Common acquired melanocytic nevi, dysplastic melanocytic nevi and malignant melanomas: an image analysis cytometric study

We used computerized image analysis cytometry in analyze 10 melanocytic lesions from each of the following categories: common acquired nevi, melanocytic nevi with architectural features of dysplasia, dysplastic melanocytic nevi (DMN) with slight atypia, DMN with moderate atypia, DMN with severe atypia, and superficial spreading melanomas. The nuclei of at least 50 consecutive nevomelanocytes in the most atypical zones were digitized at ×1000 under oil immersion, without knowledge of diagnosis by one observer. Grading of atypia was based on current practices as described in the literature. The results showed significant differences ( p < 0.05) in nuclear area and standard deviation of nuclear area between melanoma and DMN with severe atypia, and between DMN with severe atypia and all other categories of nevi. There were no differences among any lesions with respect to nuclear shape. No differences in nuclear area were found among DMN with moderate, or slight atypia, nevi with features of dysplasia, and typical nevi. These results show for the first time objective distinction of low-grade (slight-moderate atypia), and high-grade or severe atypia in pre-malignant nevomelanocytic lesions of the skin.     

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.     

Histogenesis of congenital and acquired melanocytic nevi based on histological study of lesion size and thickness

The histogenesis of melanocytic nevi is poorly understood. It is important to determine the differences and similarities in histogenesis between congenital and acquired nevi. To clarify the histogenic differences between acquired melanocytic nevi (AMN) and congenital melanocytic nevi (CMN), diameter and depth of nevus cells (tumor thickness) were examined in histological specimens from 80 cases of CMN and 71 cases of AMN, and these nevi were classified according to Mark's pathological CMN criteria. In all cases, giant CMN nevus cells were found in the lower marginal portion of excised specimens. The mean diameter and lesional thickness were significantly higher in CMN than in AMN. AMN diameter showed a significant correlation (r = 0.567, P < 0.05) with lesional thickness, while no such relation was observed in CMN. In addition, a significant correlation between lesion diameter and thickness was observed in small (<10 mm) non-Mark's type CMN (r = 0.626, P < 0.05). CMN may be classified into three subtypes: (i) caused by increased proliferation of melanoblasts during the course of migration from the neural crest to the epidermis; (ii) proliferation of nevus cells after arrival at the epidermis, and nevus cell distribution affected by adnexa and dermal differentiation; and (iii) arising after completion of skin development before birth.     

巨大先天性色素痣皮损处出现白毛1例

报告巨大先天性色素痣皮损处出现白毛1例。患者男,34岁。患巨大先天性色素痣34年。2年前发现胸部色素痣上部分胸毛变白,患者无白瘢风、晕痣及皮肤色素减退。先天性巨大色素痣上出现白毛值得研究。     

婴幼儿先天性色素痣126例临床及病理特征分析

【摘要】 目的 总结婴幼儿先天性色素痣的临床及病理特征。方法 回顾性分析2015年1月至2020年1月在西京皮肤医院确诊的126例婴幼儿先天性色素痣患儿的临床及病理资料。计数资料比较采用χ2检验。结果 126例婴幼儿先天性色素痣患儿中,男68例,女58例;86.5%的患儿出生即有皮损;57.9%就诊年龄2 ~ 3岁。皮损发生部位包括头面部（76例,60.3%）、躯干（24例,19.1%）、四肢 （26例,20.6%）。36例（28.6%）为先天性小痣,68例（54.0%）为M1型中型痣,13例（10.3%）为M2型,9例（7.1%）为巨痣。121例（96.0%）皮损单发,5例（4.0%）多发,44例（34.9%）痣伴粗毛,15例（11.9%）伴丘疹/增生性结节,6例（4.8%）有卫星灶。病理亚型包括混合痣120例（95.2%）、皮内痣4例（3.2%）和交界痣2例（1.6%）。38例（30.1%）镜下皮损深度< 1 mm,61例（48.4%）1 ~ 2 mm,25例（19.8%） > 2 mm,45例（35.7%）浸润至皮下脂肪层或更深。126例色素痣皮损中,常见病理特征包括痣组织成熟现象（100%,不包括2例交界痣）,角质层色素颗粒（42.1%）,分布紊乱/不对称（63.5%）,表皮痣细胞散在分布（72.2%）和呈Paget样扩散（53.2%）,真皮可见噬黑素细胞（56.4%）,痣细胞沿毛囊皮脂腺分布（65.1%）等。特殊病理特征包括痣细胞嵌入血管/淋巴管腔内（33.3%）、痣细胞松解（35.7%）、纤维瘤样改变（19.8%）、累及立毛肌（24.6%）、肥大细胞浸润（23.8%）等。不同临床表现的婴幼儿先天性色素痣病理模式：浸润深度 > 2 mm、角质层色素颗粒和角质层柱状色素颗粒在巨痣中的发生率明显高于其他大小皮损（χ2 = 7.93、10.76、5.89,均P < 0.05）;浸润深度 > 2 mm、表皮海绵水肿伴痣细胞散在分布、痣细胞巢沿毛囊皮脂腺分布、纤维瘤样改变、肥大细胞浸润在伴有粗毛皮损中的发生率明显高于不伴粗毛者（χ2 = 28.29、8.11、6.22、7.92、8.19,均P < 0.01）;表皮痣细胞呈Paget样扩散、痣细胞有异型性在伴丘疹/增生性结节的皮损中的发生率高于不伴丘疹增生性结节的皮损（χ2 = 4.92、6.30,均P < 0.05）。结论 婴幼儿先天性色素痣的临床及组织病理具有独特性,细胞常见不典型性,确诊及治疗选择需要密切结合临床与病理特征。     

Molluscum contagiosum arising in a melanocytic congenital nevus

Molluscum contagiosum within a congenital melanocytic nevus has rarely been reported. We report a 6‐year‐old child with molluscum contagiosum infection arising within an intermediate melanocytic congenital nevus of the thigh, associated with itching and occasional bleeding. Dermoscopy lead to the correct diagnosis, but histologic confirmation with shave biopsy was performed to reassure the parents and allow mechanical removal of the lesions using curettage.     

Rhabdomyosarcoma arising in a congenital melanocytic nevus.

A variety of malignancies have been reported to arise within congenital melanocytic nevi, most commonly malignant melanoma, but rarely rhabdomyosarcoma, liposarcoma, and malignant peripheral nerve sheath tumor as well. There have been only three documented cases of rhabdomyosarcoma arising within congenital melanocytic nevi: two embryonal rhabdomyosarcomas and one mixed liposarcoma and rhabdomyosarcoma. One of these cases was also associated with neurocutaneous melanosis. We report a fourth case of rhabdomyosarcoma originating from a congenital melanocytic nevus. A 4-year-old girl presented with a large ulcerated nodule that developed within a hairy congenital nevus on her left gluteal and sacral regions. Her parents refused postoperative adjuvant therapy, and she died 13 months after surgical excision. Histologic sections showed a lesion with two distinct components. There was an expansile proliferation of pleomorphic cells within a fibromyxoid stroma. The neoplastic cells were spindled, and some had abundant eosinophilic globular cytoplasm with occasional cross-striations characteristic of rhabdomyoblasts. They strongly expressed desmin and myoglobin and were negative for S-100 protein and HMB-45. The tumor merged with an adjacent congenital melanocytic nevus characterized by a proliferation of uniform nonatypical melanocytes. The finding of both rhabdomyoblastic and melanocytic differentiation within the same lesion lends support to the hypothesis of their derivation from common pluripotential stem cells or neural crest cells.