Vitamin D in Cutaneous T-Cell Lymphoma.

Cutaneous T-cell lymphoma (CTCL) is characterized by the proliferation of malignant T cells in inflamed skin lesions. Mycosis fungoides (MF)-the most common variant of CTCL-often presents with skin lesions around the abdomen and buttocks ("bathing suit" distribution), i.e., in skin areas devoid of sun-induced vitamin D. For decades, sunlight and vitamin D have been connected to CTCL. Thus, vitamin D induces apoptosis and inhibits the expression of cytokines in malignant T cells. Furthermore, CTCL patients often display vitamin D deficiency, whereas phototherapy induces vitamin D and has beneficial effects in CTCL, suggesting that light and vitamin D have beneficial/protective effects in CTCL. Inversely, vitamin D promotes T helper 2 (Th2) cell specific cytokine production, regulatory T cells, tolerogenic dendritic cells, as well as the expression of immune checkpoint molecules, all of which may have disease-promoting effects by stimulating malignant T-cell proliferation and inhibiting anticancer immunity. Studies on vitamin D treatment in CTCL patients showed conflicting results. Some studies found positive effects, others negative effects, while the largest study showed no apparent clinical effect. Taken together, vitamin D may have both pro- and anticancer effects in CTCL. The balance between the opposing effects of vitamin D in CTCL is likely influenced by treatment and may change during the disease course. Therefore, it remains to be discovered whether and how the effect of vitamin D can be tilted toward an anticancer response in CTCL.

Estimation of serum and tissue level of interleukin-15 (IL-15) and IL-15 receptor alpha (IL-15Rα) in mycosis fungoides before and after phototherapy: An interventional cohort study.

BACKGROUND: Mycosis fungoides (MF) is a chronic, highly recurrent cutaneous T-cell lymphoma, whose pathogenesis has not yet been fully elucidated. Interleukin-15 was previously highlighted as a viability factor for cutaneous T-cell lymphoma with previous studies shedding light on its role in pathogenesis of MF and its plausibility as a potential therapeutic target. OBJECTIVE: This study was conducted to evaluate serum and tissue expression of IL-15 and IL-15Rα in early cases of MF (IA, IB, IIA) at baseline and following phototherapy. MATERIALS AND METHODS: Fourteen early MF cases were recruited. Samples were withdrawn prior to starting phototherapy treatment and following near complete clearance of the biopsied lesion or after a maximum of 36 sessions of phototherapy. Samples were assessed for change in expression of IL-15 and IL-15 Rα levels following treatment, whose levels were compared to healthy controls. RESULTS: Serum and tissue levels of IL-15 and IL-15Rα in early MF cases were significantly higher at baseline than their levels following phototherapy treatment and higher than healthy controls. However, they dropped significantly following treatment with no statistical difference between treated cases and controls, apart from serum IL-15Rα that remained significantly elevated than controls. CONCLUSION: Interleukin-15 and its receptor alpha appear to contribute to the pathogenesis of MF, being significantly elevated than healthy controls, which were normalized following phototherapy treatment, apart from serum IL-15Rα, which remained elevated. Controlling IL-15/IL-15Rα expression is a newly proposed mechanism of action of phototherapy in MF.

Early intervention of extracorporeal photopheresis for advancing/progressing cutaneous T-cell lymphoma.

Patients with cutaneous T-cell lymphoma with progressive disease typically undergo a series of skin-directed and systemic therapy regimens during cycles of response and relapse. Extracorporeal photopheresis (ECP) is an effective and safe systemic treatment option, often reserved for later stages of disease and typically employed after failure of several other therapies. ECP has benefits in response rate, time to next treatment, and tolerability that may support its use earlier in the treatment cycle for advancing/progressing disease.

Paediatric Mycosis Fungoides: Clinical Variants, Treatment Modalities and Response to Therapy.

Mycosis fungoides is a rare cutaneous lymphoma in the paediatric population. The aim of this study was to examine the epidemiological, clinical, and histological characteristics, as well as the treatment modalities and response to therapy of paediatric patients with mycosis fungoides. This retrospective cohort study reviewed the records of 37 paediatric patients treated at Rambam Medical Center, Israel, between 2013 and 2021. Extracted data included epidemiology, clinical presentation, histological reports, infiltrate clonality status, treatment modalities and response to therapy. The mean follow-up period was 60 months. All patients were diagnosed with stage IA or IB disease. Folliculotropic mycosis fungoides was the most prevalent variant (49%). Most patients were treated with phototherapy (90%), with a response rate of 85%, and a complete response rate of 55% after the first course. There were no significant differences in response to phototherapy between the folliculotropic or other variants (p = 0.072). Similarly, delayed diagnosis, atopic diathesis, clonality, phototherapy type or number of treatments, were not associated with response to therapy, while protracted phototherapy was associated with prolonged remission. In conclusion, mycosis fungoides in the paediatric population is an indolent disease with a favourable prognosis and potentially prolonged response to phototherapy.

Gut microbiota analyses of cutaneous T-cell lymphoma patients undergoing narrowband ultraviolet B therapy reveal alterations associated with disease treatment.

Recent studies have shown a close relationship between cutaneous T-cell lymphoma (CTCL) and its microbiome. CTCL disease progression is associated with gut dysbiosis and alterations in bacterial taxa parallel those observed in immunologically similar atopic dermatitis. Moreover, the microbial profile of lesional skin may predict response to narrowband ultraviolet B (nbUVB), a common skin-directed therapy. However, the relationship between the gut microbiome, an immunologically vital niche, and nbUVB remains unexplored in CTCL. Herein, we performed 16S rRNA sequencing and PICRUSt2 predictive metagenomics on DNA extracted from stool swabs of 13 CTCL patients treated with nbUVB, 8 non-treated patients, and 13 healthy controls. Disease response was assessed with modified Severity Weighted Assessment Tool (mSWAT); of nbUVB-treated patients, 6 improved (decreased mSWAT), 2 remained stable, and 5 worsened (increased mSWAT). Protective commensal bacteria including Lactobacillaceae and Erysipelatoclostridiaceae were significantly less abundant in CTCL patients compared to controls. With treatment, the CTCL gut microbiome exhibited decreased phylogenetic diversity and lower relative abundance of pro-inflammatory Sutterellaceae. Sutterellaceae was also significantly more abundant in patients who worsened, and Eggerthellaceae and Erysipelotrichaceae trended higher in patients who improved. Finally, PICRUSt2 functional predictions based on shifts in abundance of bacterial sequences repeatedly identified alterations in inositol degradation, which plays a key role in host immunomodulation, including inositol phospholipid signaling relevant to T-cell survival and proliferation. Our results bolster the paradigm of gut dysbiosis in CTCL and its functional implications in disease pathogenesis, and further delineate bacterial taxa associated with nbUVB response and with nbUVB treatment itself.

Inhibition of Integrin αVß3 Signaling Improves the Antineoplastic Effect of Bexarotene in Cutaneous T-Cell Lymphoma.

Bexarotene is a specific retinoid X receptor agonist that has been used for the treatment of cutaneous T-cell lymphoma (CTCL). Because bexarotene causes hypothyroidism, it requires the administration of levothyroxine. However, levothyroxine, in addition to its ubiquitous nuclear receptors, can activate the αVß3 integrin that is overexpressed in CTCL, potentially interfering the antineoplastic effect of bexarotene. We thus investigated the biological effect of levothyroxine in relation to bexarotene treatment. Although in isolated CTCL cells levothyroxine decreased, in an αVß3-dependent manner, the antineoplastic effect of bexarotene, levothyroxine supplementation in preclinical models was necessary to avoid suppression of lymphoma immunity. Accordingly, selective genetic and pharmacologic inhibition of integrin αVß3 improved the antineoplastic effect of bexarotene plus levothyroxine replacement while maintaining lymphoma immunity. Our results provide a mechanistic rationale for clinical testing of integrin αVß3 inhibitors as part of CTCL regimens based on bexarotene administration. TEASER: Inhibiting αVß3 integrin improves the antineoplastic effect of bexarotene while maintaining lymphoma immunity.

Prognosis in early stage cutaneous T-cell lymphoma treated with psoralen plus ultraviolet A irradiation and low-dose interferon-α: Long-term efficacy and survival according to conventional and emerging clinical endpoints.

Patients with early stage cutaneous T cell lymphoma (CTCL) usually have a benign and chronic disease course, characterized by temporally response to conventional skin directed therapies and intrinsic possibility to evolve. Using the combination of psoralen plus ultraviolet A irradiation (PUVA) and low-dose interferon-α (INF), the principal treatment goal is to keep confined the disease to the skin, preventing disease progression. Among 87 patients with early stage IA to IIA MF treated with low-dose IFN-α2b and PUVA in our center, complete remission (CR) were reported in 70 patients (80.5%) and the overall response rate (ORR) was 97.8% (n = 85), with a median time to best response to therapy of 5 months (range, 1-30). Among the responders, only the 8% of patients had a relapse with major event. The median follow-up was 207 months (range, 6-295). Survival data showed a median overall survival (OS) not reached (95% CI; 235-NR months), a disease free survival (DFS) of 210 months (95% CI; 200-226 months) and a median time to next treatment (TTNT) of 38.5 months (95% CI, 33-46 months). The long follow up of this study verifies our preliminary results already published in 2006 and confirms the efficacy of INF-PUVA combination therapy in a real world setting, according conventional (OS and DFS) and emerging (TTNT) clinical endpoint of treatment efficacy.

Mycosis fungoides in pediatric population: comprehensive review on epidemiology, clinical presentation, and management.

Mycosis fungoides (MF) is the most common type of cutaneous T-cell lymphoma. However, it is rare in pediatric population. Most of the cases of pediatric MF present with hypopigmented patches and/or various other forms, which may often mimic common childhood dermatoses, thereby causing a delay in the diagnosis. There are no established treatment guidelines for pediatric MF. As the progression of childhood MF is extremely rare and it has an indolent course, it is usually diagnosed at an early stage (IA, IB, IIA), and hence phototherapy with a response rate of >80% is a well-established effective treatment in children. However, as recurrences are frequently seen on stopping the therapies, a maintenance regimen and long-term follow-up is equally important. This article reviews the epidemiological factors, clinical presentations, diagnosis, and various treatment modalities used in pediatric MF. We analyzed and compared the data of almost 616 childhood MF cases from various studies undertaken from 1988 to 2021.

Alitretinoin in the treatment of cutaneous T-cell lymphoma.

INTRODUCTION: In this survey, we analyzed data from patients suffering from the most common cutaneous T-cell lymphomas (CTCLs) subtypes mycosis fungoides (MF) and Sézary syndrome (SS), treated with the retinoid alitretinoin during a 7-year period at our outpatient department between 2015 and 2020. MATERIALS AND METHODS: We analyzed patient medical records including TNMB stage, side effects under therapy with alitretinoin, time to next treatment (TTNT), and previous photo documentation. RESULTS: A total of 35 patients with MF (n = 28) and SS (n = 7) were included in the study, of whom 69% were male and 31% were female. The mean age of onset was 56 ± 15 years in MF and 65.4 ± 10.8 years in SS with 51.4% having early stage (IA-IIA) and 48.6% having advanced stage (IIB-IVA) CTCL. Of these patients 37.2% responded to alitretinoin, 28.6% had a stable course, and 34.3% experienced progression. Alitretinoin was administered as a monotherapy (25.7%) or combined with five concomitant therapies (74.2%), most frequently with ECP (31.4%) and PUVA (11.4%). 63% did not report any side effects, most often hypertriglyceridemia (20%) was described. CONCLUSION: Considering that nearly two thirds of the CTCL patients treated with alitretinoin showed a response or stable disease, together with a low number of side effects and low cost compared to bexarotene, alitretinoin may be a potential alternative in the treatment of less advanced CTCLs. This survey represents the largest number of recorded therapies with the retinoid alitretinoin in CTCLs in a European patient collective.

Novel therapeutic approaches for cutaneous T cell lymphomas.

Introduction: Cutaneous T-cell lymphoma (CTCL) is a rare non-Hodgkin's lymphoma, characterized by malignant T cells infiltrating the skin. CTCL exhibits vast heterogeneity which complicates diagnosis and therapeutic strategies. Current CTCL treatment includes skin-directed therapies (such as topical corticosteroid, topical mechlorethamine, topical bexarotene, ultraviolet phototherapy and localized radiotherapy), total skin electron beam therapy and systemic therapies. Elucidation of molecular and signaling pathways underlying CTCL pathogenesis leads to identification of innovative and personalized treatment schemes.Areas covered: The authors reviewed the molecular and immunological aspects of CTCL with special focus on Mycosis Fungoides (MF), Sézary Syndrome (SS) and associated systemic treatment. A literature search was conducted in PubMed and Web of Science for peer-reviewed articles published until November 2020. Novel treatment approaches including retinoids, targeted therapies, immune checkpoint and JAK/STAT inhibitors, histones deacetylase (HDAC) and mTOR inhibitors as well as proteasome inhibitors, are discussed as potential therapeutic tools for the treatment of CTCL.Expert opinion: Novel therapeutic agents exhibit potential beneficial effects in CTCL patients of high need for therapy such as refractory early stage cutaneous and advanced stage disease. Therapeutic schemes employing a combination of novel agents with current treatment options may prove valuable for the future management of CTCL patients.

Dermatologists are more likely than oncologists to prescribe skin-directed therapies for early-stage cutaneous T-cell lymphoma: a retrospective review.

Early-stage cutaneous T-cell lymphoma (CTCL) is managed effectively with skin-directed therapies such as topical medications, phototherapy, and local ionizing radiation. Patients with CTCL often seek care from both dermatologists and oncologists. Our study aimed to compare the frequency that skin-directed treatments were prescribed to patients managed by each of these specialties. Overall, we found there was a statistically detectable relationship between the presence or absence of oncologist involvement and the likelihood that a patient would be prescribed skin-directed therapies (P=0.0003). Of the oncologists included in the study, 66% opted for management revolving around systemic rather than skin-directed therapies. However, when a dermatologist and oncologist worked together in a patient's care, the number of patients receiving skin-directed therapies increased to 100%. Our study suggests that patients with early stage CTCL may benefit from having a dermatologist involved in their care.

Efficacy and safety of bexarotene combined with photo(chemo)therapy for cutaneous T-cell lymphoma.

Cutaneous T-cell lymphoma (CTCL) is a chronic condition with low malignancy. International treatment guidelines for CTCL are widely followed in Europe and the USA. Combination therapy with therapeutic agents for CTCL and phototherapy is effective on the basis of European data. The efficacy and safety of combination therapy for Japanese CTCL patients are not established. We investigated the efficacy and safety of combination therapy with photo(chemo)therapy and bexarotene in Japanese CTCL patients. Twenty-five patients received daily oral bexarotene (300 mg/m2 body surface), followed by bath-psoralen plus ultraviolet (UV)-A (PUVA) or narrowband UV-B. Treatment results were evaluated using the modified Severity-Weighted Assessment Tool (mSWAT) and the Physician Global Assessment of Clinical Condition (PGA) up to week 24. Safety was also assessed. Twenty-four weeks after initiating treatment, the total response rate was 80.0% (mSWAT) and 84.0% (PGA). Response rates did not differ when stratified by disease stage. Number of days (mean ± standard deviation) for time to response, duration of response and time to progression determined by the mSWAT were 20.7 ± 9.62, 117.0 ± 43.0 and 163.6 ± 28.8, respectively. T-helper 2 chemokine levels in patients at stage IIA or more decreased significantly at weeks 12 and 24. All patients experienced adverse events and adverse drug reactions. Serious adverse drug reactions included sepsis, anemia and congestive cardiac insufficiency (n = 1 each). Other adverse drug reactions were of mild to moderate severity. Combination therapy with bexarotene and PUVA was safe and effective in Japanese CTCL patients.

Real-world use of extracorporeal photopheresis for patients with cutaneous T-cell lymphoma in the United States: 2010-2015.

Introduction: The National Comprehensive Cancer Network and the European Organization for Research and Treatment of Cancer recommend extracorporeal photopheresis (ECP) as systemic therapy for cutaneous T-cell lymphoma (CTCL).Objective: To investigate real-world use of ECP in CTCL patients in the US.Methods: Data from the Truven MarketScan® database (2010-2015) were used to create a cohort of CTCL patients receiving systemic treatment. Multivariable regressions were performed to compare health care resource utilization between ECP and propensity score-matched non-ECP patients.Results: Of the 1106 eligible patients, 117 (10.6%) received ECP, with an average treatment duration of 13.6 months. Psoriasis, organ transplant, graft versus host disease, and scleroderma were the most common comorbidities. ECP was used as monotherapy in 76 patients (65.0%) and combination in 41 patients (35.0%), mostly with interferon and/or a retinoid. Higher Charlson Comorbidity Index (2.6 vs 2.2, p < .05), rates of organ transplant (49.6% vs 7.8%, p < .001), and graft vs host disease (41.9% vs 3.4%, p < .001) were observed in ECP versus non-ECP patients. Post-matching analyses showed that ECP patients had shorter all-cause inpatient stay (6.67 vs 11.80 days, p = .001).Conclusions: Approximately 1 out of 10 CTCL patients receiving systemic treatment were on ECP treatment in the US. Post-matching analysis showed ECP was associated with a shorter hospital stay.

Cutaneous T Cell Lymphoma: A Difficult Diagnosis Demystified.

Cutaneous T cell lymphoma (CTCL) represents a heterogeneous group of extranodal non-Hodgkin lymphomas in which monoclonal T lymphocytes infiltrate the skin. The mechanism of CTCL development is not fully understood, but likely involves dysregulation of various genes and signaling pathways. A variety of treatment modalities are available, and although they can induce remission in most patients, the disease may recur after treatment cessation. Owing to relatively low incidence and significant chronicity of disease, and the high morbidity of some therapeutic regimens, further clinical trials are warranted to better define the ideal treatment option for each subtype of CTCL.

Therapeutic Efficacy of Etretinate on Cutaneous-type Adult T-cell Leukemia-Lymphoma.

Cutaneous-type adult T-cell leukemia-lymphoma is treated with antiviral or skin-directed therapy. Medications that are used to treat skin lesions of cutaneous T-cell lymphomas are also used for the cutaneous-type adult T-cell leukemia-lymphoma. Etretinate, a synthetic retinoid, has been used for treating cutaneous T-cell lymphomas; however, its clinical effectiveness for the treatment of cutaneous-type adult T-cell leukemia-lymphoma has not been fully studied. We conducted a retrospective assessment of the efficacy and safety of etretinate in 9 patients with cutaneous-type adult T-cell leukemia-lymphoma. Complete and partial responses to etretinate were observed in 1 and 7 patients, respectively. Among the responders, remission was maintained for more than 6 years in 2 patients. These results suggest that etretinate is a promising treatment option for cutaneous-type adult T-cell leukemia-lymphoma.

Management of cutaneous T-cell lymphomas: Established and emergent therapies.

Cutaneous T-cell lymphoma is an uncommon group of non-Hodgkin's lymphoma primarily affecting the skin. It is comprised of a variety of entities with different clinical behaviours and prognosis. Mycosis fungoides is the commonest subtype, and Sézary syndrome is a much rarer form of cutaneous T-cell lymphoma. At this stage, control rather than cure is the goal of therapy, with particular emphasis placed on preserving quality of life. Our review of the efficacy, safety profile and accessibility of treatment modalities for mycosis fungoides/Sézary syndrome is a tailored guide for the clinician treating these rare conditions.

The retinoid X receptor agonist, 9-cis UAB30, inhibits cutaneous T-cell lymphoma proliferation through the SKP2-p27kip1 axis.

BACKGROUND: Bexarotene (Targretin®) is currently the only FDA approved retinoid X receptor (RXR) -selective agonist for the treatment of cutaneous T-cell lymphomas (CTCLs). The main side effects of bexarotene are hypothyroidism and elevation of serum triglycerides (TGs). The novel RXR ligand, 9-cis UAB30 (UAB30) does not elevate serum TGs or induce hypothyroidism in normal subjects. OBJECTIVES: To assess preclinical efficacy and mechanism of action of UAB30 in the treatment of CTCLs and compare its action with bexarotene. METHODS: With patient-derived CTCL cell lines, we evaluated UAB30 function in regulating growth, apoptosis, cell cycle check points, and cell cycle-related markers. RESULTS: Compared to bexarotene, UAB30 had lower half maximal inhibitory concentration (IC50) values and was more effective in inhibiting the G1 cell cycle checkpoint. Both rexinoids increased the stability of the cell cycle inhibitor, p27kip1 protein, in part, through targeting components involved in the ubiquitination-proteasome system: 1) decreasing SKP2, a F-box protein that binds and targets p27kip1 for degradation by 26S proteasome and 2) suppressing 20S proteasome activity (cell line-dependent) through downregulation of PSMA7, a component of the 20S proteolytic complex in 26S proteasome. CONCLUSIONS: UAB30 and bexarotene induce both early cell apoptosis and suppress cell proliferation. Inhibition of the G1 to S cell cycle transition by rexinoids is mediated, in part, through downregulation of SKP2 and/or 20S proteasome activity, leading to increased p27kip1 protein stability. Because UAB30 has minimal effect in elevating serum TGs and inducing hypothyroidism, it is potentially a better alternative to bexarotene for the treatment of CTCLs.

[Treatment of rare cutaneous T­cell lymphoma and blastic plasmacytoid dendritic cell neoplasm]. / Therapie seltener kutaner T­Zell-Lymphome und der blastären plasmazytoiden dendritischen Zellneoplasie.

Among the group of primary cutaneous lymphomas several subtypes have very low incidence rates. Based on the revision of the WHO classification for lymphoid neoplasms (2016), an overview of rare cutaneous T­cell lymphoma (CTCL) subtypes is given and therapeutic approaches are detailed. The prognosis of the different subtypes is highly variable underlining the importance of adequate stage and subtype adapted treatment. In cases of indolent subtypes topical treatment, e. g. topical corticosteroids or UV phototherapy are often sufficient. For aggressive variants, early discussion of more aggressive systemic treatment options is warranted.

Micosis fungoide. Experiencia en un hospital pediátrico / Mycosis Fungoides: Experience in a Pediatric Hospital

La micosis fungoide (MF) es el linfoma cutáneo primario de células T más frecuente. Su aparición en la infancia es excepcional. Objetivos: Describir las características epidemiológicas, clínicas, histopatológicas e inmunofenotípicas de los pacientes con MF. Describir los tratamientos utilizados y la evolución. Material y método: Se incluyeron todos los pacientes admitidos en el Hospital de Pediatría Dr. J. P. Garrahan (Argentina) en el período comprendido entre agosto de 1988 y julio de 2014 con diagnóstico clínico e histopatológico de MF. Resultados: Se diagnosticaron 14 pacientes con MF. La distribución por sexo fue M/F: 1:1,33. La edad media al diagnóstico fue de 11,23 años (rango: 8 a 15 años). El tiempo promedio de evolución hasta el momento del diagnóstico fue de 3 años y 6 meses (rango: 4 meses a 7 años). Todos los pacientes presentaron la forma clínica hipopigmentada y en el 42% se asoció la forma clásica. El 50% (n = 7) exhibió un inmunofenotipo CD8 positivo de forma exclusiva. El 78% presentó estadio IB. La fototerapia fue el tratamiento de elección. Cuatro pacientes tuvieron por lo menos una recaída y 3 demostraron progresión de su enfermedad a nivel cutáneo. La evolución fue favorable en todos los casos. Conclusiones: La MF es una entidad infrecuente en la infancia, siendo la forma hipopigmentada la más frecuente. Su diagnóstico es tardío debido a la similitud con otras enfermedades hipopigmentadas frecuentes en la niñez. A pesar de tener un buen pronóstico, presenta alta tasa de recidivas y requiere un seguimiento a largo plazo (AU)

Mycosis fungoides (MF), the most common primary cutaneous T-cell lymphoma, is unusual in children. Objectives: We aimed to describe the epidemiologic, clinical, histopathologic, and immunophenotypic characteristics of MF as well as treatments and course of disease in a pediatric case series. Material and method: Data for all patients admitted to our pediatric hospital (Hospital Dr. J. P. Garrahan) in Argentina with a clinical and histopathologic diagnosis of MF between August 1988 and July 2014 were included. Results: A total of 14 patients were diagnosed with MF. The ratio of boys to girls was 1:1.33. The mean age at diagnosis was 11.23 years (range, 8-15 years). The mean time between onset and diagnosis was 3.5 years (range, 4 months-7 years). All patients had hypopigmented MF and 42% also presented the features of classic MF. Seven (50%) had the CD8+ immunophenotype exclusively. Seventy-eight percent were in stage IB at presentation. Phototherapy was the treatment of choice. Four patients relapsed at least once and skin lesions progressed in 3 patients. All patients improved. Conclusions: MF is unusual in children. The hypopigmented form is the most common. Diagnosis is delayed because the condition is similar to other hypopigmented diseases seen more often in childhood. Although prognosis is good, the rate of recurrence is high, so long-term follow-up is necessary (AU)