Benign Inflammatory Dermatoses Research Articles

蕈样肉芽肿皮损中TOX蛋白的表达及其诊断价值评估

Objective To assess the value of thymocyte selection-associated high mobility group box (TOX) protein in the diagnosis of mycosis fungoides (MF) . Methods Totally, 63 paraffin-embedded tissue specimens were collected from Department of Pathology, West China Hospital, Sichuan University between 2003 and 2016, including 30 specimens of suspected MF, 23 specimens of confirmed MF and 10 specimens of benign inflammatory dermatoses. Immunohistochemical staining was performed to compare the expression of TOX among groups. Results Twenty-six (86.7%) suspected MF specimens were positive for TOX, 20 (87%) confirmed MF specimens, and 3 (30%) benign inflammatory dermatosis specimens were positive for TOX. The positive rate of TOX protein was significantly higher in the suspected MF group and MF group than in the benign inflammatory dermatosis group (both P<0.05) . Conclusions TOX protein was expressed to different extents in the cases of suspected or confirmed MF, and its positive rate was markedly higher in the suspected or confirmed MF group than in the benign inflammatory dermatosis group. TOX protein may act as one of molecular markers for MF. Key words: Lymphoma, T-cell; Diagnosis; Mycosis fungoides; Thymocyte selection-associated high mobility group box protein

Thymocyte selection-associated HMG-box 'thymocyte selection-associated HMG-box' in mycosis fungoides: should it be mandatory in diagnosis?

Objective To study the immunohistochemical expression of thymocyte selection-associated HMG-box (TOX) as a diagnostic marker in mycosis fungoides (MF). Background MF is the most common type of cutaneous T-cell lymphoma. Differentiation of MF from benign inflammatory dermatoses is important to ensure proper management. TOX is a critical regulator of early T-cell development that is considered as a useful marker for MF diagnosis and prognosis. Patients and methods This study was carried out on 32 skin biopsies, 20 MF cases, and 12 benign inflammatory dermatosis. The diagnosis was established after clinicopathologic correlation immunohistochemical (IHC) was done in MF cases and benign inflammatory dermatosis for TOX. This was a cross-sectional analytical study. Results TOX expression showed significant positive expression in MF cases compared with benign inflammatory dermatoses, with 80% sensitivity and 83% specificity. Also, TOX positivity increased with the progression of the disease in MF cases. There was a significant difference between MF and inflammatory groups as regards TOX expression which was in favor of the malignant group (P = 0.001). Conclusion TOX may have a potential role as a molecular diagnostic marker for MF and overexpression of it correlates with increased risk of disease progression and poor prognosis.

ARE ANTIBIOTICS OF ANY USE IN THE MANAGEMENT OF GRANULOMA ANNULARE IN CHILDREN?

Background:Granuloma annulare (GA) is a benign inflammatory dermatosis of unknown cause, of which generalised granuloma annulare (GGA) is a subtype that tends to be resistant to treatment. Various antibiotics have been used to treat GGA, the most recent being combination therapy with rifampicin, ofloxacin and minocycline (ROM). This study aims to explore the efficacy of antibiotics in treating GGA, and whether antibiotics may be useful in children with GGA.Materials and Methods:A systematic review of literature published from 1947 to 2017 was undertaken in order to evaluate the use of antibiotics in treating GGA. Data on characteristics of children with GGA were extracted and eligible studies were then qualitatively analysed.Results:Seven hundred and ninety (790) potential studies were identified, of which 16 were eligible for inclusion in the final analysis. Of these 16 studies, majority were case studies (n=9, 56.3%), with 2 case series (12.5%), 2 retrospective studies (12.5%) and 3 open-label prospective studies (18.8%). Main antibiotic treatments reported were either monthly combination therapy of rifampicin, ofloxacin and minocycline (ROM), or monotherapy with dapsone or doxycycline. Out of a total of 158 patients with GA, 72 patients (45.6%) were treated with antibiotics. Of the 72, 48.6% (n=35) of these patients had GGA while 4 were children; two with GA (2 with GGA), all of whom were treated with dapsone.Conclusion:There is paucity of evidence to support the use of antibiotics in the treatment of GGA in children. Although ROM has shown promising results in adults, more studies are needed to validate these findings in children.

The Ectopic Expression of Meiosis Regulatory Genes in Cutaneous T-Cell Lymphomas (CTCL).

Cancer testis (CT) antigens, under normal circumstances are uniquely expressed in testicular germ cells. Recent research has shown that meiosis-specific CT (meiCT) antigens are ectopically expressed in cutaneous T-cell lymphoma (CTCL) and may contribute to increased genomic instability. The aberrant activation of meiosis genes in a mitotic cell is now recognized as a distinctive process, “meiomitosis.” We have previously demonstrated the ectopic expression of several meiCT antigens in nine patient-derived CTCL cell lines and in expanded peripheral T lymphocytes isolated from Sézary Syndrome patients. In this study we analyzed the transcriptional expression of meiCT genes in Sézary Syndrome patients and healthy controls using publicly-available RNA sequencing (RNA-Seq) data. We corroborated our in silico analysis by examining the expression of 5 meiCT proteins in formalin-fixed, paraffin-embedded (FFPE) lesional samples from CTCL patients. Our results show significant differential gene expression of STAG3, SGO2, SYCP3, and DMC1 in a cohort of Sézary Syndrome patients when compared to healthy controls. Additionally, our study demonstrates a heterogenous expression of meiCT genes involved in initiation (STRA8), sister chromatin cohesion (STAG3, SGO2), homologous chromosome synapsis (SYCP3) and homologous recombination (DMC1) in atypical lymphocytes in FFPE samples. Our results further confirm the ectopic expression of meiCT genes in CTCL which indicates that CTCL malignant cells likely undergo the process of cancer meiomitosis, as opposed to a typical mitotic division. The ectopic expression of meiCT genes together with investigations into the functional mechanisms of cancer meiomitosis will help provide a foundation to develop novel diagnostic tests to distinguish CTCL from benign inflammatory dermatoses and may enable us to develop additional targeted therapies for patients with this malignancy.

Mycosis fungoides with spongiosis: A potential diagnostic pitfall.

Mycosis fungoides (MF) is characterized by epidermotropic atypical lymphocytes in the absence of spongiosis. However, we describe an unusual presentation of MF with spongiosis, mimicking benign inflammatory dermatoses and highlight the importance of pathologic interpretation for diagnostic confirmation. A cross-sectional study of consecutive patients diagnosed with MF with spongiosis was conducted. The clinical, histopathologic, immunophenotypic, and molecular genetic features of cases were reviewed. We identified nine cases of MF (age range 34-82 years; mean 75 years), with an initial diagnosis of dermatitis (6/9), psoriasis (4/9), or other inflammatory dermatoses (2/9). Pruritus, pain, and blisters were common clinical manifestations. The most common areas of involvement were the extremities (8/9). Epidermotropism with spongiosis was a central histopathological feature in all cases. These cases highlight prominent spongiosis in MF and overlap with common benign inflammatory dermatoses. We present these cases to show the diagnostic pitfalls associated with spongiotic presentations of MF. Dermatitis, psoriasis, and other inflammatory skin conditions not responsive to standard therapy warrant further work-up including biopsy to rule out MF. Multiple skin biopsies and review by a dermatopathologist with expertise in the diagnosis of cutaneous lymphoma is highly recommended.

Thymocyte selection-associated high-mobility group box as a potential diagnostic marker differentiating hypopigmented mycosis fungoides from early vitiligo: A pilot study.

Hypopigmented mycosis fungoides is a rare variant of mycosis fungoides that may mimic many benign inflammatory hypopigmented dermatoses, and as yet there is no identified marker to differentiate between them. The aim of this study was to study the expression of thymocyte selection-associated high-mobility group box (TOX) in hypopigmented mycosis fungoides and one of its inflammatory mimickers (early active vitiligo) to assess its potential as a differentiating diagnostic marker. A case-control study was done using immunohistochemical analysis of TOX expression in 15 patients with hypopigmented mycosis fungoides and 15 patients with early active vitiligo. Immunohistochemical analysis was done via a semi-quantitative method and an image analysis method. Hypopigmented mycosis fungoides showed a statistically significant higher expression of TOX than early active vitiligo. The expression of TOX was positive in a majority of hypopigmented mycosis fungoides cases (14 cases, 93.3%), while only one case (6.7%) of vitiligo was weakly positive. TOX also displayed 93.3% sensitivity and specificity, with a cut-off value of 1.5. This was a pilot study testing hypopigmented mycosis fungoides against only a single benign inflammatory mimicker (early vitiligo). Other benign mimickers were not included. Our findings showed that TOX expression can differentiate hypopigmented mycosis fungoides from early active vitiligo which is one of its benign inflammatory mimickers, with a high degree of sensitivity and specificity.

Disseminated subcutaneous granuloma annulare in adult

Granuloma annulare (GA) is a common benign inflammatory dermatosis of unknown cause. The subcutaneous form of GA also known as pseudorheumatoid nodule is a relatively uncommon entity, more so in the adult age. We came across a middle-aged female with multiple or disseminated lesions of subcutaneous GA located at an unusual location such as the volar aspect of palms beside the relatively common sites such as elbow and forearm.

Experience with fractional photothermolysis in the therapy of gra-nuloma annulare

Granuloma annulare is a benign inflammatory dermatosis of unknown etiology, which is characterized by the development of flesh-colored or red papules often arranged in rings on the skin. Currently there are no effective treatments for granuloma annulare. Topical and intradermal applications of glucocorticosteroids produce a short-term and insufficient therapeutic effect. The method cannot be used in extensive rashes. Fractional photothermolysis is a physical method for ablative exposure of tissues to an erbium laser via their local heating with light energy in certain areas. To investigate the efficiency of fractional photothermolysis in the therapy of patients with granuloma annulare. Twenty-eight patients diagnosed with granuloma annulare were followed up. All the patients were treated with fractional Fotona Fidelis XS erbium laser at a wavelength of 2940 nm using a FS01 maniple. The treatment cycle consisted of 5 sessions. After the treatment, the GASI index was decreased by 50, 75, and 100% in 5 (17.9%), 15 (53.6%), and 8 (28.6%) patients, respectively. The median GASI index was decreased by a total of 2.8 times (p<0.05). The study showed the high efficiency of fractional photothermolysis in the treatment of patients with granuloma annulare. This method can be recommended for the treatment of common forms of granuloma annulare.

Targeting Phosphorylation of p21-activated Kinase 1 at Thr423 Induces Cell Cycle Arrest and Apoptosis in Cutaneous T-cell Lymphoma Cells.

Cutaneous T-cell lymphoma (CTCL) represents a rare group of extranodal T-cell lymphoproliferative diseases. Due to poor clinical outcome of CTCL, there is an urgent need for new and improved therapies. A small molecule, IPA-3, which inhibits p21-activated kinase 1 (PAK1), has shown therapeutic potential in various types of malignancies. In the present study, the anti-tumor effect of IPA-3 and its underlying molecular mechanism was evaluated. High expression of phosphorylated-PAK1 (pho-PAK1) was seen in CTCL lesional skin compared to benign inflammatory dermatoses. IPA-3 could significantly inhibit the proliferation of 3 CTCL lines in a dose- and time-dependent manner. The percentage of apoptotic cells was higher in the treatment group. Further, IPA-3 treatment caused increased EGR1 protein levels and decreased apoptosis-related BCL-2 and pho-BAD protein levels. In summary, inhibition of pho-PAK1 has significant anti-tumor effects in CTCL cells and it can be explored as a future therapeutic option.

Mycosis fungoides progression could be regulated by microRNAs

Differentiating early mycosis fungoides (MF) from inflammatory dermatitis is a challenge. We compare the differential expression profile of early-stage MF samples and benign inflammatory dermatoses using microRNA (miRNA) arrays. 114 miRNAs were found to be dysregulated between these entities. The seven most differentially expressed miRNAs between these two conditions were further analyzed using RT-PCR in two series comprising 38 samples of early MFs and 18 samples of inflammatory dermatitis. A series of 51 paraffin-embedded samples belonging to paired stages of 16 MF patients was also analyzed. MiRNAs 26a, 222, 181a and 146a were differentially expressed between tumoral and inflammatory conditions. Two of these miRNAs (miRNA-181a and miRNA-146a) were significantly deregulated between early and advanced MF stages. Bioinformatic analysis showed FOXP3 expression to be regulated by these miRNAs. Immunohistochemistry revealed the level of FOXP3 expression to be lower in tumoral MFs than in plaque lesions in paraffin-embedded tissue. A functional study confirmed that both miRNAs diminished FOXP3 expression when overexpressed in CTCL cells. The data presented here suggest that the analysis of a restricted number of miRNAs (26a, 222, 181a and 146a) could be sufficient to differentiate tumoral from reactive conditions. Moreover, these miRNAs seem to be involved in MF progression.

Loss of 5-Hydroxymethylcytosine Is an Epigenetic Biomarker in Cutaneous T-CellLymphoma.

DNA hydroxymethylation at the 5 position of cytosine (5-hmC) is a product of the TET family of DNA hydroxylases. Accumulating evidence shows that loss of 5-hmC is critical for various biological and pathological processes. However, its level in cutaneous T-cell lymphoma (CTCL) remains largely unknown. Here, we report that the loss of 5-hmC is an epigenetic hallmark of CTCL, with diagnostic and prognostic implications. Immunohistochemistry staining on 90 mycosis fungoides (MF) samples showed a significant decrease of 5-hmC staining in CD4+ T cells in patch and tumor stages, especially in MF with large cell transformation, compared with benign inflammatory dermatoses. The 5-hmC staining level decreased with disease progression and showed remarkable loss in the large cells of large cell transformed MF samples, regardless of the CD30 positivity. Furthermore, 5-hmC decrease was correlated to poor overall survival in our patient cohort. Pharmacological augments of global 5-hmC with l-ascorbic acid in CTCL cell lines led to remarkable 5-hmC accumulation and promoted apoptosis in CTCL cell lines, as well as in patient-derived CTCL cells. In conclusion, 5-hmC is an epigenetic mark of predictive value in MF prognosis. Restoration of 5-hmC levels in MF may serve as a therapeutic regimen in CTCL.

197 Loss of 5-hydroxymethylcytosine is an epigenetic hallmark of disease progression in cutaneous T cell lymphoma

DNA hydroxymethylation at the 5 position of cytosine (5-hmC) is a product of the ten-eleven translocation (TET) family of DNA hydroxylases. Accumulating pieces of evidence showed that loss of 5-hmC is critical for various biological and pathological processes. However, its expression and function in cutaneous T cell lymphoma remain largely unknown. Here, with a large cohort of patients, we report that loss of 5-hmC is an epigenetic hallmark of cutaneous T cell lymphoma, with diagnostic and prognostic implications. Immunohistochemistry staining on 91 mycosis fungoides (MF) cases display a significant decrease of 5-hmC staining in CD4+ T cells, compared to benign inflammatory dermatoses, including lupus erythematosus (N=15), lichen planus (N=15), and psoriasis (N=12). 5-hmC staining level is further decreased with disease progression and demonstrates remarkable loss of staining in the large cells of large cell transformed MF cases, regardless of the CD30 positivity. Furthermore, 5-hmC decreases are correlated with poorer overall survival in our patient cohort. Compared to healthy CD4+ T cells, 5-hmC levels also decreased in 9 CTCL cell lines. Pharmacological augment of global 5hmC with L-ascorbic acid [L-AA] and 2-phospho-L-ascorbic acid (P-AA) in CTCL cell lines lead to a remarkable 5-hmC accumulation and induce specific apoptosis in CTCL cell lines, as well as primary CTCL cells. In conclusion, 5-hmC is an epigenetic marker of disease progression in MF. Reversing 5-hmC levels in MF may serve as a novel therapeutic regimen in cutaneous T cell lymphoma.

MicroRNA Signatures in Diagnosis and Prognosis of Cutaneous T-Cell Lymphoma

Cutaneous T cell lymphoma (CTCL) can have clinical and histological features resembling benign inflammatory dermatosis and can be difficult to diagnose. Very limited biomarkers are available for CTCL prognosis. We aimed to identify microRNA (miR) signatures to facilitate diagnostic and prognostic evaluations of CTCL. Across-platform miR microarray identified 10 miRs that were differentially expressed between CTCL and benign inflammatory dermatosis patients. Subsequent reverse transcription polymerase chain reaction validation was used to generate a 5-miR-based diagnosing classifier, which showed high diagnostic accuracy in CTCL (area under the curve= 0.985 and 0.956 for training and testing set, respectively). Association between miR expressions and patient prognosis was studied. miR-155 and miR-200b were significantly associated with overall survival in CTCL patients, outperformed Ki-67. miR expressions were combined with Ki-67 to create a classifier for 5-year overall survival in CTCL patients. Our work provided miR signatures to facilitate CTCL diagnosis and prognosis with satisfying accuracy.

PAK1 overexpression promotes cell proliferation in cutaneous T cell lymphoma via suppression of PUMA and p21

BackgroundCutaneous T cell lymphoma (CTCL) comprises a heterogeneous group of skin-homing T cell tumors. The small guanosine triphosphate effector p21-activated kinase 1 (PAK1) plays an important role in many fundamental cellular functions, including cell motility, proliferation, and apoptosis. The expression of PAK1 is up-regulated in several types of human cancers. However, little is known about the role of PAK1 in the pathogenesis of CTCL. ObjectiveThe aim of this study was to evaluate the expression pattern and underlying mechanism of PAK1 in CTCL. MethodsQuantitative real-time polymerase chain reaction(qRT-PCR) was used to detect PAK1 mRNA expression in the peripheral blood mononuclear cells (PBMCs) of patients with CTCL. The expression of PAK1 protein in CTCL tumor tissues was determined by immunohistochemistry. CTCL cell lines were treated with a small molecule inhibitor of PAK1, p21-activated kinase inhibitor III (IPA3), at concentrations of 2, 3.5 and 5 μM for 24 h. Hut 78 and HH CTCL cells were transfected with lentiviral-based PAK1 gene knockdown vectors. We determined the effects of PAK1 knockdown on cell proliferation and apoptosis in CTCL cells by MTS assay and flow cytometry. Animal experiments were performed to investigate the effects of PAK1 knockdown on the growth of tumors in vivo. Transcriptomic sequencing was performed to detect the direct downstream targets of PAK1 silencing. Reverse transcription polymerase chain reaction and western blot analysis were applied to verify the results of the transcriptomic analysis. ResultsWe detected PAK1 overexpression in PBMCs and skin lesions from patients with CTCL compared with benign inflammatory dermatoses (BID). Knockdown of PAK1 inhibited cell proliferation and promoted spontaneous apoptosis. In addition, the inhibitory effect of IPA3 was validated in the CTCL cell lines. Additionally, mice injected with PAK1-silenced cells presented with a decreased rate of tumor growth compared with the control groups. Moreover, the mRNA and protein expression of PUMA (BBC3) and p21 (CDKN1A) were increased in PAK1-silenced Hut 78 and HH cells. ConclusionsOur data indicated that PAK1 is upregulated in CTCL. PAK1 silencing induced apoptosis and inhibited cell growth by stimulating the expression of PUMA and p21. Thus, PAK1 may be a potential tumor marker and therapeutic target of CTCL.

C-CBL E3 Ubiquitin Ligase Expression Increases Across the Spectrum of Benign and Malignant T-Cell Skin Diseases.

Prolonged survival of lesional T cells plays a central role in the pathogenesis of T-cell-mediated dermatoses. We have recently shown that the ubiquitin ligase c-CBL is highly expressed in cutaneous T-cell lymphoma (CTCL) and that its knockdown increases activation-induced cell death, a key pathway for T-cell apoptosis. Here, we extend our work on c-CBL expression in malignant T cells to their nonneoplastic counterparts in benign inflammatory dermatoses. Immunohistochemical staining with anti-c-CBL antibody was performed on lesional biopsies from a total of 65 patients with atopic dermatitis, allergic contact dermatitis, pityriasis rosea, psoriasis vulgaris, lichen planus, mycosis fungoides (MF)/Sézary syndrome (SS) as well as on tonsil tissue from 5 individuals and on 5 human CTCL cell lines. Protein levels were measured in situ using multispectral image analysis, a quantitative method that is ×5 more sensitive than standard immunohistology for antigen detection. There was a significant (P < 0.05) and progressive increase of mean c-CBL expression across the spectrum of inflammatory dermatoses (2-fold), MF/SS (3-fold), and lymphoma cell lines (4-fold) as compared with tonsillar T lymphocytes. A subset of MF/SS cases expressed mean c-CBL levels above the ranges observed in inflammatory dermatoses. Given our prior finding that c-CBL inhibits activation-induced cell death, c-CBL might play a role in the pathogenesis of inflammatory dermatoses and CTCL.

Gene expression analysis in Cutaneous T-Cell Lymphomas (CTCL) highlights disease heterogeneity and potential diagnostic and prognostic indicators

ABSTRACTCutaneous T-Cell Lymphomas (CTCL) are rare, but potentially devastating malignancies, whose pathogenesis remains poorly elucidated. Unfortunately, currently it is not possible to predict based on the available criteria in which patients the cancer will progress and which patients will experience an indolent disease course. Furthermore, at early stages this malignancy often masquerades as psoriasis, chronic eczema or other benign inflammatory dermatoses. As a result, it takes on average 6 y to diagnose this lymphoma since its initial presentation. In this study, we performed transcription expression profiling using TruSeq targeted RNA gene expression on 181 fresh and formalin-fixed and paraffin-embedded (FFPE) skin samples from CTCL patients and patients affected by benign inflammatory dermatoses that often mimic CTCL clinically and on histology (e.g., psoriasis, chronic eczema, etc.) We also analyzed multiple longitudinal biopsies that were obtained from the same patients over time. Our results underscore significant molecular heterogeneity with respect to gene expression between different patients and even within the same patients over time. Our study also confirmed TOX, FYB, LEF1, CCR4, ITK, EED, POU2AF, IL26, STAT5, BLK, GTSF1 and PSORS1C2 genes as being differentially expressed between CTCL and benign skin biopsies. In addition, we found that differential expression for a subset of these markers (e.g., TOX, FYB, GTSF1 and CCR4) may be useful in prognosticating this disease. This research, combined with other molecular analyses, prepares the foundation for the development of personalized molecular approach toward diagnosis and management of CTCL.

Cutaneous Extranodal Natural Killer/T-Cell Lymphomas Histopathologically Mimicking Benign Inflammatory Disease.

Few studies have evaluated the histopathological features of cutaneous extranodal NK/T-cell lymphoma (ENKTL). The authors' study aims to describe cases of cutaneous ENKTL that histopathologically mimic benign inflammatory dermatosis. The authors searched the database of Asan Medical Center to identify cases of cutaneous ENKTL that were confirmed by skin biopsy between January 1998 and December 2014. The authors included cases that were initially diagnosed as benign inflammatory disorders on the histopathological examination, but finally diagnosed as cutaneous ENKTL on further evaluation. This study included 10 cases of cutaneous ENKTL. Six cases demonstrated nonspecific perivascular cellular infiltration, 2 cases demonstrated lupus erythematosus-like histological features, 1 case demonstrated psoriasiform lichenoid reaction, and 1 case demonstrated vasculitis-like features on histopathological examination. All cases were positive for CD56 and Epstein-Barr virus in situ hybridization. Perivascular infiltrations throughout the superficial and deep dermis with vasculopathy and panniculitic infiltration were common histopathological findings. The clinical features included 7 cases of erythematous to purpuric patches, 2 cases of facial swelling, and 1 case of cellulitis-like swelling. In conclusion, cutaneous ENKTL can histopathologically mimic benign inflammatory dermatosis. Cutaneous ENKTL should be suspected when histopathology shows perivascular dermal infiltration with vasculopathy and panniculitic cellular infiltration.

Generalised Granuloma Annulare-Uncommon in Clinical Practice

Generalised granuloma annulare is a benign inflammatory dermatosis characterized by dermal papules and annular plaques. It is often clinically confused with other dermatoses particular superficial fungal infection. A man of 50 years came with multiple erythematous, mildly pruritic, firm papules and annular skin lesion over the extremites and back of trunk for the last two years. He was treated with an oral antifungal for several months under diagnosis of tinea corporis without remission. The diagnosis of Generalised Granuloma Annulare was made based on skin biopsy and histopathological examination. Oral Acitretin and topical tacrolimus (0.1%) were administered and after 1 month of follow up period the lesion were started to regress. Complete remission was found after 3 months treatment.&#x0D; CBMJ 2016 July: Vol. 05 No. 02 P: 39-42

TOX expression in cutaneous T-cell lymphomas: an adjunctive diagnostic marker that is not tumour specific and not restricted to the CD4(+) CD8(-) phenotype.

TOX (thymocyte selection-associated high-mobility group box) was shown to be aberrantly expressed in mycosis fungoides (MF) and Sézary syndrome (SS) and is suggested to have additional diagnostic value. However, data on expression in other types of cutaneous T-cell lymphoma (CTCL) are scarce and it is unknown whether TOX is expressed only by MF with a CD4(+) CD8(-) phenotype. To investigate TOX expression in various types of CTCL with different T-cell phenotypes. Immunohistochemical expression of TOX was evaluated on 153 skin biopsies of 132 patients with CTCL and 60 patients with benign inflammatory dermatoses (BIDs). TOX was expressed by >50% of the neoplastic T cells in 49 of 59 patients (83%) with MF and in 19 of 22 patients (86%) with SS. The TOX(+) cases of MF included 34 of 35 cases (97%) with a CD4(+) CD8(-) phenotype, but also five of eight cases (63%) with a CD4(-) CD8(+) phenotype and 10 of 16 cases (63%) with a CD4(-) CD8(-) phenotype. TOX expression in other types of CTCL was common but showed variable intensity. Although only one of 60 patients (2%) with a BID expressed TOX in >50% of the skin-infiltrating T cells, some caution is warranted, as the majority of BIDs had TOX(+) T cells varying between 11% and 50%. TOX expression is not tumour specific, is not restricted to CTCL with a CD4(+) CD8(-) phenotype, and, on its own, is insufficient for diagnosis of CTCL. However, it may have an adjunctive diagnostic role in conjunction with other clinical and histological data.

TOX expression and role in CTCL.

Cutaneous T-cell lymphomas (CTCL) are skin malignancies including mycosis fungoides (MF) and CD30(+) lymphoproliferative disorders (LPD). In early disease, CTCL can be difficult to diagnose, especially in MF for which there is no reliable diagnostic marker. MF/CTCL have increased expression of thymocyte selection-associated HMG box protein (TOX). Although TOX has been proposed to be a diagnostic marker for MF, further validation studies are needed. Moreover, it is unclear what drives TOX expression or its role in MF/CTCL. We hypothesize evaluation of TOX levels across a spectrum of CTCL, including MF precursor (large plaque parapsoriasis, LPP), will help elucidate the implications of altered TOX expression. TOX staining was performed in MF, CD30(+) LPD, LPP as well as benign inflammatory dermatoses (BID) and normal skin (NS). CTCL cell lines were utilized to evaluate the regulation of TOX. Positive TOX expression was identified in 73.6% of MF cases and in 31.6% of BID/NS. TOX had a positive predictive value (PPV) for MF of 86.7% and a negative predictive value (NPV) of 48.1%. TOX expression in MF was detected more commonly in Black patients (P = 0.015) and less commonly in transformed MF (P = 0.045). LPP had positive TOX staining in 70.0%. In CTCL cells, GATA3 knockdown decreased TOX mRNA and protein expression. TOX expression also decreased in the presence of CTCL therapeutics. Our data indicate that TOX is useful as a diagnostic marker in MF. Moreover, TOX expression was evident in LPP, indicating it may have a previously unappreciated role in the development of MF. Finally, our data suggest that GATA3 regulates TOX, revealing insight into TOX regulation.