting clonal T-cell populations. The PCR-CE method is semiquantitative and, therefore, may be more objective than gel-based methods.

Monoclonality of intraepidermal T lymphocytes in early mycosis fungoides detected by molecular analysis after laser-beam-based microdissection

The identification of neoplastic lymphocytes in early lesions of mycosis fungoides is difficult because of the scarcity of the infiltrate and the presence of reactive T lymphocytes admixed with neoplastic cells. Molecular analysis of the T cell receptor gene rearrangement using the polymerase chain reaction technique demonstrates monoclonality only in a proportion of these cases. The exact location of the malignant clone is unknown, and at present it is not clear whether neoplastic cells in early lesions reside within the epidermis, the superficial dermis, or both. We analyzed skin lesions from five patients with early mycosis fungoides using the polymerase chain reaction technique after microdissection of the specimens. In each case the epidermis was separated from the dermis using a laser-beam microdissection technique. Three samples were prepared from each lesion: one containing only the epidermis, one only the superficial dermis, and one the entire specimen. A distinct band could be observed in the epidermal sample in four cases, indicating the presence of an intraepidermal monoclonal population of T lymphocytes. The dermal sample revealed a monoclonal pattern in two cases (both of them showing clonality also within the epidermis). Analysis of the entire specimen revealed a monoclonal pattern only in two cases. Our results demonstrate that intraepidermal lymphocytes in early mycosis fungoides often show a monoclonal pattern of T cell receptor gene rearrangement. Microdissection of biopsy specimens may enhance the sensitivity of the polymerase chain reaction technique.

Analysis of T-cell antigen receptor gamma chain gene rearrangement by polymerase chain reaction in combination with denaturing gradient gel electrophoresis in the differential diagnosis of cutaneous T-lymphoproliferative diseases

A polymerase chain reaction (PCR)-based strategy has been developed for analysis of clonal rearrangement of the T-cell receptor gamma gene (TCR gamma) and was shown to be useful for detection of clonal T-cell populations. In this study, we performed PCR combined with denaturing gradient gel electrophoresis (DGGE) on fresh frozen biopsy samples from 16 patients with cutaneous T-lymphoproliferative diseases in whom a definite diagnosis was difficult to make on morphological and immunohistochemical grounds alone. Ages of the patients at biopsy ranged from 28 to 81 (median 62) years, and the subjects consisted of 8 men and 8 women. They presented with erythema on the extremities in 5 cases, trunk in 7, buttock in 2, and papules on the trunk and face in one case each. Clonal rearrangement of TCR gamma was observed in 3 of 16 cases. Clinical diagnoses of these three cases were mycosis fungoides, cutaneous invasion of adult T-cell leukemia (ATL), and large granular lymphocytic leukemia (LGL) of T-cell type, respectively, but they were histologically difficult to differentiate from reactive cutaneous T-cell proliferation. The skin lesions of the LGL case worsened, and this patient died two years after biopsy. Another patient with suspected mycosis fungoides in the plaque stage died due to dissemination of tumors 22 months after biopsy. The remaining one patient with ATL survived with cutaneous lesions for over four years. Clonality was not demonstrated in the remaining 13 cases, and their clinical courses were favorable. These findings showed that demonstration of clonal TCR gamma gene rearrangement using the PCR-DGGE method is very helpful for diagnosis of cutaneous T-cell neoplasms.

Efficacy of Histologic Criteria for Diagnosing Early Mycosis Fungoides

The correct classification of lymphoproliferative disorders provides valuable information regarding subsequent clinical evolution of the disease. The ability of pathologists to distinguish such lesions is generally low, especially when dealing with minimal lymphoid infiltrates. To improve the efficacy of histopathology in the diagnosis of early lesions of mycosis fungoides (MF), we reviewed 24 skin biopsies from 18 patients with patch stage lesions of MF early in the course of their disease and 13 slides of lichenoid, spongiotic, or psoriasiform simulators of MF as a control series. A series of cytoarchitectural features was assessed, and differences in the distribution of histopathologic parameters between the two groups (early MF lesions and MF simulators) were evaluated by the chi-square test and Fisher's exact test. For these parameters, sensitivity and specificity also were calculated. A multivariate log-linear analysis was performed to estimate which of the morphologic parameters yielded independent diagnostic information. We found that the most important feature for the diagnosis of lymphoma was the presence of lymphocytes with extremely convoluted, medium-large (7-9 microm in diameter) nuclei (medium-large cerebriform cells), singly or clustered in the epidermis and in small sheets in the dermis. Additional significant histologic features were epidermotropism as single cells lined up along the basal keratinocytes of the dermal-epidermal junction, absence of significant papillary dermis fibrosis, and absence of significant numbers of dermal blastlike cells. We conclude that the efficacy of single histopathologic features in the diagnosis of early MF is generally poor. Only the presence of medium-large cerebriform cells in the epidermis or in clusters in the dermis proved to be a highly reliable feature. However, the histopathologic diagnosis of early MF lesions and their discrimination from inflammatory simulators can be achieved using the constellation of cytoarchitectural parameters proposed.

Polymerase chain reaction/denaturing gradient gel electrophoresis (PCR/DGGE): sensitivity, band pattern analysis, and methodologic optimization

Polymerase chain reaction/denaturing gradient gel electrophoresis (PCR/DGGE) has been gaining popularity as a preferred method to determine the clonality of T-cell populations in small or sparsely infiltrated specimens such as skin biopsies. T-cell receptor (TCR)-gamma gene rearrangements are amplified using nested consensus primers in two rounds of PCR and then are separated by DGGE. Sensitivity is better than with conventional Southern blot analysis but not fully defined. In addition to a discrete primary band resulting from a monoclonal TCR-gamma gene rearrangement, there are often weaker secondary bands of unknown origin. Our goals were to define the PCR/DGGE clonal detection threshold, determine the genesis of the multiband pattern, and optimize methods to minimize extraneous bands. Titration studies showed that the sensitivity of PCR/DGGE for detecting clonal T-cell DNA is affected by the polyclonal T-cell content of the background DNA. The detection threshold is 0.001% using keratinocyte DNA as diluent but only 1% with tonsil DNA. Analysis of monoclonal T-cell lines showed that multiple bands can be produced by a single TCR-gamma gene rearrangement. Mixing of inner and outer primer pair PCR products showed that this is an artifact resulting from different sized PCR products produced during the two rounds of nested PCR required for optimal specificity. Repeat DGGE of isolated bands ruled out variable mobility of partially melted PCR products. Reduction of first round PCR product used as second round target from 10 microl to 1 microl, or a decrease of first round primers from 40 pmole to 5 pmole, resulted in diminished secondary bands without compromising primary band intensity. These results show that: 1) PCR/DGGE has a realistic clonal detection threshold of 0.1% to 1%, 2) multiple bands are consistent with a monoclonal T-cell population, and 3) conditions can be optimized to minimize artifactual secondary bands.

How useful are T-cell receptor gene rearrangement studies as an adjunct to the histopathologic diagnosis of mycosis fungoides?

The diagnosis and differential diagnosis of mycosis fungoides (MF) is often difficult, clinically and histologically. Recent attempts to enhance diagnostic sensitivity have involved T-cell receptor (TCR) gene rearrangement studies, using Southern blot or polymerase chain reaction (PCR) technique. PCR is more widely used because of its increased sensitivity, lower labor- and cost-intensive analytic steps, lack of radioactive substances, and applicability to routinely processed biopsies. Several studies that use this technique detect clonal bands in 50% to 83% of the MF specimens from patch, patch/plaque, and erythrodermic stages, which often pose a diagnostic challenge. This compares with no clonality in the control groups of most of these studies, or with up to 13% in a few studies, although long-term follow-up reveal that some cases of so-called "clonal dermatitis" eventually progress into overt cutaneous T-cell lymphoma. Furthermore, retrospective studies on archival histologic material from patients with MF demonstrate similar rates of clonality in histologically "inconclusive," "borderline," and diagnostic MF biopsies. Therefore, in the proper clinicopathologic setting, and with consideration of the known limitations of this technique, TCR gene rearrangement studies on lesional skin using PCR may be helpful as an adjunct to the histopathologic diagnosis of MF.

Chester-Erdheim disease: a neoplastic disorder

Chester-Erdheim disease is a rare non-langerhans cell histiocytosis characterized by a xanthomatous infiltration of foamy macrophages. The cause and pathogenesis remain unclear. The aim of the present study was to determine whether Chester-Erdheim disease is a polyclonal reactive disease or a clonal neoplastic disorder. The clonal status of samples obtained from five patients with Chester-Erdheim disease was studied. DNA was extracted from fixed and paraffin-embedded sections after microdissection and clonal status was studied using the Xchromosome inactivation pattern of the human androgen receptor gene (HUMARA assay). One patient was homozygous for the HUMARA gene and noninformative. Three other cases were monoclonal. One was polyclonal, and this case showed a dense reactive infiltrate in association with spumous macrophages. This study suggests strongly that Chester-Erdheim disease is a monoclonal lesion consistent with neoplastic disorder. Thus, Chester-Erdheim disease may be considered as the "macrophage" counterpart of Langerhan's cell histiocytosis in the histiocytosis spectrum. Further studies are needed to establish the origin of this clonal proliferation.

Use of the polymerase chain reaction in the evaluation of cutaneous T-cell infiltrates

Histologic evaluation of suspected cutaneous T-cell neoplasia is challenging. There is significant overlap with features of benign condition, and neoplastic cells often occur in a reactive background. Recently, molecular techniques using paraffin-embedded tissue have been applied to the diagnosis of cutaneous T-cell infiltrates. These methods are useful for determining whether a clonal population of T-cells is present. The advantages and limitation of molecular diagnostic methods in the diagnosis of cutaneous T-cell infiltrates are discussed.

Cutaneous T-cell lymphoma. Refinement in the application of controversial histologic criteria

The term cutaneous T-cell lymphoma was originally coined to encompass the spectrum of mycosis fungoides and Sézary syndrome. It has become increasingly evident that the histopathologic diagnosis of CTCL can be exceedingly challenging. A series of recent studies, however, have helped clarify the nature of the histologic findings in CTCL. Recently reported histologic data on mycosis fungoides, Sézary syndrome, and their variants is emphasized in this article, with special focus given to the findings in early lesions. A brief summary of lymphocyte immunophenotyping and the role of T-cell reception gene rearrangements in CTCL is included.

Reactive and neoplastic lymphocytes in human bone marrow: morphological, immunohistological, and molecular biological investigations on biopsy specimens

BACKGROUND

Slight, diffuse or focal lymphocyte proliferation is relatively common in bone marrow biopsy specimens. It may be impossible to determine whether this represents a reactive lymphocytosis or low grade non-Hodgkin lymphoma (NHL) on the basis of routine investigations alone.

AIM

To investigate the supplementary use of molecular biological techniques in this situation.

METHODS

529 formalin fixed, paraffin embedded bone marrow biopsy specimens from the iliac crest were subjected to histological and immunohistochemical staining to determine the number and nature of the lymphocytes present. The cases were divided into three groups according to the lymphocyte count: normal (< 10% of nucleated bone marrow cells), slightly increased (10-30%), and markedly increased (> 30%). All of the last group could be diagnosed as NHL from the morphological findings alone. The clonality of rearrangements of the IgH and TCR gamma genes was investigated by polymerase chain reaction (PCR).

RESULTS

Monoclonality was observed in 7.5% of the 372 cases with a normal lymphocyte count, in 50% of the cases with a modest increase in lymphocyte numbers (suggesting a diagnosis of low grade NHL not detected by immunostaining), and in 77% of the cases with markedly increased lymphocyte numbers.

CONCLUSIONS

If PCR is used in addition to the immunohistochemical investigation of bone marrow biopsies, considerably more cases of NHL can be identified, making this of particular use in staging and detection of recurrences.

Granulomatous mycosis fungoides: report of a case with some histopathologic features of granulomatous slack skin

We describe a case of granulomatous mycosis fungoides, tumor stage, mimicking sarcoidosis in an 82-year-old man with a 2-year history of skin disease. The final diagnosis was established after one of seven biopsy specimens showed a nongranulomatous histologic picture of patch-stage mycosis fungoides. Monoclonality was proven for the lymphocytic population by T-cell-receptor rearrangement studies. The unusually extensive granulomatous inflammation with huge giant cells surrounded by CD1a-positive cells in the other six biopsy specimens was suggestive of the histopathology of granulomatous slack skin, another rare granulomatous cutaneous T-cell lymphoma. Because both a clinical and histologic overlap between granulomatous mycosis fungoides and granulomatous slack skin have been reported in the literature, we conclude that they may belong to the spectrum of a single disease.

Analysis of clonality of atypical cutaneous lymphoid infiltrates associated with drug therapy by PCR/DGGE

Atypical lymphocytic infiltrates that mimic cutaneous lymphoma (ie, pseudolymphoma) are often observed in skin biopsy specimens from patients with altered immune function. The latter may reflect systemic immune dysregulatory states such as collagen vascular disease or human immunodeficiency virus infection. Among the iatrogenic causes are drug therapy with agents that abrogate lymphocyte function. These drugs encompass the anticonvulsants, antidepressants, phenothiazines, calcium channel blockers, and angiotensin-converting enzyme inhibitors. The appellation of lymphomatoid hypersensitivity reaction has been applied to cases of drug-associated pseudolymphoma. Pathologically and clinically, the distinction of such cases from cutaneous lymphoma is difficult. We employed the polymerase chain reaction (PCR) on archival material of proven drug-associated lymphomatoid hypersensitivity reactions both to explore its utility as an adjunct in diagnosis and to investigate the genotypic aberrations induced by drug therapy. Formalin-fixed, paraffin-embedded biopsy specimens from seven cutaneous T-cell lymphomas (CTCL), one nodal T-cell lymphoma, two cutaneous B-cell lymphomas, three typical hypersensitivity reactions, one tonsil, and 14 lymphomatoid hypersensitivity reactions were studied. Control cases for which DNA derived from fresh tissue was used include the Jurkat T-cell tumor line, placenta, one nodal B-cell lymphoma, and one case of reactive lymph node hyperplasia. DNA was obtained and purified by standard methods, then amplified with oligonucleotide primers specific for the T-cell receptor gamma locus and the immunoglobulin heavy chain genes. T-cell amplicons were analyzed by denaturing gradient gel electrophoresis (DGGE) and B-cell amplicons by either nondenaturing polyacrylamide or agarose gel electrophoresis. The nodal and Jurkat T-cell lymphomas, six of seven CTCL, one cutaneous B-cell lymphoma, and 2 of 14 lymphomatoid hypersensitivity reactions showed dominant ("monoclonal") T-cell gene rearrangement patterns, and the remainder of cases were polyclonal. A causal relationship between drug therapy and skin eruption was ascertained in the two patients showing T-cell rearrangements, and both experienced complete and sustained lesional resolution on discontinuation of the implicated drug. The only immunoglobulin heavy chain gene rearrangements detected by PCR were in two of the three B-cell lymphomas. We conclude that PCR/DGGE is a powerful method for assaying T-cell clonality in archival tissue and can aid in the discrimination of reactive from malignant cutaneous infiltrates with appropriate clinicopathologic correlation. Recognition that a monoclonal TCRgamma rearrangement can be observed in cases of drug-associated lymphomatoid hypersensitivity may help in avoiding a misdiagnosis of malignant lymphoma.

Radiotherapy for unilesional mycosis fungoides

PURPOSE

To evaluate the treatment outcome and natural history of patients with the diagnosis of unilesional mycosis fungoides, treated according to a prospective radiotherapy protocol in our institution since July 1975.

METHODS AND MATERIALS

A total of 325 patients with the diagnosis of mycosis fungoides have been referred to the Department of Radiation Oncology at Allegheny University of Health Sciences from July 1975 through September 1996. Of these, 18 patients (5%) were classified as having unilesional mycosis fungoides and were irradiated with a curative intent using local electron fields. One patient received 22 Gy; 1 patient received 40 Gy, and the rest of the patients 30.6 Gy. Daily fractions ranged from 1.8 to 2.0 Gy. Treatments prior to radiation consisted of topical steroids and/or antifungal creams in the majority of patients, with temporary partial responses. One patient had received 2 years of topical mechlorethamine (HN2) and another patient had received topical carmustine solution (BCNU) without response prior to irradiation.

RESULTS

The responses were measured clinically; posttreatment skin biopsy was not performed routinely unless there was clinical evidence of disease persistence. Complete response rate was 100%; all treated lesions cleared completely within 4 to 8 weeks after the completion of radiation. With a median follow-up of 43 months (range 12 to 240 months), 2 relapses have occurred, 2 and 71 months after the completion of radiation. Both relapses were confined to the skin and were remote from the original site. Both relapses responded to topical application of HN2. There have been no recurrences in the irradiated field nor systemic dissemination. No long-term side effects were found related to treatment, and all the patients are currently alive and without evidence of disease. Actuarial relapse-free and overall survival at 10 years are, respectively, 86.2% and 100%.

CONCLUSION

Unilesional mycosis fungoides has a long natural history, is possibly the earliest manifestation of a malignant process, and local treatments, including local radiotherapy, result in long-term disease-free intervals and, possibly, cure. Total skin electron beam radiotherapy is not indicated for this disease entity.