Do environmental factors play any role in the pathogenesis of mycosis fungoides and Sézary syndrome?

From Molecules to Microbes: Tracing Cutaneous T-Cell Lymphoma Pathogenesis through Malignant Inflammation

The etiology of CTCL is a subject of extensive investigation. Researchers have explored links between CTCL and environmental chemical exposures, such as aromatic hydrocarbons (eg, pesticides and benzene), as well as infectious factors, including various viruses (eg, human T-lymphotropic virus [HTLV]-I and HTLV-II) and bacteria (eg, Staphylococcus aureus). There has been growing emphasis on the role of malignant inflammation in CTCL development. In this review, we synthesize studies of environmental and infectious exposures, along with research on the aryl hydrocarbon receptor and the involvement of pathogens in disease etiology, providing insight into the pathogenesis of CTCL.

Clusters, crop dusters, and myth busters: a scoping review of environmental exposures and cutaneous T-cell lymphoma

INTRODUCTION

Cutaneous T-cell lymphoma (CTCL) is a heterogenous group of non-Hodgkin lymphomas. Similar presentation to benign conditions, significant genetic variation, and lack of definitive biomarkers contributes to diagnostic delay. The etiology of CTCL is unknown, and environmental exposures, such as geographic, occupational, chemicals, sunlight, and insects have been investigated.

EVIDENCE ACQUISITION

Review of the literature for CTCL and exposures was performed in PubMed and Google Scholar in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) Extension for Scoping Reviews. This search yielded 193 total results, which were initially screened with defined inclusion and exclusion criteria. The 45 remaining articles were reviewed and classified by exposure type.

EVIDENCE SYNTHESIS

The most frequently investigated CTCL exposure type was geographic (13/45 articles, 29%). Chemical exposures were commonly discussed (10/45 articles, 22%), along with occupational (10/45 articles, 22%). Insect exposures (6/45, 13%) and sun exposure (3/45, 7%) were also reviewed, along with articles describing multiple exposure types (3/45, 7%). Article types ranged from cases to systematic reviews and case-control studies. Evidence linking CTCL and these exposures was mixed. Limitations of this investigation include reliance on patient reporting and frequent speculation on disease association versus causality.

CONCLUSIONS

This investigation synthesizes the current literature on exposures potentially implicated in the pathogenesis of CTCL, while offering guidance on patient history-taking to ensure potential exposures are captured. Awareness of these possible associations may improve understanding of disease pathogenesis and diagnosis. Moreover, these insights may help with public health decision-making and disease mitigation.

Cytomegalovirus: its potential role in the development of cutaneous T-cell lymphoma

To investigate the potential role of CMV in cutaneous T-cell lymphoma (CTCL), we studied cytomegalovirus (CMV) seroprevalence in parapsoriasis (PP), mycosis fungoides (MF) and Sézary syndrome (SS) compared with healthy control patients. In cases where CMV seropositivity was observed, CMV PCR analyses were performed on skin biopsies. CMV seroprevalence was 37.1% in the control group, 50.68% in the PP + MF + SS group (P = 0.08), 56.2% in the MF + SS group (P = 0.07), 40% in the PP group (P = 0.9), 66.67% in the MF group (P = 0.009), 42.86% in the SS group (P = 0.9). CMV PCR in initial skin biopsies were all negative. However, PCR CMV was positive in two SS skin biopsies realized at an advanced stage. Our results show that latent CMV infection may play a role in the susceptibility of MF in predisposed subjects by inducing T-cell proliferation and resistance to apoptosis. Concerning SS, an immunosuppressive state may be responsible for CMV reactivation that in turn may interfere with evolution of the disease.

Mycosis fungoides--analysis of the duration of disease stages in patients who progress and the time point of high-grade transformation

BACKGROUND

Mycosis fungoides (MF) is a low-grade malignant primary cutaneous T-cell lymphoma which, in its evolution, passes through five distinct stages (patch, plaque, and tumor stages, lymph node infiltration, and, finally, multiple organ infiltration). Furthermore, a blast transformation into a high-grade malignant lymphoma can occur. In order to better understand the dynamics of the disease and the prognostic implications in patients who progress, we studied the duration of each stage and the time at which blast transformation occurred.

METHODS

We reviewed the records of 48 MF patients who had been followed in the lymphoma clinic of the Department of Dermatology, University Hospital Zurich, Zurich, Switzerland for a median of 10 years. Forty-two cases were eligible for evaluation.

RESULTS

Our study showed that MF in patients who progress is a disease which, after an initial patch stage with an average duration of 7.2 years, a plaque stage lasting for an average of 2.3 years, and a tumor stage with an average duration of 1.8 years, leads to a stage of lymph node infiltration with an average duration of 0.6 years, internal organ infiltration lasting for an average of 0.5 years and, finally, a fatal outcome. Consequently, the overall average disease duration in progressing patients is 12.4 years. Blast transformation occurs in 85% of all cases in the tumor stage.

CONCLUSIONS

The course of progressing MF is chronic and advancing. The progression is initially slow and later accelerates. Important prognostic factors are the stage of disease and the presence of blast transformation. The prognosis is better in the early stage and when blast transformation is absent.

Investigation on the association between atopic dermatitis and the development of mycosis fungoides in dogs: a retrospective case-control study

In human medicine, the relationship between the immunodysregulation observed in atopic dermatitis (AD) and the development of mycosis fungoides (MF) has triggered considerable interest due to the increasing number of patients with MF who have a previous history of AD. The purpose of this retrospective case-control study was to investigate whether dogs diagnosed with MF were more likely to have AD. The records of 96 000 canine patients at the University of Florida were searched. Inclusion criteria were a clinical and histological diagnosis of MF. Dogs admitted to the University of Florida, Veterinary Medical Center during the same time period (1991-2004) without a diagnosis of MF were included as controls. Four controls for each study dog were randomly selected (matched by year of admission). Frequency of AD and other exposure variables were compared among case and control dogs by using conditional logistic regression. Records of 19 dogs with a diagnosis of MF were identified. Five of them (5/19, 26.3%) had previous diagnosis of AD. The odds of having MF was 12 times (OR = 12.54; 95% CI = 1.95-80.39; P < 0.01) higher in dogs with AD than in dogs without AD. In conclusion, this study suggests an association between AD and MF in dogs. Future studies are necessary to confirm this finding and to investigate the pathogenic mechanisms involved in this association.

Mycosis fungoides and Sezary syndrome: therapeutic approach and outcome in 113 patients

BACKGROUND

Mycosis fungoides (MF) and Sezary syndrome (SS) are the most common forms of cutaneous T-cell lymphoma (CTCL). Various topical and systemic therapeutic alternatives are available, but there is no standard or definite curative treatment regimen. When making a decision about the appropriate treatment modality, the age and compliance of the patient, stage of the disease, treatment accessibility, and previous treatment history should be considered.

AIM

To determine the therapeutic response of patients with MF and SS to different treatment modalities. Patients were evaluated with respect to their clinical and demographic features.

METHODS

One hundred and thirteen patients diagnosed clinically and dermatopathologically with MF and SS between March 1984 and June 2001 were included in the study.

RESULTS

Of the 113 patients studied, 110 had a diagnosis of MF and three had a diagnosis of SS; 101 patients (89.4%) were diagnosed with early stage (IA, IB, IIA) and 12 (10.6%) with late stage (IIB, III, IVA, IVB) disease. The age at diagnosis varied between 12 and 81 years (mean, 45.6+/-15.8 years). Fifty-five (48.7%) patients were male and 58 (51.3%) were female. The duration of the skin lesions varied between 1.5 months and 32 years (mean, 6.1 years). Psoralen plus UVA (PUVA) was the most commonly used initial treatment modality in early stage disease (91%), with a complete remission (CR) rate of 80.4%. With PUVA+interferon-alpha (INF-alpha) treatment, CR was 57% in the early stages and 33.3% in the late stages. For late stage disease, systemic therapies, such as pentostatin, gemcitabine, and fludarabine, alone or in combination with INF-alpha, were preferred. Of the 113 patients, eight (7% of the total and 57.1% of the advanced stage cases) died of MF; 21.4% of the late stage patients showed partial remission and 14.2% showed CR. None of the patients diagnosed with early stage disease died of MF, but two (1.9%) progressed to late stage disease.

CONCLUSIONS

PUVA and PUVA+INF-alpha are effective treatment modalities, especially for early stage MF. Once the disease has progressed, both MF and SS are very resistant to treatment regimens, including chemotherapeutic agents. It is important to diagnose and treat these diseases, especially MF, in the early stages for lasting remission.

From inflammation to neoplasia: new concepts in the pathogenesis of cutaneous lymphomas

Mycosis fungoides is a clinicopathologic term which describes a neoplasm of cerebriform T lymphocytes that form plaques and tumors. We further suggest that mycosis fungoides arises in a background of chronic inflammation or as a response to chronic antigenic stimulation. Subsequently, a series of mutations results in the stepwise progression from eczematous patches, to plaques, tumors and eventual hematogenous dissemination. The pathogenetic process is driven by various, probably individually different, exogenous factors, e.g. environmental foreign antigens, bacterial superantigen, and/or endogenous factors, e.g. autocrine cytokine loops, CD40/CD40L and B7/CD28 interaction.

Examination of mycosis fungoides for the presence of Epstein-Barr virus and human herpesvirus-6 by polymerase chain reaction

BACKGROUND

The aetiology of cutaneous T-cell lymphoma (CTCL) remains unknown despite numerous investigations. In recent years, retroviruses and human herpesviruses have been implicated to play a causal part in CTCL.

OBJECTIVE

The aim of this study was to elucidate the possible aetiopathogenetic role of human herpesviruses (HHV) in mycosis fungoides (MF).

METHODS

Polymerase chain reaction was used to study formalin-fixed, paraffin-embedded lesional skin biopsies from 92 subjects with MF to evidence possible presence of Epstein-Barr virus (EBV) and HHV-6.

RESULTS

Biopsy specimens from nine subjects (9.8%) evidenced EBV DNA, whereas all except one of the subjects (1.1%) lacked HHV-6 DNA.

CONCLUSIONS

Although these findings do not support a primary aetiological role for EBV and HHV-6 in classical CTCL, the possibility remains that both viruses, particularly EBV, may act as potential cofactors in the development of CTCL.

HLA-DR5 and DQB1*03 class II alleles are associated with cutaneous T-cell lymphoma

Cutaneous T-cell lymphoma (CTCL) may present with eczematous lesions, mycosis fungoides (MF), or as exfoliative erythroderma with circulating atypical cells, Sezary syndrome (SS). The "malignant" T cells are epidermotropic and clonal, but whether they respond to antigen stimulation is unknown. Because CD4+ lymphocytes recognize antigen presented by histocompatibility locus antigen (HLA) class II molecules, and HLA association have been found in autoimmune skin diseases, we determined by allele-specific oligonucleotide typing whether HLA-DR or DQ alleles were associated with CTCL and its two variants MF (n = 47) and SS (n = 23). Phenotypic frequencies were compared by chi-square and Fisher exact test, and p values were corrected independently for either 12 DR or 15 DQ alleles. HLA-DR5, previously associated with MF, was significantly increased in all 70 CTCL patients (31.5%) versus controls (11%) (uncorrected p value [Pnc] = 0.000038, odds ratio [OR] = 3.9, 1.9 < OR < 8.1), in MF patients (34%) (Pnc = 0.000047, OR = 3.62, 1.9 < OR < 10), and in SS patients (26%) (Pnc = 0.03, OR = 3, 0.9 < OR < 9.3). HLA-DQB1*03 alleles (0301, 0302, and 0303) were increased in 72% of all CTCL patients versus 49% of controls (corrected p value [Pc] = 0.014, OR = 2.7, 1.4 < OR < 5.1), in SS (82%) (Pc = 0.05, OR = 4.7, 1.4 < OR < 5), and in MF (67%) (Pnc = 0.024, OR = 2.15, 1 < OR < 4.5). DQB1*0502 was strongly increased in SS patients (Pc = 0.045, OR = 7.75, 1.25 < OR < 48). Although HLA-DQB1*0603 and HLA-DR6 (1301, 1302, and 1402) were decreased in all groups, the decreases were not statistically significant. These data suggest that certain HLA-DRB and DQB1 alleles, also associated with other T-cell-mediated skin diseases, may participate in the pathogenesis of or susceptibility to CTCL.