Expression of AID in malignant melanoma with BRAFV600E mutation

BRAF‐activating somatic mutations often exist in malignant melanoma. The underlying molecular mechanism of somatic BRAF mutation inductions remained to be clear. Activation‐induced cytidine deaminase (AID), a member of a cytidine deaminase family, and APOBEC3B induce somatic mutations and recently have been indicated to be involved in the pathomechanism of several kinds of cancers. The aim of this study was to explore the expression level of AID and APOBEC3B in BRAF‐mutation‐ containing malignant melanoma. Immunohistochemical study demonstrated that 9 of 10 malignant melanomas with high AID expression had BRAF^V600E mutation. Eight of them developed multiorgan metastases or multiple lymph node metastases afterwards. Although the size of the patient panel was small, the results indicate that there might be an association between AID expression and BRAF mutation in melanoma.     

BRAF(V600E)基因突变与儿童先天性色素痣的增殖活性及组织病理学特征的相关性研究

目的:明确先天性色素痣(congenital melanocytic nevi, CMN)中BRAF(V600E)基因突变对其增殖活性和组织病理学的影响。方法:回顾分析2018年12月至2020年12月我院皮肤科诊治的185例CMN患儿,所有患儿均进行基因检测、病理检查和Ki67免疫组化检测。根据基因检测结果是否存在BRAFV600E突变,将入选患儿分为突变组和对照组,然后再根据性别、年龄、皮损大小和皮损部位进行配对后进一步研究。结果:突变组Ki67指数、痣细胞累及深度、痣细胞巢个数、痣细胞巢大小与对照组比较差异均有统计学意义(均P<0.05)。与BRAF V600E阴性的CMN相比,BRAF(V600E)阳性CMN通常在表真皮交界部位形成黑素细胞巢,且巢较大。痣细胞累及深度和痣细胞巢个数与Ki67指数之间成正相关(均P<0.05)。结论:BRAF(V600E)基因突变使CMN的增殖活性明显升高,并对其组织病理学有特殊的影响。     

BRAFV600E突变基因对人黑素瘤细胞侵袭能力影响的研究

目的 探讨BRAFV600E突变基因对黑素瘤细胞侵袭能力的影响。方法　用构建成功的质粒载体转染人黑素瘤细胞株A375,在体外干扰BRAFV600E突变基因,用Transwell小室检测肿瘤细胞侵袭能力,用明胶酶法检测基质金属蛋白酶-2（MMP-2）的变化,采用RT-PCR和Western印迹检测MMP-2和血管内皮细胞生长因子（VEGF）mRNA和蛋白表达。结果　特异性短发卡RNA抑制人黑素瘤细胞MMP-2和VEGF mRNA和蛋白的表达,MMP-2 mRNA和蛋白表达分别减少35%和80%,VEGF则减少45%和14%。转染特异性质粒的黑素瘤细胞穿过Metrigel的数目下降69%。结论 BRAFV600E突变增强黑素瘤细胞的侵袭能力,特异性shRNA可以使瘤细胞的侵袭性下降。     

The association of BRAF V600E gene mutation with proliferative activity and histopathological characteristics of congenital melanocytic nevi in children

BackgroundA lot of congenital melanocytic nevi (CMN) carry the somatic mutation in the oncogene BRAF V600E. But the detailed histopathologic characteristics and the proliferative activity of CMN with BRAF V600E gene mutation have not been systematically documented.ObjectiveTo identify the proliferative activity and histopathological features correlating them with BRAF V600E gene mutation status in CMN.MethodsCMN were retrospectively identified from the laboratory reporting system. Mutations were determined by Sanger sequencing. The CMN were divided into a mutant group and control group according to whether there was BRAF gene mutation and were strictly matched according to gender, age, nevus size, and location. Histopathological analysis, analysis of Ki67 expression by immunohistochemistry and laser confocal fluorescence microscopy were performed.ResultsThe differences in Ki67 index, the depth of nevus cell involvement and the number of nevus cell nests between the mutant group and the control group was statistically significant, with p-values of 0.041, 0.002 and 0.007, respectively. Compared with BRAF V600E negative nevi, BRAF V600E positive nevi often exhibited predominantly nested intraepidermal melanocytes, and larger junctional nests, but the difference in this data sets were not statistically significant. The number of nests (p = 0.001) was positively correlated with the proportion of Ki67 positive cells.Study limitationsA small sample of patients were included and there was no follow-up.ConclusionsBRAF V600E gene mutations were associated with high proliferative activity and distinct histopathological features in congenital melanocytic nevi.     

BRAFV600E and KIT immunoexpression in early-stage melanoma

Melanoma is widely known as the most lethal skin cancer. Specific tumor-related mortality can be significantly reduced if diagnosis and treatment are properly performed during initial phases of the disease. The current search for bio-markers in early-stage melanomas is a high-priority challenge for physicians and researchers. We aimed to assess the immunoexpression of BRAFV600E and KIT in a case series consisting of 44 early-stage melanomas. Formalin-fixed paraffin-embedded samples were systematically evaluated using a semi-quantitative method based on scores of percentage and intensity for immunostained tumor cells. We observed significant concordance between BRAFV600E and KIT immunoexpression in thin invasive melanomas. Our findings corroborate previous evidence showing abnormal expression of proteins associated with MAPK intracellular signaling pathway in early-stage melanomas.     

A histologic comparison of congenital and acquired nevomelanocytic nevi

A reliable microscopic differentiation of nevomelanocytic nevi (NMNs) as congenital or acquired would be useful in defining a histogenic relationship between cutaneous melanoma and congenital NMN. In order to delineate histologic differences between congenital NMN and acquired NMN, a standardized assessment was conducted blindly, using a sample of consecutive surgical specimens of NMN submitted to a children's hospital pathology file. Despite significant histologic differences between congenital NMN and acquired NMN, the lack of a reliable prevalence rate for the proportion of congenital NMNs among all NMN specimens submitted for pathologic examination precludes a precise estimate of predictive value for diagnosing a given NMN as congenital or acquired based on histologic features alone. The results of this study can be used neither to support nor to refute a histologic association between cutaneous melanoma and congenital NMN.     

Quantitative studies of congenital and acquired nevus cell nevi]

A total of 576 melanocytic naevi routinely excised within 1 year were analysed histologically and epidemiologically without knowledge of the clinical diagnosis. Classification into congenital melanocytic naevi (CMN, n = 82) and acquired melanocytic naevi (AMN, n = 494) was performed on the basis of the clinical history. Only a few CMN, and also some AMN, reached the lower dermis and the subcutis. An affinity of naevus cells (NC) for skin appendages was observed significantly more often in CMN than in AMN. However, no type of skin appendages was exclusively infiltrated by NC of CMN. The NC affinity for different types of skin appendages in a single naevus was characteristic of CMN. A subepidermal zone poor in NC was seen more often in CMN. The broad horizontal layer of NC within the upper dermis was rather rare in both types of melanocytic naevi. In spite of significant histological differences between CMN and AMN, the specificity and sensitivity of each criterion proved to be too low for a reliable histological diagnosis of CMN.     

Lack of BRAF(V600E) mutations in giant congenital melanocytic nevi in a Chinese population

Giant congenital melanocytic nevi (CMNs) are at an increased risk for malignant transformation. To explore the mutation frequencies of BRAF(V600E) (V-raf murine sarcoma virus oncogene homolog B1) and NRAS (neuroblastoma ras viral oncogene homolog) codon 61 in CMNs of Chinese, we selected 55 paraffin-embedded tissue blocks, including 37 cases of medium CMNs (1.5-20cm) and 18 cases of giant CMNs (>20 cm). Direct sequencing was performed to detect the BRAF(V600E) and NRAS codon 61 mutations. The BRAF(V600E) mutations were detected in 9 of 55 nevi (16.4%). In medium CMNs, 9 of 37 BRAF(V600E) mutations (24.3%) were detected. Notably, in giant CMNs, no BRAF(V600E) mutations were found. The difference between these frequencies is statistically significant (P = 0.0231). NRAS codon 61 mutations were detected in 13 of 55 nevi (23.6%), including 10 of 37 medium CMNs (27.0%) and 3 of 18 giant CMNs (16.7%). Additionally, the BRAF(V600E) and NRAS codon 61 mutations did not coexist in the same sample. Finally, we found that the NRAS codon 61 mutation was significantly related to the amount of sun exposure (0 of 18 CMNs from sites of intermittent sun exposure and 13 of 36 CMNs from sites of chronic continuous sun exposure, P = 0.0024). The paradoxically higher incidence of BRAF(V600E) mutations in medium-sized compared with giant CMNs suggests that the presence of the BRAF(V600E) mutation may play different roles between medium and giant CMNs in melanocytic tumorigenesis.     

G1 cell cycle regulators in congenital melanocytic nevi. Comparison with acquired nevi and melanomas

Background:  Congenital nevi are one of the known risk factors for the development of melanoma. However, the magnitude of the risk for both large and small congenital nevi is controversial.
Methods:  In order to elucidate the behavior of congenital nevocytes and to define any possible similarities or differences with common nevi and melanomas, we investigated the expression of Ki-67, Rb, p16, cyclin D1, p53 and p21/Waf-1 in 41 congenital nevi, 16 melanomas and 20 acquired common nevi by immunohistochemistry.
Results:  Congenital nevi highly expressed p16 (81.82 ± 9.98) but showed limited, if any, reactivity for Ki-67 (1.34% ± 0.89), Rb (0.76% ± 0.94), cyclin D1 (0.21% ± 0.29), p53 (0.54% ± 0.93) and p21 (0.0609% ± 0.32). No statistically significant difference was found between giant and nongiant congenital nevi and between congenital and common nevi for any of the markers. The expression of p16 was significantly higher in congenital nevi than in melanomas (p < 0.0001). On the contrary, the expression of Ki-67, p53, p21, Rb and cyclin D1 was significantly higher in melanomas (p < 0.0001).
Conclusion:  Our data regarding the immunohistochemical expression of Rb, p16, p53, cyclin D1 and Ki-67 in congenital nevi indicate that either the alteration of their expression is not an initiating event in melanoma formation or, alternatively, congenital melanocytic nevi may not be the first step in malignant transformation.     

The histology of "congenital features" in early acquired melanocytic nevi

To test the specificity of certain histologic features claimed to be frequent in congenital melanocytic nevi, 66 of 313 consecutive newborn infants without congenital nevi (verified by perinatal examination) were addressed in a questionnaire 2 1/2 years after birth. Fifty children with acquired melanocytic nevi were reexamined clinically and biopsies were performed in 15. Congenital features were found in seven biopsy specimens from the indubitably acquired melanocytic nevi. These nevi were larger and more speckled in color than melanocytic nevi without "congenital features." It is concluded that the histologic features said to be specific for congenital nevi are, in fact, not specific. The possible relationship between these features and an increased melanoma risk cannot be refuted by the present study, but the risk of misinterpretation based on congenital features as the sole criterion in the prediction of the potential malignancy of melanocytic nevi is real.     

Langerhans cell histiocytosis and Erdheim‐Chester disease,both with cutaneous presentations,and papillary thyroid carcinoma all harboring the BRAFV600E mutation

Langerhans cell histocytosis (LCH) and Erdheim‐Chester disease are two rare histiocytic disorders. Their occurrence in the same patient is more infrequent, but has been described. We report a case of a 38‐year‐old woman who presented with a diagnosis of single system cutaneous LCH. Subsequently, she developed multiple papules on her extremities consistent with a non‐LCH xanthogranuloma type lesion. BRAF^V600E mutation immunostain, VE1 was positive in the skin lesion, which was confirmed by molecular polymerase chain reaction (PCR) studies, initiating a complete systemic workup for Erdheim‐Chester disease. Systemic involvement was confirmed with bilateral sclerotic bone lesions and retroperitoneal and pelvic fibrosing disease. She was also found to have a BRAF^V600E mutation positive papillary thyroid carcinoma. New suspicious cutaneous lesions presenting in patients with a history of LCH need to be biopsied. A BRAF^V600E mutation in a non‐LCH histiocytic lesion with a xanthogranuloma phenotype (CD163/CD68/CD14/fascin/Factor 13a) should prompt an Erdheim‐Chester disease workup. This is a unique case of a woman with BRAF^V600E mutation positive Erdheim‐Chester disease and cutaneous LCH, while also being, to our knowledge, the first reported case in the English literature of it occurring in a patient with a BRAF^V600E mutation positive papillary thyroid carcinoma.     

On the development of neurocutaneous units--implications for the histogenesis of congenital, acquired, and dysplastic nevi

This study of spontaneous abortions and fetal deaths in utero used immunostains to evaluate the structure of developing cutaneous nerves. Melan-A immunostains were also used to screen 25 cases of grossly normal fetal skin for occult fetal nevi. Discrete portions of epidermis were generally supplied by branches emanating from regularly spaced deep cutaneous nerves, producing a wedge shape, interpreted as neurocutaneous units (NCU). Deeper nerves embraced broader portions of epidermis. Some nerves ran parallel to epidermis, especially near the superficial vascular plexus at the junction of superficial and deep dermis. Nerve sheath stem cells in each NCU may supply the melanocytes needed by the corresponding portion of epidermis. Transformed nerve sheath stem cells may lead to formation of occult prenatal nevi, whose histology and histogenesis may best be understood in terms of NCUs. In particular, the size and shape of a nevus may be largely determined by its NCU of origin. Six fetal nevi were detected, and 3 occult lumbosacral Mongolian spots; all in deep dermis, no later than the middle of the second trimester, mainly with a pattern of singly dispersed deep dermal melanocytes. These findings suggest that congenital (prenatal) nevi begin as intradermal nevi. In addition to explaining congenital nevi, these findings have implications for the histogenesis of acquired (postnatal) nevi and dysplastic nevi.