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Clinicopathological features, MCPyV status and outcomes of Merkel cell carcinoma in solid-organ transplant recipients: a retrospective, multicentre cohort study. J Eur Acad Dermatol Venereol 2022; 36:1991-2001. [PMID: 35607918 PMCID: PMC9796956 DOI: 10.1111/jdv.18256] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Accepted: 04/13/2022] [Indexed: 01/07/2023]
Abstract
BACKGROUND The proportion of Merkel cell carcinomas (MCCs) in solid-organ transplant recipients (SOTR) harbouring Merkel cell polyomavirus (MCPyV) is unknown, as are factors affecting their outcomes. OBJECTIVE To describe clinicopathological features of MCC in SOTR, investigate the tumoral MCPyV-status and identify factors associated with tumour outcomes. METHODS Retrospective, international, cohort-study. MCPyV-status was investigated by immunohistochemistry and polymerase chain reaction. RESULTS A total of 30 SOTR and 44 consecutive immunocompetent patients with MCC were enrolled. SOTR were younger at diagnosis (69 vs. 78 years, P < 0.001). Thirty-three percent of SOTR MCCs were MCPyV-positive vs. 91% of immunocompetent MCCs (P = 0.001). Solid-organ transplantation was associated with an increased cumulative incidence of progression (SHR: 3.35 [1.57-7.14], P = 0.002), MCC-specific mortality (SHR: 2.55 [1.07-6.06], P = 0.034) and overall mortality (HR: 3.26 [1.54-6.9], P = 0.002). MCPyV-positivity and switching to an mTOR inhibitor (mTORi) after MCC diagnosis were associated with an increased incidence of progression (SHR: 4.3 [1.5-13], P = 0.008 and SHR: 3.6 [1.1-12], P = 0.032 respectively) in SOTR. LIMITATIONS Retrospective design and heterogeneity of SOTR cohort. CONCLUSIONS MCPyV appears to play a less prominent role in the aetiopathogenesis of MCC in SOTR. SOTR have a worse prognosis than their immunocompetent counterparts and switching to an mTORi after the diagnosis of MCC does not improve progression.
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Line‐field confocal optical coherence tomography of basosquamous carcinoma: A case series with histopathological correlation. J Eur Acad Dermatol Venereol 2022; 36:1214-1218. [DOI: 10.1111/jdv.18038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Accepted: 02/15/2022] [Indexed: 11/29/2022]
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Line-field confocal optical coherence tomography for actinic keratosis and squamous cell carcinoma: a descriptive study. Clin Exp Dermatol 2021; 46:1530-1541. [PMID: 34115900 PMCID: PMC9293459 DOI: 10.1111/ced.14801] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/10/2021] [Indexed: 11/28/2022]
Abstract
BACKGROUND Early and accurate diagnosis of cutaneous squamous cell carcinomas (SCCs) and actinic keratoses (AK) is fundamental to reduce their associated morbidity and to select the correct treatment. Line-field confocal optical coherence tomography (LC-OCT) is a new imaging device that can characterize healthy skin and basal cell carcinoma, but no large studies on keratinocyte cell tumours have yet been published. AIM To identify and describe LC-OCT criteria associated with SCC and AK, and to compare LC-OCT findings in these tumours. METHODS A retrospective observational multicentre study was conducted. Lesions were imaged with the LC-OCT device before surgery and examined histologically. LC-OCT criteria for AK/SCC were identified and their presence was evaluated in all study lesions. Univariate and multivariate analyses were performed to compare AK and SCCs, and to investigate differences between in situ and invasive tumours. RESULTS In total, 158 patients with 50 AK and 108 SCCs (62 in situ and 46 invasive) were included. Cytological and architectural alterations were found in most lesions, and differences were found between AK and SCCs. Although the visualization of the dermoepidermal junction (DEJ) was often hampered by hyperkeratosis and acanthosis, an outlined DEJ without broad strands was observed in almost all AK and almost all in situ SCCs, but in only three invasive SCCs (P < 0.001) when the DEJ was detectable. CONCLUSION Our results suggest that LC-OCT can help clinicians in the identification of AK and SCC and their differentiation, providing a real-time and noninvasive examination. Further studies are needed to confirm our data.
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一项关于在化脓性汗腺炎研究中使用词语“加剧”的回顾. Br J Dermatol 2020. [DOI: 10.1111/bjd.18677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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5
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Sunbed use legislation in Europe: assessment of current status. J Eur Acad Dermatol Venereol 2019; 33 Suppl 2:89-96. [DOI: 10.1111/jdv.15317] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 09/20/2018] [Indexed: 12/17/2022]
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6
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Low and high body mass index in hidradenitis suppurativa patients-different subtypes? J Eur Acad Dermatol Venereol 2017; 32:307-312. [DOI: 10.1111/jdv.14599] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Accepted: 09/07/2017] [Indexed: 01/03/2023]
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7
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The impact of dermoscopy on melanoma detection in the practice of dermatologists in Europe: results of a pan-European survey. J Eur Acad Dermatol Venereol 2017; 31:1148-1156. [DOI: 10.1111/jdv.14129] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Accepted: 01/02/2017] [Indexed: 01/27/2023]
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9
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The Euromelanoma campaign. ACTAS DERMO-SIFILIOGRAFICAS 2016. [DOI: 10.1016/j.adengl.2016.05.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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Establishment of a European Registry for hidradenitis suppurativa/acne inversa by using an open source software. J Eur Acad Dermatol Venereol 2015; 30:1424-6. [DOI: 10.1111/jdv.13267] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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12
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[Orf nodules and immunosuppression: a case report and review of therapeutics]. REVUE MEDICALE DE BRUXELLES 2015; 36:439-443. [PMID: 26749636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
In immunocompromised patient, parapoxvirus infection can be extensively necrotic and recurrent evolution. We describe a case of Orf nodule in a liver transplanted woman. We will consider the therapeutic options in case of infections by parapox in immunosuppressive patients, as described in the medical literature. In our specific case, local application of cidofovir (concentration of 1 %) together with local antiseptic solution, povidone iodine, led to complete remission of the lesion without any sign of toxicity. Finally, we will consider the therapeutic use of local cidofovir.
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[Melanoma secondary prevention]. REVUE MEDICALE DE BRUXELLES 2015; 36:255-259. [PMID: 26591309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Melanoma represents a major public health problem. Its incidence is constantly rising and the mortality rate can be frightfully important if the diagnosis is delayed. Melanoma also exerts a significant economical burden on the society. Therefore there is a need of concrete and pragmatic public health strategies in order to enhance melanoma prevention. Primary prevention of melanoma consists in avoiding excessive exposure to ultraviolet rays,'which represent the main risk factor for the disease occurrence. Secondary prevention is a synonym of melanoma early diagnosis and can be obtained by means of two methods : patients' self-examination and medical examination. Both these examinations must be routinely and thoroughly performed, must be based on the ABCDE rule and the ugly duckling sign, and ideally must be aided by the use of total-body photography. Current international guidelines suggest that all cutaneous screenings should be performed using dermoscopy, a non-invasive imaging technique that allows improving considerably the diagnostic performance. More sophisticated imaging techniques, such as confocal microscopy, are also available in specialised centres. The current scientific evidence supports the efficacy of melanoma primary and secondary prevention programs as a tool to decrease melanoma mortality. Many skin cancer prevention campaigns have been organised worldwide. The most famous and successful in Europe is Euromelanoma.
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Profile of the Belgian dermatologist: results of an online survey. J Eur Acad Dermatol Venereol 2014; 28:667-8. [DOI: 10.1111/jdv.12227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Revised: 06/30/2013] [Accepted: 07/03/2013] [Indexed: 11/28/2022]
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Impact, challenges and perspectives of Euromelanoma, a pan-European campaign of skin cancer prevention. J Eur Acad Dermatol Venereol 2013; 27:1317-9. [PMID: 23294192 DOI: 10.1111/jdv.12060] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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18
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[The use of lasers in dermatology]. REVUE MEDICALE DE BRUXELLES 2013; 34:12-19. [PMID: 23534310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Albert Einstein is undoubtedly the father of lasers. But it is not until 1964 that the first dermatological lasers were introduced. The Nd-YAG laser, the CO2 laser were developed by Kumar Patel. In a 40 year period lasers not only were diversified but have also become safer and miniaturized. This article hopes to strengthen general practionners' and specialist's knowledge of the different categories of available lasers. The most frequently used ones are ablative lasers (CO2-Erbium), vascular lasers (Nd-YAG, KTP, pulsed dye laser) and the pigment lasers (Q-Switched Nd-YAG, Alexandrite). A description of these lasers and their indications in dermatology will be discussed.
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Euromelanoma: a dermatology-led European campaign against nonmelanoma skin cancer and cutaneous melanoma. Past, present and future. Br J Dermatol 2012; 167 Suppl 2:99-104. [DOI: 10.1111/j.1365-2133.2012.11092.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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The Euromelanoma skin cancer prevention campaign in Europe: characteristics and results of 2009 and 2010. J Eur Acad Dermatol Venereol 2011; 25:1455-65. [PMID: 21951235 DOI: 10.1111/j.1468-3083.2011.04228.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND Euromelanoma is a skin cancer education and prevention campaign that started in 1999 in Belgium as 'Melanoma day'. Since 2000, it is active in a large and growing number of European countries under the name Euromelanoma. OBJECTIVE To evaluate results of Euromelanoma in 2009 and 2010 in 20 countries, describing characteristics of screenees, rates of clinically suspicious lesions for skin cancer and detection rates of melanomas. METHODS Euromelanoma questionnaires were used by 20 countries providing their data in a standardized database (Belgium, Croatia, Cyprus, Czech Republic, FYRO Macedonia, Germany, Greece, Hungary, Italy, Lithuania, Luxembourg, Malta, Moldavia, Portugal, Serbia, Slovenia, Spain, Sweden, Switzerland and Ukraine). RESULTS In total, 59,858 subjects were screened in 20 countries. Most screenees were female (64%), median ages were 43 (female) and 46 (male) and 33% had phototype I or II. The suspicion rates ranged from 1.1% to 19.4% for melanoma (average 2.8%), from 0.0% to 10.7% for basal cell carcinoma (average 3.1%) and from 0.0% to 1.8% for squamous cell carcinoma (average 0.4%). The overall positive predictive value of countries where (estimation of) positive predictive value could be determined was 13.0%, melanoma detection rates varied from 0.1% to 1.9%. Dermoscopy was used in 78% of examinations with clinically suspected melanoma; full body skin examination was performed in 72% of the screenees. CONCLUSION Although the population screened during Euromelanoma was relatively young, high rates of clinically suspected melanoma were found. The efficacy of Euromelanoma could be improved by targeting high-risk populations and by better use of dermoscopy and full body skin examination.
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[Managing moles in general practice]. REVUE MEDICALE DE BRUXELLES 2011; 32:205-209. [PMID: 22034746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The purpose of this article is to improve the general practitioner's knowledge about nevi and to teach how to evaluate the risk of a lesion during a medical visit. The most frequent kind of nevi will be defined, as well as their transformation risk. Different melanoma risk factors and the semiology that can alert the practitioner will be defined. A set of the most frequently asked questions about nevi will be answered.
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New approach in photoprotection: alpha-Melanotropin (αMSH) analogs. Melanoma Res 2010. [DOI: 10.1097/01.cmr.0000382754.40130.71] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Abstract
Acne and seborrhea (or facial oiliness) are related androgenic skin disorders which affect a high proportion of women after menarche. They can have a negative effect on psychological well-being and social life. Androgens play an important role in the pathogenesis of acne through the stimulation of sebum secretion, increasing sebaceous gland size and possibly through follicular hyperkeratinization. Conversely, estrogens decrease sebum production by suppressing gonadotropin release and androgen production and increasing sex hormone binding globulin production. One of the treatment options for these conditions is hormonal therapy, especially for women who require contraception. The effect of combined oral contraceptives in androgenic skin disorders depends on their estrogen:progestogen balance and on the antiestrogenic activity of the progestogen component. Improved understanding of what women value about oral contraceptives suggests that the choice of product should be tailored as much as possible to the individual. Several combined oral contraceptives containing new-generation progestogens (e.g. desogestrel, gestodene) or progestational antiandrogens (e.g. cyproterone acetate, chlormadinone acetate) have demonstrated efficacy in the treatment of women with acne, although comparisons between trials are difficult because of differing endpoints. Seborrhea has been less well studied, but the few studies that are available show an improvement in women with this condition using combined oral contraceptives.
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A Prime minister managed to attract elderly men in a Belgian Euromelanoma campaign. Eur J Cancer 2009; 45:1532-4. [DOI: 10.1016/j.ejca.2008.12.023] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2008] [Revised: 12/16/2008] [Accepted: 12/18/2008] [Indexed: 10/21/2022]
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[What is the management for foot ulcers in diabetic patients?]. REVUE MEDICALE DE BRUXELLES 2009; 30:29-35. [PMID: 19353940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The "diabetic foot" covers the spectrum of neurological, arterial and infectious foot problems that occur as a consequence of diabetes. The wounds, often due to minor injuries, may lead to amputations if not quickly treated. The treatment consists of efficiently alleviating mechanical pressure from the wound (i.e. prevention of repeated trauma by walking on the ulcer) on the one hand, and using adequate local care on the other. In addition, the patient's vascular status needs to be assessed and corrected. If present, infections must be quickly and aggressively treated. The infection may be either superficial or deep and the presence of bone contact at clinical examination is suggestive of osteitis. Optimal care is provided in diabetic foot centers by multidisciplinary teams. These teams include a diabetologist, dermatologist, vascular surgeon, infectiologist, radiologist, podologist, shoemaker and specialized nurses. The main aim is to reduce the number of amputations. The best treatment, however, aims at prevention of foot wounds. It requires knowledge of the physiopathological mechanisms of diabetic foot, the screening for feet at risk, and the education of the patient, family and health care providers.
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Melanoma in organ transplant recipients: clinicopathological features and outcome in 100 cases. Am J Transplant 2008; 8:1891-900. [PMID: 18786232 DOI: 10.1111/j.1600-6143.2008.02326.x] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Organ transplant recipients have a higher incidence of melanoma compared to the general population but the prognosis of this potentially fatal skin cancer in this group of patients has not yet been established. To address this, we undertook a multicenter retrospective analysis to assess outcome for 100 melanomas (91 posttransplant and 9 pretransplant) in 95 individuals. Data were collected in 14 specialist transplant dermatology clinics across Europe belonging to the Skin Care in Organ Transplant Patients, Europe (SCOPE) Network, and compared with age, sex, tumor thickness and ulceration status-matched controls from the American Joint Committee on Cancer (AJCC) melanoma database. Outcome for posttransplant melanoma was similar to that of the general population for T1 and T2 tumors (< or = 2 mm thickness); but was significantly worse for T3 and T4 tumors (> 2 mm thickness); all nine individuals with a pretransplant melanoma survived without disease recurrence following organ transplantation. These data have implications for both cutaneous surveillance in organ transplant recipients and management of transplant-associated melanoma.
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Nephrogenic systemic fibrosis--the need for a multidisciplinary approach. Nephrol Dial Transplant 2007. [DOI: 10.1093/ndt/gfm892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Epidemiology of nonmelanoma skin cancer (NMSC) in Europe: accurate and comparable data are needed for effective public health monitoring and interventions. Br J Dermatol 2007; 156 Suppl 3:1-7. [PMID: 17488399 DOI: 10.1111/j.1365-2133.2007.07861.x] [Citation(s) in RCA: 145] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Nonmelanoma skin cancer (NMSC) is the most common malignancy occurring in white populations. It is currently becoming an important challenge in terms of public health management as the increasing incidence rates will probably have a tremendous impact on healthcare costs. Possible factors driving this rise in NMSC numbers are increases in both acute and prolonged UV exposure together with increasing numbers of older people in the population. A better understanding of NMSC epidemiology in Europe is essential if an evidence-based European-wide public health policy is to be developed. It is obvious this can only be achieved by recording and analysing comparative epidemiological data. Finally, by improving the skin examination training for physicians, developing guidelines and exchanging best practices, a high level of healthcare could be provided for NMSC.
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[Androgenetic alopecia]. REVUE MEDICALE DE BRUXELLES 2004; 25:A277-81. [PMID: 15516056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Abstract
The physiopathology of androgenetic alopecia is linked to the action of the androgens of the bulbs pilairs of the scalp. The action of these androgens can be associated with the level of hormones in circulation and with the genetic predisposition which will influence the activity of these androgens at the periphery. The classifications of the evolution of alopecia will be done following Norwood for the male and following Ludwig for the female. Hormonal investigation will be effectuated on the female only in the case of research on or the identification of hyperandrogenia; this is essential in order to direct the therapy. The diagnose and the therapeutic follow-up are essentially clinical but can be assisted by a trichogram which will show-up the miniaturisation process of androgenetic alopecia and the telogen effluvium of the affected areas. The treatment of alopecia can be local or general. The local treatment will use a lotion of minoxidil 2 to 5% whether the patient is male of female. On males, an inhibitor of the 5 alpha reductase 2, finasteride, has shown its efficiency at a dose of 1 mg/day. On females oestroprogestatives will be used, if they are not counter-advised, associated with an anti-androgen: either cyproterone acetate or spironolactone. A therapeutic evaluation will be made after 6 months of treatment.
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[Clinical tools for assessing hair loss]. REVUE MEDICALE DE BRUXELLES 2004; 25:A269-72. [PMID: 15516054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Abstract
The complaint of hair loss is quite frequent but merits close attention because it can be very stressful to the patient. A simple examination will allow in most cases to define the origin of the hair loss and reassure the patient rapidly as to its likely evolution if it is reversible. The examination must take into account the medical, chirurgical, gynaecological and dietary antecedents and the cosmetic habits. These elements must be situated in time and complemented by a clinical examination to define the loss as diffuse or localised and in the latter case, expose scar damage. The clinical examination will be associated with a trichogram and in certain cases with a biopsy or a squam prelevement. Further, the blood can be analysed for different metabolically and hormonal elements. Finally, the treatments already administered must be known in order to identify the beneficial and secondary effects, which will allow the definition of a new treatment, if required.
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Abstract
BACKGROUND Although the incidence of melanoma is increasing and many informative campaigns have been organized. The general population is still little informed about this tumour. AIMS To organize a media campaign, with more relevant information and the opportunity for free skin inspections. METHODS A 'Task Force' organized a media campaign in April 1999 and convinced 65% of the Belgian dermatologists to give up 4 h of their time to do free skin examinations for skin cancer on Monday 26 April 1999; it was called 'Melanoma Monday'. RESULTS A total 2767 patients were screened. We found 25 melanomas and suspected 59 basal cell carcinomas. In the following 4 weeks another 141 melanomas were found. These 166 melanomas found in one month represent 15-20% of the total number of melanomas per year in Belgium. SUMMARY A media campaign with relevant information combined with screening opportunities can lead to the early detection of melanomas in a large number of patients and can continue to alert people at risk in the following weeks.
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Comparison of HPLC and stereologic image analysis for the quantitation of eu- and pheomelanins in nevus cells and stimulated melanoma cells. J Invest Dermatol 1998; 111:422-8. [PMID: 9740235 DOI: 10.1046/j.1523-1747.1998.00313.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The aim of the study was to compare two methods of quantitating eumelanins and pheomelanins, pigments synthesized by melanocytes. One is based on the high performance liquid chromatography quantitation of specific degradation products of each melanin type. The other requires image analysis, transmission electron microscopy, and stereology. In a previous study, we showed good correlations between both methods for total melanin but not for eumelanins or pheomelanins. We describe here the same comparison in more pigmented cells (nevus cells and stimulated HBL melanoma cells). Transmission electron microscopy micrographs were image analyzed to generate several primary parameters. Stereology was used for estimating melanosomal maturation, intracellular melanin content, and the number of melanized melanosomes per cell, for total melanin, eumelanins, or pheomelanins. Our results showed a good correlation between both methods for total melanin, eumelanins, and pheomelanins with an r equal to 0.99, 0.91, and 0.93, respectively, when all the points were used in the linear regression analyses. In the melanoma cell group (HBL cells cultured in media of different compositions), the chemical and morphometric estimations were not parallel in the case of eumelanins and pheomelanins. In addition, the stereologic and high performance liquid chromatography pheomelanins to eumelanins ratios were still not correlated. These results demonstrate the relevancy of the stereologic method, but the low level of melanization, the possible lack of specificity of melanogenesis in melanoma cells, and a problem of sensitivity of the stereologic method in this context seem to be obstacles in obtaining better results. The utilization of normal human melanocytes could give some answers to our hypotheses.
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Quantification of eumelanin and pheomelanin: stereologic image analysis method. ANALYTICAL AND QUANTITATIVE CYTOLOGY AND HISTOLOGY 1998; 20:275-87. [PMID: 9739410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
OBJECTIVE To develop an ultrastructural stereologic image analysis method allowing quantification of intracellular melanization. STUDY DESIGN First, in the field of image analysis, a newly elaborated segmentation method, SEM2, was compared with a previously described method based on gray level histograms. Only SEM2 allows the segmentation of melanin in micrographs of poorly melanized melanocytes. Second, in the field of stereology, estimation of cell volume remains problematic in the case of mixed cell populations. This problem is approached by the comparison of stereologic alternatives and cytochemistry (L-3, 4-dihydroxyphenylalanine reaction) in epidermal melanocytes and melanoma cells from several in vitro experiments. The cytochemical approach was found to be the best choice. RESULTS Concerning the quantification of eumelanin and pheomelanin, the alkali elution method, permitting the specific dissolution of pheomelanin on ultrathin sections, was validated in normal human follicular melanocytes. CONCLUSION These results allow us to envisage the stereologic quantification of eumelanin and pheomelanin at the ultrastructural level. At present our method is undergoing evaluation by comparison with the present method of reference based on high-performance liquid chromatography.
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Abstract
Most of our knowledge of the mammalian tyrosinase related protein (TRP) activities is derived from studies using murine melanoma models, such as B16 or Cloudman S-91 melanocytes. Owing to the high degree of homology between the murine and human enzymes, it has been assumed that their kinetic behaviour could be similar. However, the protein sequences at the metal binding sites of the murine and human enzymes show some differences of possible functional relevance. These differences are more significant in the metal-A site than in the metal-B site. By using three human melanoma cell lines (HBL, SCL, and BEU), we have studied the catalytic abilities of the human melanogenic enzymes in comparison to those obtained for the counterpart murine enzymes isolated from B16 melanoma. We have found that TRP2 extracted from all cell lines show dopachrome tautomerase activity, although the activity levels in human malignant melanocytes are much lower than in mouse cells. Reconstitution experiments of the human enzyme indicate that TRP2 has Zn at its metal binding-sites. Although mouse tyrosinase does not show DHICA oxidase activity, and this step of the melanogenesis pathway is specifically catalyzed by mouse TRP1, the human enzyme seems to recognize carboxylated indoles. Thus, human tyrosinase could display some residual DHICA oxidase activity, and the function of human TRP1 could differ from that of the murine protein. Attempts to clarify the nature of the metal cofactor in TRP1 were unsuccessful. The enzyme contains mostly Fe and Cu, but the reconstitution of the enzymatic activity from the apoprotein with these ions was not possible.
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Abstract
Melanocytic cells can produce two types of pigment, pheomelanin or eumelanin. We used two types of human melanoma cell lines to explore the regulation of pigmentation by biochemical and enzymatic studies. These two cell lines were previously designated as either pheomelanotic or of mixed type when cultured in a medium rich in cysteine. We analyzed the effects of L-cysteine depletion on melanin synthesis and the involvement of the tyrosinase-related proteins in the production of both eumelanin and pheomelanin. Cultures were exposed to L-cysteine concentrations ranging from 206 to 2.06 microM, and the following parameters were measured: tyrosine hydroxylase activity, intracellular L-cysteine and glutathione concentrations, eumelanin and pheomelanin formation, and tyrosinase-related protein-1 and -2 mRNA levels. Extracellular L-cysteine depletion significantly increased tyrosine hydroxylase activity and promoted both eumelanogenesis and visible pigmentation in both lines. In contrast, pheomelanogenesis was increased only in the pheomelanotic cell line. Whereas eumelanogenesis was apparent upon L-cysteine depletion, tyrosinase-related protein-1 expression was not induced in the pheomelanotic cells, and tyrosinase-related protein-2 expression remained unchanged. Thus, tyrosinase-related protein-1 mRNA expression seems to be concomitant with eumelanogenesis when the L-cysteine concentration is high, but does not appear essential for eumelanogenesis at low L-cysteine concentrations. The mechanisms governing pheomelanin to eumelanin balance are dependent on L-cysteine, glutathione, and tyrosinase-related protein-1 expression, but none of these factors alone appears to be dominant in directing the synthesis of a particular type of melanin.
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Abstract
Tyrosinase is the key enzyme in pigment synthesis, initiating a cascade of reactions which convert the amino acid tyrosine to the melanin biopolymer. Two other tyrosinase-related proteins (TRP) are known, TRP-1 (probably DHICAoxidase) and TRP-2 (DOPAchrome tautomerase). These proteins show about 40% homology, and recent results have indicated that the genes might be derived from a common ancestor. We will discuss recent findings on genomic organization, and on the proteins and their presumed function, which is important for eumelanin synthesis in mouse and man.
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African origin of an intragenic deletion of the human P gene in tyrosinase positive oculocutaneous albinism. Nat Genet 1994; 7:176-9. [PMID: 7920637 DOI: 10.1038/ng0694-176] [Citation(s) in RCA: 86] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Oculocutaneous albinism (OCA) is a genetically heterogeneous hypopigmentation disorder. One of the two major autosomal recessive forms involves the tyrosinase gene (OCA1), while the other form (OCA2) has recently been associated with alterations of the P gene on chromosome 15. OCA2 is about twice as common as OCA1 in African and African-American populations. We now describe an interstitial deletion that removes a single exon of the P gene. In a large family from an inbred population of tri-racial origin, all individuals with OCA2 were found to be homozygous for this allele. Moreover, the same mutant P allele was detected in several unrelated African American individuals with OCA2, but not in Caucasians with OCA2. The detection of the same allele in two unrelated Africans with OCA2 indicates an African origin for this allele.
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Abstract
The aim of the present work was to estimate the effect of intracellular glutathione depletion on melanogenesis in human melanoma cells. We determined tyrosine hydroxylation activity, the rate-limiting step of the pathway, and 14C-melanin formation, an assay reflecting the global eumelanogenic pathway. Intracellular glutathione was depleted by treatment with buthionine-S-sulfoximine, a well-known inhibitor of gamma-glutamylcysteine synthetase. The intracellular depletion of glutathione was substantial after 20 h of incubation with 50 microM buthionine-S-sulfoximine, although a significant effect could be observed after 6 h. Tyrosine hydroxylase activity increased in parallel with glutathione depletion, to reach 160% with respect to the control values during 24 h of buthionine-S-sulfoximine treatment. We have found the response to buthionine-S-sulfoximine to be dose dependent and the two different human cell lines HBL and LND1 to have similar, if not identical, responses. 14C-melanin formation assay revealed even greater activation, up to 400% of the control values. This indicates that glutathione depletion may have two distinct effects: first, a direct one on tyrosinase activity and, second, an effect on the promotion of eumelanogenesis. The stimulation of tyrosine hydroxylase can be explained by a possible inactivation of the enzyme by endogenous thiol compounds rather than by a direct effect of buthionine-S-sulfoximine itself on tyrosinase. The data suggest that thiol compounds may play a role for stimulation of melanogenesis by ultraviolet radiation.
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Abstract
We have investigated the relationship in human cultured normal and malignant melanocytes between the accumulation of mRNAs encoding tyrosinase and tyrosinase-related protein-1 (TRP-1), the activity of tyrosinase and the presence of melanin. Tyrosinase mRNA correlates with tyrosinase activity and with the presence of pheomelanin, eumelanin or both melanin types. In contrast TRP-1 mRNA is only detectable in cells containing eumelanin, which suggests a role for TRP-1 in the eumelanin synthesis pathway.
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