No detection of c-kit gene mutations in exons 9, 11, 13 and 17 and low CD117 expression in plaque-stage mycosis fungoides

The growth factor receptor c-kit (CD117) is expressed in immature T-cells and in some advanced forms of mycosis fungoides. c-kit gene mutation results in unrestricted neoplastic proliferation. We aimed to detect by PCR the most frequent exon mutations in seventeen plaque-stage MF patients, in their perilesional skin and in healthy skin donors. We secondarily evaluated CD117 expression by immunohistochemistry in plaque-stage and tumor-stage MF. We detected no mutation in c-kit gene and low CD117 expression was confirmed on atypical cells in one patient. Complete c-kit exon and intron sequences should be assessed and more sensitive sequencing method could be also applied.     

女贞子对黑素细胞的黑素合成、细胞增殖和c-kit基因表达的影响

目的研究女贞子对体外培养的黑素细胞的影响.方法采用免疫印迹法检测酪氨酸酶蛋白(TRP)和酪氨酸激酶受体蛋白(KIT)含量;405 nm比色测定黑素细胞黑素含量;采用细胞数统计和显微镜观察的方法测定细胞毒性和对细胞增殖的影响.结果研究表明女贞子对黑素细胞的增殖和黑素合成有促进作用;对KIT蛋白合成有显著的促进作用.结论女贞子对黑素细胞增殖和黑素合成具有促进作用,该药物治疗白癜风的疗效可能与酪氨酸激酶受体蛋白含量提高相关.     

Psoralen plus ultraviolet A irradiation-induced lentigines arising in vitiligo: involvement of vitiliginous and normal appearing skin

Psoralen plus ultraviolet A irradiation (PUVA therapy) is commonly used for the management of vitiligo in which perifollicular repigmentation is the usual response pattern. However, excessive PUVA therapy may be associated with adverse effects. We report a case of generalized vitiligo that has been extensively treated with topical and systemic PUVA therapy for several years with the development of extensive and widespread stellate and irregularly shaped black and brown macules (lentigines). Interestingly, the lentigines were observed not only in the normally pigmented skin but also within the depigmented lesions that were lacking the perifollicular response pattern. The lesions developed in the exposed and unexposed skin areas. No evidence of skin malignancy was observed clinically and no melanocyte atypia was detected histopathologically. Cryotherapy may be used in the management of the lentigines; however, because of the extent of lesions this was impractical in our case.     

Investigation by in vivo reflectance confocal microscopy: melanocytes at the edges of solar lentigines

In vivo reflectance confocal microscopy (RCM) provides high-resolution, real-time optical sections of the skin in a non-invasive manner, allowing visualization of the skin in its native state. Highly reflective skin components including melanin, collagen and keratin appear bright (white) in RCM images. RCM examination of solar lentigines is known to show features that correlate well with histologic findings such as supranuclear melanin caps, but there are a limited number of reports on melanocyte dendrites. In this study, we utilized RCM to investigate the melanocyte dendricity and distribution within solar lentigines. Seventeen healthy Japanese females who had fairly large solar lentigines on their faces were recruited to join our clinical study, and we examined them by using RCM on their non-lesional areas, and the inside and the outer rim of the lesional areas. As a result, we discovered that dendritic melanocytes were rarely seen in the center of a solar lentigo (SL), but were seen at a very high frequency in the outer rim of a SL. The results suggest that the melanocytes are more active at the edge of a SL, produce more melanin, and often spread their dendrites widely in a horizontal direction. The findings in this report might shed light on the dynamic pathomechanisms of solar lentigines in vivo.     

Multiple Lentigines (Leopard) Syndrome with Chiara I Malformation

This is a case report of multiple lentigines (Leopard Syndrome) with Chiari malformation, i.e. a herniation of the cerebellum into the foramen magnum. This male patient had generalized multiple lentigines since birth, and the lesions spread steadily, involving the scalp but sparing all mucous membranes. Organ system involvements included heart murmur, ocular hypertelorism, and retardation of growth.     

Nodular mastocytosis

Mastocytosis refers to a group of disorders characterized by the pathologic proliferation of mast cells. We present a 70-year-old white man with a rare presentation of nodular mastocytosis, characterized by disseminated nodular lesions, myelodysplastic syndrome, and a c-kit V560G receptor mutation. The patient presented to the clinic after initial presentation 6 months earlier, with ear pruritus, associated hearing loss, and widespread rash.     

Genetic testing of the family with a Carney-complex member leads to successful early removal of an asymptomatic atrial myxoma in the mother of the patient

Carney complex is a rare cardiocutaneous syndrome with an autosomal-dominant inheritance pattern. Apart from its cutaneous manifestations of multiple blue naevi and lentigines, it can involve multiple other organ systems, particularly the heart, where myxoma tumours commonly develop and can potentially lead to serious complications such as cerebrovascular accidents and myocardial infarction. Recently, a specific mutation in the gene encoding the R1-alpha regulatory subunit of cyclic adenosine monophosphate-dependent protein kinase A (PRKAR1alpha) has been discovered and found to be associated with a high risk of developing cardiac myxomas. We report the case of a Carney-complex family member who displayed no observable clinical or cardiac features of the disease but who was found to be positive for the PRKAR1alpha gene mutation on genetic testing. Further evaluation of this patient subsequently led to the discovery of a 3-cm atrial myxoma that had previously been undetected on cardiac assessment. This case highlights the potential benefits of using genetic screening for this disease.     

Generalized lentiginosis in two children lacking systemic associations: case report and review of the literature

Generalized lentigines associated with multiple noncutaneous features, as in the LEOPARD syndrome and the Carney complex, have been well reported in the literature. Reports of patients with generalized lentigines without systemic abnormalities (termed "generalized lentiginosis") are increasing as well. Despite the lack of systemic features, patients with generalized lentigines only should be monitored for further development of other noncutaneous features, especially cardiac anomalies. We present two patients with generalized lentiginosis and propose a working algorithm in the approach to a child with this finding.     

Comprehensive analysis of melanogenesis and proliferation potential of melanocyte lineage in solar lentigines

BackgroundSolar lentigines (SLs) are characterized by hyperpigmented macules, commonly seen on sun-exposed areas of the skin. Although it has been reported that an increase in the number of melanocytes and epidermal melanin content was observed in the lesions, the following questions remain to be answered: (1) Is acceleration of melanogenesis in the epidermis caused by an increased number of melanocytes or the high melanogenic potential of each melanocyte? (2) Why does the number of melanocytes increase?ObjectiveTo elucidate the pathogenic mechanism of SLs by investigating the number, melanogenic potential and proliferation status of the melanocyte lineage in healthy skin and SL lesions.MethodsImmunostaining for melanocyte lineage markers (tyrosinase, MART-1, MITF, and Frizzled-4) and a proliferation marker, Ki67, was performed on skin sections, and the obtained images were analyzed by image analysis software.ResultsThe expression level of tyrosinase to MART-1 of each melanocyte was significantly higher in SL lesions than healthy skin. The numbers of melanocytes in the epidermis, melanoblasts in the hair follicular infundibulum and melanocyte stem cells in the bulge region were increased in SL; however, no significant difference was observed in the Ki67-positive rate of these cells.ConclusionThe melanogenic potential of each melanocyte was elevated in SL lesions. It was suggested that the increased number of melanocytes in the SL epidermis might be attributed to the abnormal increase of melanocyte stem cells in the bulge.     

Fas and c-kit are involved in the control of hair follicle melanocyte apoptosis and migration in chemotherapy-induced hair loss

Chemotherapy alters the structure and function of hair follicle melanocytes. Molecular mechanisms controlling melanocyte responses during chemotherapy-induced hair loss, however, remain largely unknown. Using immunohistology and multicolor confocal microscopy, we show here that cyclophosphamide administration to C57BL/6 mice alters the activity and fate of hair follicle melanocytes. After 24-48 h, hair bulb melanocytes expressing Fas undergo apoptosis. The number of apoptotic follicular melanocytes is significantly reduced (p<0.01) in cyclophosphamide-treated Fas knockout mice compared to wild-type controls, suggesting that Fas signaling contributes to chemotherapy-induced melanocyte death. After 3-5 d, surviving hair bulb melanocytes express c-kit receptor, proliferate, and appear to migrate up the outer root sheath. Tyrosinase-positive and melanogenically active cells then appear in the epidermis. By Western blotting and immunohistochemistry, expression levels of the c-kit ligand, stem cell factor, in skin and epidermis are strongly increased after cyclophosphamide treatment. Cyclophosphamide-induced migration of the hair follicle melanocytes into epidermis is completely abrogated by administration of c-kit neutralizing antibody. These data suggest that chemotherapy induces a complex response in the hair follicle melanocytes, which includes apoptosis, proliferation, and migration. Pharmacologic manipulation of Fas and c-kit signaling pathways might be useful for the correction of skin hyperpigmentation as a side-effect of chemotherapy.     

Familial cases of atypical clinical features genetically diagnosed as LEOPARD syndrome (multiple lentigines syndrome)

Five familial cases exhibited ephelides-like multiple lentigines, and we examined three of them, a mother and two sons. All three patients presented with small dark-brown maculae on the face and neck and electrocardiographic abnormalities. These findings sufficed to fulfill the criteria for LEOPARD syndrome (multiple lentigines syndrome), although they lacked five of seven major clinical features. However, the family members presented with a webbed neck and pectus excavatum, which are more frequently seen in Turner or Noonan syndrome. Histological examination of the lentigines revealed slightly elongated rete ridges, a hyperpigmented basal layer, and melanophages in the papillary dermis. Direct sequencing of the patients' genomic DNA revealed that all three had a consistent missense mutation [c.1403C > T (p.T468M)] in the PTPN11 gene, confirming LEOPARD syndrome with an atypical phenotype. It was suggested that LEOPARD syndrome shows a diverse phenotype but its diagnosis can be verified by mutation analysis.     

皮肤肥大细胞增生症的研究进展

皮肤肥大细胞增生症是肥大细胞增生症中最多见的类型,以肥大细胞在一个或多个器官聚集增生为特点。研究发现编码跨膜受体KIT蛋白的原癌基因c-kit活化性突变是肥大细胞增生症的一个重要机制,对肥大细胞的增殖有重要作用。酪氨酸激酶抑制剂对有c-kit突变的肥大细胞增生症有治疗作用。本文重点介绍了近年来关于皮肤肥大细胞增生症的发病机制及诊断治疗等方面的进展。     

Melanocyte precursors express elastin binding protein and elastin-derived peptide (VGVAPG) stimulates their melanogenesis and dendrite formation

BACKGROUND: In congenital or acquired dermal melanocytosis, attachment of melanocyte with elastic fiber was shown in electron microscopy of unknown biological meaning. We hypothesize elastin-derived peptide may play a role in activating dermal melanocyte precursors. OBJECTIVES: This study was designed to determine: (i) whether melanocyte precursors express elastin binding protein (EBP); (ii) ontogenic expression of EBP and elastin in murine embryonic skin; (iii) the effects of elastin-derived peptide (VGVAPG) on melanocyte precursors. METHODS: Using immunohistochemistry or Western blot to identify EBP on murine embryonic sections, neural crest cell (NCC) primary culture explants, or two melanocyte precursor cell lines, NCCmelb4 and NCCmelan5. NCC explants or cells were treated with VGVAPG to compare its effect on proliferation, dendrite formation, melanosome maturation and tyrosinase mRNA expression of melanocyte precursors. RESULTS: EBP was immunostained on c-kit+ melanocyte precursors. 67kDa EBP protein was immunoblotted on NCCmelb4 and NCCmelan5 cells. EBP was expressed early at embryonic day (E) 9.5, but elastin appeared later at E12.5 skin. VGVAPG increased DOPA-positive cell number and enhanced their dendrite formation in NCC explants. Electron microscopy showed advanced melanosome maturation in NCC explants or cells treated with VGVAPG. VGVAPG enhanced tyrosinase mRNA expression in NCCmelan5 cells. CONCLUSIONS: Melanocyte precursors expressed EBP. VGVAPG stimulated their melanogenesis and dendrite formation. In the developmental journey interaction between elastin and EBP-expressed melanocyte precursors in embryos happened mainly since the stage of tertiary melanoblasts. These findings first provide biological evidences for the interaction between melanocyte and elastic fiber.     

Pigmentary Anomalies in the Multiple Lentigines Syndrome: Is it Distinct from LEOPARD Syndrome?

Abstract: We observed 2 families with 26 individuals affected by multiple lentigines syndrome (MLS). All patients had extensive generalized lentigines, including in the axillary and inguinal regions, diffuse hyperpigmentation, hypopigmented patches, and hyperpigmented patches, many of which appeared clinically to be café au lait spots. Multiple lentigines syndrome should be considered in the differential diagnosis of multiple café au lait spots in children, particularly since the spots are usually present before the lentigines develop and may be clinically indistinguishable from the café au lait spots of neurofibromatosis. No significant non-cutaneous features occurred in the two families with three generations of affected individuals, suggesting that MLS is a distinct entity. However, patients with the noncutaneous abnormalities of the LEOPARD syndrome have been described in families in which most members had pigmentary lesions only. Therefore, patients with multiple lentigines should be evaluated for noncutaneous abnormalities, particularly hearing loss and cardiac anomalies. Similarly, until investigators demonstrate lack of genetic linkage between MLS and LEOPARD syndrome, genetic counseling of patients affected by the cutaneous features of the former should include the potential for noncutaneous features in offspring.     

LEOPARD Syndrome with PTPN11 Gene Mutation Showing Six Cardinal Symptoms of LEOPARD

LEOPARD multiple congenital anomaly syndrome inherited in an autosomal dominant manner. LEOPARD is an acronym for Lentigines, Eletrocardiographic conduction defects, Ocular hypertelorism, Pulmonary valve stenosis, Abnormalities of the genitalia, Retardation of growth, and Deafness. Clinical diagnosis is primarily based on multiple lentigines, typical facial features, and the presence of hypertrophic cardiomyopathy and/or café-au-lait macules. We report a typical case of LEOPARD syndrome with PTPN11 gene mutation associated with lentigines, electrocardiograph abnormality, ocular hypertelorism, pulmonary valve stenosis, growth retardation, and sensorineural hearing loss.     

斑驳病c-kit基因突变检测

目的：检测2例散发斑驳病患儿及其父母c-kit基因的突变情况。方法：收集2例斑驳病患儿及其父母的临床资料,提取其外周血DNA,采用PCR扩增c-kit基因编码区的全部外显子,DNA直接测序,明确突变位点。针对所发现的突变位点以TaqⅠ酶及SmaⅠ酶进行限制性内切酶检测。结果：2例患儿c-kit基因分别于第1862位C→A及第1784位T→C,使密码子GCT→GAT和CTG→CCG,导致Ala621Asp及Leu595Pro突变。2例患儿父母以及50名健康对照者不存在此两种基因突变。结论：Ala621Asp及Leu595Pro均为新生（denovo）突变,此突变是2例散发斑驳病患儿的主要病因。     

Piebald trait: implication of kit mutation on in vitro melanocyte survival and on the clinical application of cultured epidermal autografts

Piebald trait leukoderma results from "loss-of-function" mutations in the kit gene. Correlations between mutation type and clinical phenotype have been reported. However, mutation classification has been mainly based on the clinical features of patients. The aim of this study was to get a better understanding of the pathogenesis of human piebaldism by establishing whether the kit mutation type may affect the in vitro survival/proliferation of patient melanocytes. Overall, the research was finalized to implement the clinical application of the autologous cultured epidermis in the treatment of piebald patients. Seven patients, who were transplanted with autologous in vitro reconstituted epidermis, showed an average percentage of repigmentation of 90.7. Six novel and one previously reported mutations were found and their postulated effects discussed in relation to the clinical phenotype and in vitro behavior of epidermal cells. Although mutation type did not impair repigmentation given by autotransplantation, it was shown to influence the survival/proliferation of co-cultured melanocytes and keratinocytes. In particular, tyrosine kinase domain mutations were found with melanocyte loss and keratinocyte senescence during expansion of epidermal cultures. Results indicate that the clinical application of cultured epidermis in piebald patients may be optimized by investigating mutation functional effects before planning surgical operations.     

HMB-45 recognizes stimulated melanocytes

A monoclonal antibody (HMB-45) was previously reported to bind to melanoma cells, and the junctional component of nevus cells, but not to normal adult melanocytes. We have tested HMB-45 binding in several conditions under which melanocyte stimulation might be expected in adults, i.e. 3 simple lentigines, 2 solar lentigines, 7 recent surgical scars (from re-excision of non-melanocytic tumors), 2 surgical scars from re-excisions of melanomas (after complete primary excisions), 9 hemangiomas from non-sun-exposed skin, 1 basal cell carcinoma, 1 acute ecchymosis, 1 keloid, and 1 dermatofibroma. Positive controls included 6 malignant melanomas and 1 fetal skin sample. Melanocytes were strongly positively stained overlying hemangiomas, within or near recent surgical scars of melanocytic and non-melanocytic tumor re-excisions, near basal cell carcinoma, and in fetal skin. Melanocytes either were not stained or were stained only focally for trace amounts in the normal skin near the new margins of the wide re-excision specimens for melanoma, i.e., at a distance from the scar, in the simple lentigines and in the fibrotic lesions. Thus, HMB-45 is staining an antigen which appears in adult melanocytes during stimulation and in fetal skin, as well as in melanomas. This stimulation is associated with conditions that would have increased vascularity, suggesting a melanocyte response to a plasma factor, or other endothelial cell derived factor. HMB-45 would not be a useful marker for residual melanoma cells in melanoma re-excision specimens.     

Cryotherapy of PUVA lentigines

PUVA lentigines do not subside after discontinuation of photochemotherapy. Cryotherapy with liquid nitrogen was done on a small area in a patient who presented with numerous PUVA lentigines. Five years after this treatment, the PUVA lentigines had not returned. Cosmelically disturbing PUVA lentigines can be treated with cryotherapy.     

A randomized,double‐blind,vehicle‐controlled study of a preparation containing undecylenoyl phenylalanine 2% in the treatment of solar lentigines

Background. Solar lentigines are common, benign, cosmetically disfiguring lesions. Available physical treatments are effective, but they are costly and carry risks of side‐effects. Objective. To evaluate the efficacy and safety of a preparation containing undecylenoyl phenylalanine 2% in the topical treatment of solar lentigines. Methods. In total, 36 patients with solar lentigines of the hands were randomly assigned to apply the active preparation on one side and the vehicle alone on the other side, twice daily for 12 weeks. Patients were evaluated monthly for efficacy and safety. Results. In all, 30 patients (28 women and 2 men; age range 47–75 years) completed the study. The duration of lesions ranged from 8 months to > 10 years. All patients responded partially on the side of the active treatment. Of the partial responders, 19 (63.3%) had moderate improvement and 11 (36.6%) had marked improvement. Improvement was evident from the first follow‐up visit. On the side of the vehicle, 26 remained stable (86.6%) and 4 (13.3%) had partial improvement. There was a significant difference (P < 0.01) in efficacy of the active preparation vs. the vehicle. Using patient assessment ratings, 80% were ‘much more satisfied/more satisfied’ with the result. The reported side‐effects were minor and included erythema and itching or burning on the side of active treatment. Conclusions. Undecylenoyl phenylalanine 2% is a novel depigmenting agent, which possibly acts as an α‐melanocyte‐stimulating hormone antagonist, thus inhibiting melaninogenesis. It achieved a significant lightening of the lesions with minimal side‐effects. Most patients were satisfied with the improvement. Undecylenoyl phenylalanine 2% may represent a safe, effective and inexpensive therapeutic alternative for solar lentigines.