Conventional Mycosis Fungoides Research Articles

Detecting T-cell receptor clonality in patients with severe atopic dermatitis refractory to dupilumab.

Trials and real-life studies demonstrated clinically meaningful improvements of disease activity in the majority of patients with moderate to severe atopic dermatitis (AD) treated with the anti-IL-4RA-antibody dupilumab. However, misdiagnosis or confounding skin diseases in particular cutaneous T-cell lymphoma (CTCL) may lead to inadequate response. To investigate the clinical and pathological features of patients with AD who showed insufficient response to dupilumab. We reviewed the medical records of 371 patients treated with dupilumab for severe AD. Insufficient response was defined as failure to achieve an improvement of the eczema area severity index (EASI) of at least 50% (EASI-50) at Week 16 and of 75% (EASI-75) at Week 52. Among 46 patients with insufficient response, 35 patients consented to a re-evaluation including a full physical exam, biopsies and laboratory assessments including immunohistochemistry and T-cell receptor gene rearrangement analysis to differentiate CTCL. Of the 371 patients treated with dupilumab, 46 (12.3%) patients showed insufficient response to dupilumab. Of these, 35 underwent further evaluation, and 19 (54.2% of inadequate responders) were finally diagnosed with mycosis fungoides (MF). In these patients, transition to or addition of conventional MF treatment led to clinical improvements. Insufficient response to dupilumab treatment may help uncover early MF on an existing AD background.

Dermoscopic Findings of Pilotropic Mycosis Fungoid: A Rare Variant

Pilotropic mycosis fungoid (PMF) is a rare variant of mycosis fungoides (MF) with distinctive clinicopathological features, accounting for 1 to 5%. It is characterized by a broad spectrum of clinical features and has a more aggressive clinical course than conventional MF [1]. At the onset of its progression, pilotropic mycosis fongoides is sometimes difficult to distinguish from classical mycosis fongoides with follicular involvement.

Bio-P-04 - Single-cell RNA sequencing reveals markers of disease progression in primary cutaneous T-cell lymphoma

<h3>Background:</h3> In early-stage mycosis fungoides (MF), the most common primary cutaneous T-cell lymphoma, limited skin involvement with patches and plaques is associated with a favorable prognosis. Nevertheless, approximately 20–30% of cases progress to tumors or erythroderma, resulting in poor outcome. At present, factors contributing to this switch from indolent to aggressive disease are only insufficiently understood. <h3>Methods:</h3> In patients with advanced-stage MF, we compared patches with longstanding history to newly developed plaques and tumors by using single-cell RNA sequencing, in order to characterize markers of lesion progression. <h3>Results:</h3> Despite considerable inter-individual variability, lesion progression was uniformly associated with downregulation of a combination of tissue residency markers, heat shock proteins, tumor suppressor genes and chemokine receptors in the malignant clone. By contrast, collateral benign infiltrating immune cells within the lesions did not show consistent changes at the mRNA level. This phenomenon was not only found in conventional TCR-αβ MF, but also in a case of TCR-γδ MF, suggesting a mechanism across MF subtypes. Markers of disease progression were reverted upon successful topical treatment with chlormethine. <h3>Conclusions:</h3> Our data reveal a specific panel of biomarkers that might be used for monitoring MF disease progression. Altered expression of these genes may underlie the switch in clinical phenotype observed in advanced-stage MF.

Single-cell RNA sequencing reveals markers of disease progression in primary cutaneous T-cell lymphoma

BackgroundIn early-stage mycosis fungoides (MF), the most common primary cutaneous T-cell lymphoma, limited skin involvement with patches and plaques is associated with a favorable prognosis. Nevertheless, approximately 20–30% of cases progress to tumors or erythroderma, resulting in poor outcome. At present, factors contributing to this switch from indolent to aggressive disease are only insufficiently understood.MethodsIn patients with advanced-stage MF, we compared patches with longstanding history to newly developed plaques and tumors by using single-cell RNA sequencing, and compared results with early-stage MF as well as nonlesional MF and healthy control skin.ResultsDespite considerable inter-individual variability, lesion progression was uniformly associated with downregulation of the tissue residency markers CXCR4 and CD69, the heat shock protein HSPA1A, the tumor suppressors and immunoregulatory mediators ZFP36 and TXNIP, and the interleukin 7 receptor (IL7R) within the malignant clone, but not in benign T cells. This phenomenon was not only found in conventional TCR-αβ MF, but also in a case of TCR-γδ MF, suggesting a common mechanism across MF subtypes. Conversely, malignant cells in clinically unaffected skin from MF patients showed upregulation of these markers.ConclusionsOur data reveal a specific panel of biomarkers that might be used for monitoring MF disease progression. Altered expression of these genes may underlie the switch in clinical phenotype observed in advanced-stage MF.

Association of a Proposed New Staging System for Folliculotropic Mycosis Fungoides With Prognostic Variables in a US Cohort

A new cutaneous staging system for folliculotropic mycosis fungoides (FMF) has been purported to better estimate survival compared with the staging system for conventional mycosis fungoides. To analyze predictive variables associated with survival and evaluate the effectiveness of the newly proposed staging system for estimating overall survival and disease-specific survival (DSS) in a US cohort. This cohort study assessed 195 patients with FMF in the dermatopathology database of the University of California, San Francisco from January 1, 1990, to April 31, 2012, for eligibility. A total of 153 patients were excluded for the following reasons: (1) alternative diagnoses were favored ranging from benign dermatitides to other forms of cutaneous lymphoma; (2) technical problems with slides; and (3) lack of follow-up information. Data were analyzed from January 1, 2018, to August 31, 2020. Kaplan-Meier curves were used to estimate overall survival and DSS for the entire cohort. Possible predictive variables associated with survival were evaluated using Cox proportional hazards regression modeling. Each variable was examined separately, followed by a multiple-variable model. Kaplan-Meier curves were used to estimate overall survival and DSS by subdividing the cohort into early- and advanced-stage cutaneous disease. Forty-two patients were included in the analysis (mean age at diagnosis, 55 [range, 8-89] years; 31 men [74%]). For the entire cohort, the estimated 5-year overall survival rate was 89% (95% CI, 79%-99%); 10-year rate, 78% (95% CI, 63%-92%); and 15-year rate, 58% (95% CI, 31%-85%). Estimated 5- and 10-year DSS rates were 89% (95% CI, 79%-99%); 15-year rate, 80% (95% CI, 61%-99%). For overall survival in the multiple-variable Cox proportional hazards regression model, only age was statistically significant (hazard ratio [HR] per 10-year age increase, 3.1; 95% CI, 1.4-7.2; P = .008), whereas for DSS, only cutaneous disease was statistically significant (HR, 11.4; 95% CI, 1.3-103.0; P = .03). When stage stratified, the 5-year estimated overall survival rate for early-stage disease was 96% (95% CI, 89%-103%); 10-year rate, 82% (95% CI, 65%-98%); and 15-year rate, 65% (95% CI, 33%-97%). For advanced-stage disease, the estimated 5- and 10-year overall survival rates were 70% (95% CI, 41%-98%); the 15-year rate, 53% (95% CI, 16%-89%). For early-stage cutaneous disease, the estimated 5-, 10- and 15-year DSS rates were all 96% (95% CI, 89%-103%). For advanced-stage cutaneous disease, the estimated 5- and 10-year DSS rates were 70% (95% CI, 41%-98%); the 15-year rate, 53% (95% CI, 16%-89%). Cox proportional hazards regression modeling demonstrated cutaneous stage to be the only statistically significant predictive variable associated with DSS. Subdividing FMF into early and advanced cutaneous stages was associated with effective estimation of survival in this cohort. Thus, findings suggest that FMF is a heterogeneous disease with early and advanced cutaneous stages; that the new staging system is effective in estimating survival in a US cohort; and that the poor prognosis initially associated with FMF only applies to the advanced cutaneous stage.

Cicatricial Alopecia Related to Folliculotropic Mycosis Fungoides

Folliculotropic mycosis fungoides (FMF) is a particular subtype of mycosis fungoides (MF), characterized by an infiltration of neoplastic CD4+ T cells in the epidermis which can spread to all follicular structures, sebaceous glands, sweat glands and hair follicles. Clinically, FMF can exhibit various cutaneous symptoms. However, these symptoms often occur on the scalp, face and neck, which are rarely affected by conventional MF. We report cicatricial alopecia in a patient with FMF as alopecia lymphomatica. This peculiar symptom should be kept in mind as a critical differential diagnosis of scarring alopecia, leading to further investigation. Thus, an early diagnosis of FMF may be obtained.

Unilesional mycosis fungoides is associated with increased expression of microRNA-17~92 and T helper 1 skewing.

The molecular basis of unilesional mycosis fungoides (MF), characterized by a solitary lesion that is clinicopathologically indistinguishable from multifocal patch or plaque MF (early MF), is unknown. To investigate the microRNA profile in unilesional MF distinguishing it from early MF. Biopsy samples of unilesional MF and early MF were evaluated with the Affymetrix microRNA array, with further comparison with inflammatory dermatosis, using quantitative polymerase chain reaction. NanoString technology was applied to analyse the gene expression of T helper (Th)1 immune markers, and immunohistochemistry was used to evaluate CXCR3 and GATA-binding protein 3 (GATA3) markers for Th1 and Th2 cells, respectively. Unilesional MF had a significantly higher level of expression of all members of the microRNA miR-17~92 cluster than early MF. Specifically, unilesional MF had a higher miR-17 level than early MF and inflammatory dermatoses. There was downregulation of the expression of phosphatase and tensin homolog (PTEN) and CREB1, known targets of miR-17~92 members; higher gene expression of interleukin-2 and interferon-γ; and a statistically lower average percentage of GATA3+ dermal cells (6·7% vs. 42·3%), were detected in unilesional MF compared with early MF. High immunoreactivity of CXCR3 was noted in both unilesional and early MF. Unilesional MF exhibits a microRNA profile distinct from that of conventional early MF, with a higher level of miR-17~92 members along with Th1 skewing. These findings suggest a robust reactive T-cell immune response in unilesional MF and might account for the localized nature of this disease.

Interstitial Mycosis Fungoides: A Clinicopathologic Study of 21 Patients.

Interstitial mycosis fungoides (IMF) is a rare histopathologic variant of mycosis fungoides (MF) that may mimic other inflammatory dermatoses, mainly interstitial granuloma annulare, inflammatory morphea, and interstitial granulomatous dermatitis. Only small series and sporadic case reports of IMF have been described in the literature. We reviewed 27 specimens from 21 patients with IMF (M:F=11:10, median age 60) to better characterize clinical, histopathologic, and immunohistochemical features of this disease. Most patients presented clinically with patches and/or plaques. Conventional MF was documented before, concomitant with, or after IMF in 12 patients, whereas only in 2 patients different biopsies showed exclusive features of IMF over a period of 4 and 191 months, respectively. Histology revealed in all cases variably long, linear aggregates of dermal lymphocytes splaying the collagen fibers, involving predominantly the superficial and mid-dermis (6 cases) or the entire dermis (21 cases). Immunohistochemical stainings revealed a cytotoxic phenotype in 9/18 tested cases. Variable amounts of histiocytes/macrophages were found interstitially in all tested biopsies but never represented a population larger than that of T lymphocytes. Our study shows that IMF is a peculiar variant of MF with frequent cytotoxic phenotype. This histopathologic variant in most cases represents a transient pattern in otherwise conventional MF. Accurate clinicopathologic correlation and phenotypic studies of atypical dermal interstitial lymphohistiocytic infiltrates allow to make a correct diagnosis.

Loss of melanocytes in hypopigmented mycosis fungoides: a study of 18 patients

Hypopigmentation in hypopigmented mycosis fungoides (MF) is thought to result from the action of CD8+ cells on melanocytes. Here, we investigated the immunophenotype and melanocytic markers in hypopigmented MF lesions. Specimens of hypopigmented lesions and normal skin from 18 patients with hypopigmented MF and specimens of non-hypopigmented lesions from 8 patients with classic/conventional MF were subjected to neoplastic immunophenotyping and melanocyte immunostaining with Melan-A, tyrosinase, stem cell factor receptor (CD117) and microphthalmia-associated transcription factor (MiTF). The CD8+ immunophenotype was more common in hypopigmented MF lesions (14/18) than in conventional MF lesions (1/8, p = 0.0033). There was a main effect of specimen type (hypopigmented MF lesion, hypopigmented MF normal skin, conventional MF lesion) on the number of melanocytes stained with Melan-A (median number/mm basal membrane, 1.97 vs. 4.77 vs. 5.42, respectively, p = 0.0046), tyrosinase (2.19 vs. 4.02 vs. 5.26, p = 0.0114), CD117 (4.29 vs. 7.81 vs. 5.45, p = 0.0064), and MiTF (2.75 vs. 4.43 vs. 4.98, p = 0.005). These results confirm previous findings of fewer melanocytes and CD117-positive melanocytes in hypopigmented MF and showed reduced MiTF identification, which is crucial for the function and survival of melanocytes. Thus cytotoxic CD8+ cell action may determine CD117/MiTF dysfunction, causing hypopigmentation.

19. Folliculotropic mycosis fungoides with cysts and comedones

Mycosis fungoides (MF) is the most common primary cutaneous T-cell lymphoma. Folliculotropic MF (FMF) is an uncommon variant, characterised by folliculocentric T-cell infiltrates. FMF shows a tendency towards more rapid progression than conventional MF and a relative resistance to skin targeted therapy, warranting its separation from conventional MF, which is reflected in the current WHO classification. The majority of cases of FMF present clinically with follicular papules, alopecia, mucinorrhoea and pruritis. In uncommon cases there can be an acneiform appearance. These cases show histological evidence of prominent milia, infundibular cysts and comedones. This uncommon form of an uncommon disease poses a significant diagnostic challenge, as there is close clinical and pathological mimicry of a number of benign folliculocentric inflammatory processes. We present a case of FMF with prominent follicular cysts, comedones and secondary granulomatous inflammation which was clinically and histologically mistaken for a benign process, including epidermal cyst, on two separate biopsies reported two years apart on two continents.

Clinical and Histopathological Features of Folliculotropic Mycosis Fungoides: A Norwegian Patient Series

Folliculotropic mycosis fungoides is a variant of cutaneous T-cell lymphoma with distinct clinicopathological features. We describe here the clinical presentation, pathology findings and treatment outcome in 15 Norwegian patients. All patients were diagnosed between 1997 and 2010 at Oslo University Hospital. A spectrum of skin lesions, both typical and atypical, such as leonine facies, acneiform lesions, psoriasiform plaques, purulent ulcerations and cystic milia-like lesions for mycosis fungoides, were seen. Histological examination revealed characteristic infiltration of hair follicles with neoplastic T cells associated with partial destruction of the former. A CD4+ immunophenotype of the neoplastic T cells with loss of one or more T-cell markers was demonstrated. In general, the patients were given more aggressive therapeutic regimens than those with conventional mycosis fungoides, and showed a trend towards more rapid disease progression. In conclusion, this case series confirms the distinct clinical and histological features of folliculotropic mycosis fungoides.

Coexistence of Patch Stage Mycosis Fungoides and Interstitial Granuloma Annulare in the Same Patient

Several clinical and histopathologic variants of mycosis fungoides (MF) have been well described, including the often elusive interstitial MF. Differentiation from other inflammatory disorders, such as interstitial granuloma annulare (GA) and inflammatory morphea, may be extremely difficult. We report a case of MF and GA coexisting in a 54-year-old woman who initially presented to clinic in 2000 with slightly scaly patches on the trunk and extremities, histopathologically diagnostic of MF. A second biopsy taken a few months later revealed an interstitial infiltrate that was initially interpreted as interstitial MF. Over the following 10 years, additional biopsies revealed features of conventional MF. In 2009, a new biopsy showed unequivocal features of interstitial GA. Reevaluation of the original biopsy, diagnostic of "interstitial MF," revealed that this, too, could be better classified as interstitial GA than interstitial MF. Our case illustrates that MF and interstitial GA may coexist simultaneously, thus representing a pitfall in the histopathologic diagnosis of MF. Given the similarities in clinicopathologic presentation, dermatologists and dermatopathologists should be cautious not to inadvertently misinterpret GA as interstitial MF.

Granulomatous mycosis fungoides presenting as poikiloderma

Granulomatous mycosis fungoides (MF) is a rare subtype of MF, characterized by the histological presence of a granulomatous reaction, but distinct clinical characteristics are not present. A 41-year-old healthy man presented with poikiloderma, ichthyosis and erythematous scaly plaque. Histological examination of a biopsy taken from poikilodermic skin showed a granulomatous reaction to epidermotropic atypical lymphocytes. However, in other areas there were only findings of conventional MF without granuloma. Granulomatous MF may be associated with poikiloderma.

Folliculotropic Mycosis Fungoides

To study the clinical features, therapeutic responses, and outcomes in patients with folliculotropic mycosis fungoides (FMF) and to compare our single-center experience of 43 patients with the findings from the Dutch Cutaneous Lymphoma Group. A single-center experience from the Northwestern University Multidisciplinary Cutaneous Lymphoma Group. Forty-three patients with FMF were included in the study and compared with 43 age- and stage-matched patients with classic epidermotropic mycosis fungoides (MF) with similar follow-up time. Folliculotropic mycosis fungoides showed distinct clinical features, with 37 patients having facial involvement (86%) and only 6 having lesions limited to the torso (14%). The morphologic spectrum of lesions is broad and includes erythematous papules and plaques with follicular prominence with or without alopecia; comedonal, acneiform, and cystic lesions; alopecic patches with or without scarring; and nodular and prurigolike lesions. Sixty-five percent of patients had alopecia, which in 71% of cases involved the face. Severe pruritus was seen in 68% of patients. In general, patients responded poorly to skin-directed therapy and in almost all cases required systemic agents to induce even a partial remission, including patients with early-stage disease. Overall survival was poor. Patients with early-stage disease (< or =IIA) had a 10-year survival of 82%, which took a steep drop off to 41% by 15 years. Patients with late-stage disease (> or =IIB) had an outcome similar to those patients in the control group with conventional epidermotropic MF of a similar stage. The morphologic spectrum of clinical presentation for FMF is broad and distinct from those in conventional MF. This is at least partially attributed to the ability of FMF to simulate a variety of inflammatory conditions afflicting the follicular unit. The disease course is aggressive, and many patients, including those with early disease, show a poor outcome particularly between 10 and 15 years after the initial onset of disease. Response to skin-directed therapy is poor even in early-stage disease, and our best results were seen with psoralen plus UV-A (PUVA) therapy with oral bexarotene or PUVA with interferon alfa. These findings corroborate those of the Dutch Cutaneous Lymphoma Group and further validate the classification of FMF as a distinct entity.

The Spectrum of Histopathologic and Immunohistochemical Findings in Folliculotropic Mycosis Fungoides

Since the original designation of folliculotropic mycosis fungoides (FMF) as a distinct entity, there has been an increasing appreciation of the broad clinical and histopathologic spectrum with which this disease can present. However, there have been few large histologic studies characterizing the various histopathologic patterns. In this study, we attempt to describe the histopathologic and immunohistochemical features of 47 biopsy specimens from 34 patients with FMF. We searched our lymphoma database for patients with FMF in which detailed histopathologic information and slides as well as clinical information was available for review. Additionally, immunohistochemical studies for CD4, CD8, and CD1a were performed in all cases in which the block was available. In addition to the prototypical pattern of a folliculotropic lypmphoid infiltrate with or without mucinosis, the histologic features of follicular mycosis fungoides may include a granulomatous reaction, cystic and comedonal changes, an eosinophilic folliculitis pattern and basaloid folliculolymphoid hyperplasia as well as pustular changes, interface dermatitis and an interstitial dermatitislike pattern. Unlike conventional mycosis fungoides, eosinophils and plasma cells are conspicuous within the accompanying reactive infiltrate. We have also noted an exceedingly high number of Langerhans cells within the follicular epithelium. The CD4:CD8 ratio frequently is 10:1 or greater and the follicles show abundant CD1a positive cells. FMF may present with a broad spectrum of histopathologic changes including interstitial, granulomatous, fibrotic and acneiform reactions that may lack the typical histologic attributes of a cutaneous T-cell lymphoma. Recognition of these myriad of histologic presentations can be of great diagnostic utility.

Mycosis fungoides/Sézary syndrome: report of an unusual case

Sézary syndrome (SS) is an uncommon form of cutaneous T cell lymphoma (CTCL) with a classical triad of lymphadenopathy, characteristic circulating lymphoma cells (Sézary cells) and erythrodermatous skin involvement with classical mycosis fungoides (MF)-like histological picture. A 32-year-old woman presented with this classical triad; however, her skin involvement, histologically, was in the form of folliculotropic MF, rather than the usual classical form of MF. In the vast majority of cases, the cutaneous involvement in SS resembles conventional MF, histologically. One case of CD30-positive CTCL with pilotropic MF has been reported. However, English literature does not describe any case of SS with folliculotropic MF with typical immunophenotype of SS thus far. We presume that this case represents the first report of SS with folliculotropic MF histologically, displaying the typical CD30-negative immunophenotype.

Decreased CD117 expression in hypopigmented mycosis fungoides correlates with hypomelanosis: lessons learned from vitiligo

Hypopigmented mycosis fungoides is an uncommon clinical variant of cutaneous T-cell lymphoma. We hypothesized that hypomelanosis in hypopigmented mycosis fungoides may have a similar mechanism as in vitiligo, a condition in which it is believed that alterations in expression of CD117 (stem cell factor receptor/KIT protein) on epidermal melanocytes and abnormal interactions between melanocytes and surrounding keratinocytes may play a pathogenic role. To test the hypothesis that similar mechanisms might also explain hypopigmentation in hypopigmented mycosis fungoides, skin specimens from five cases each of hypopigmented mycosis fungoides and vitiligo were studied immunohistochemically for immunophenotype of the infiltrating cells, CD117 (expressed by epidermal melanocytes), and pan melanoma cocktail of antigens (gp100, tyrosinase, and MART-1) expression; cases of conventional mycosis fungoides and normal skin were studied in parallel as controls. Our findings confirm a predominance of CD8+ neoplastic T cells in hypopigmented mycosis fungoides. Similarly, the epidermal lymphocytic infiltrate in vitiligo was also composed of CD8+ cytotoxic T cells, in contrast to an epidermal infiltrate composed of CD4+ T cells in conventional mycosis fungoides. The average number of epidermal CD117 expressing cells followed the same pattern of decreased expression in hypopigmented mycosis fungoides as in vitiligo, whereas the levels in conventional mycosis fungoides were higher, and similar to that observed in normal skin. Furthermore, a decreased number of melanocytes per high-power field of the length of the biopsy was present in hypopigmented mycosis fungoides and vitiligo, as compared with either conventional mycosis fungoides or normal skin, suggesting a correlation between decreased expression of CD117 and decreased number of melanocytes. We propose that decreased expression of CD117 and its downstream events in melanocytes may be initiated by cytotoxic effects of melanosomal-antigen-specific CD8+ neoplastic T lymphocytes, resulting in destabilization of CD117 and leading to dysfunction and/or loss of melanocytes in the epidermis of hypopigmented mycosis fungoides.

Ichthyosiform mycosis fungoides: An atypical variant of cutaneous T-cell lymphoma

BackgroundAcquired ichthyosis is a known paraneoplastic sign of lymphoproliferative malignancies, with histopathologic findings that are nonspecific, revealing no insinuation of the underlying neoplasm. Ichthyosiform eruption as a specific manifestation of mycosis fungoides (MF), ie, ichthyosiform MF, is, however, regarded as rare and to date has been reported in only a few cases. ObjectiveWe sought to study the clinical, histopathologic, immunohistochemical, and genotypic features of patients with ichthyosiform MF. MethodsThe files of patients with MF seen during the past 8 years in our department were reviewed to search for cases of ichthyosis-like MF. ResultsSeven patients, comprising 3.5% of the patients seen with MF, had an ichthyosiform eruption with histopathologic features characteristic of early MF. In 2 patients it was the sole manifestation of the disease and in 5 patients it appeared either in conjunction with conventional patches and/or plaques or with follicular lesions. Immunohistochemically, all showed a predominance of CD3+ CD4+, except for 1 patient in whom the epidermotropic T cells were predominantly CD8+. In 3 of the 7 patients clonality could be demonstrated by polymerase chain reaction. None had extracutaneous involvement. All had an indolent course of the disease and responded well to skin-targeted therapies. ConclusionsIchthyosiform MF is yet another atypical clinical variant of cutaneous T-cell lymphoma that is not as rare as reflected in the literature. It may be the sole manifestation of the disease but also may appear in conjunction with conventional or follicular MF lesions.

Hypopigmented mycosis fungoides: frequent expression of a CD8+ T-cell phenotype.

Hypopigmented mycosis fungoides (MF) is a form of cutaneous T-cell lymphoma in which hypopigmentation occurs in the absence of classic lesions of MF. Hypopigmented MF predominantly affects people with dark complexions. The natural history of this variant of cutaneous T-cell lymphoma is similar to that of conventional MF, although the disease onset is usually in childhood or adolescence. In a retrospective study we evaluated the clinical, histopathologic, immunohistochemical, and molecular characteristics of hypopigmented MF in 15 patients. Similar to other reports, the disease onset occurred in childhood and adolescence in most of the cases. The survival rate was comparable with that of classic MF. We did not observe progression to systemic disease or lymph node involvement. Histopathologically hypopigmented lesions were indistinguishable from hyperpigmented or erythematous patches. On immunohistochemical analysis a predominantly CD8+ infiltrate was detected in the majority of cases (nine of 15 patients). To determine whether epidermotropic CD8+ T cells represent the malignant T-cell clone or whether these cells are innocent, tumor-infiltrating T lymphocytes, we performed microdissection of epidermotropic CD8+ T cells and analyzed T-cell receptor-gamma chain gene for rearrangements. The epidermotropic CD8+ T lymphocytes showed clonal T-cell receptor gene rearrangement and therefore represented the malignant T-cell clone. We conclude that hypopigmented MF tends to occur in young people and that it belongs to the group of CD8+ cutaneous T-cell lymphomas in the majority of cases.

Follicular cutaneous T-cell lymphoma: a clinicopathological study of nine cases.

Nine patients with follicular cutaneous T-cell lymphoma (CTCL), a recently described variant of lymphoma, are presented. On the basis of clinical manifestations and disease course, three groups of patients were distinguished: (i) two patients with follicular CTCL not associated with conventional lesions of mycosis fungoides (MF) and showing no evolution towards MF in follow-up periods of 3 and 6 years; (ii) one patient with follicular CTCL that evolved into conventional MF within 3 years; (iii) six patients showing conventional MF lesions either before or concurrently with the follicular lesions and thus representing follicular CTCL of the true MF type. The follicular lesions included hair-devoid patches or plaques with spiky hyperkeratotic papules (four patients), keratosis pilaris-like lesions (four), comedo-like lesions (four), follicular papules with alopecia (three) and milia-like lesions (three). Histopathological examination showed perifollicular and intrafollicular lymphocytes, without mucin deposition and with minimal or no involvement of the overlying epidermis. Significant syringotropism was also observed in three cases. Immunohistochemical analysis showed the predominance of CD4 + T cells, deletion of CD7 in some cases, Ki-67 + lymphocytes confined mainly to the follicular epithelium, and expression of keratinocyte intercellular adhesion molecule-1 exclusively in the hair follicle. T-cell receptor gamma gene rearrangement was positive in the one case studied from each group. Different treatment modalities were employed, the most commonly used as monotherapy being phototherapy: psoralen ultraviolet A in four patients, two of whom showed a complete clinical and histopathological remission, and ultraviolet B in one patient, who showed a complete remission (both clinical and histopathological). This study indicates that follicular CTCL is more common than reflected in the literature, has heterogeneous clinical manifestations, and is either an expression of or closely related to MF. The influence of the follicular involvement on the therapeutic response remains to be clarified. However, our therapeutic experience clearly suggests that some patients with follicular CTCL can benefit from phototherapy.