Wood Benjamin A, Harvey Nathan T
*Department of Anatomical Pathology, PathWest, QEII Medical Centre, Nedlands, Australia; and †School of Pathology and Laboratory Medicine, The University of Western Australia, Crawley, Western Australia, Australia.
Am J Dermatopathol. 2016 Jul;38(7):504-9. doi: 10.1097/DAD.0000000000000474.
As ultraviolet radiation is an important aetiological agent in melanoma development, the presence of solar elastosis is an important factor in the assessment of any melanocytic lesion. However, melanocytic naevi are also seen in chronically sun damaged skin, particularly in regions with high levels of ultraviolet exposure and fair skinned populations. It has previously been noted that the relationship of a melanocytic proliferation to elastic fibers in the dermis can be of discriminatory value in the separation of melanoma from melanocytic naevus, in particular, it has been proposed that naevi act as a "sunscreen," which may result in a histological clue that the authors colloquially refer to in practice as "the umbrella sign." The aim of this study was to evaluate the patterns of solar elastosis within and beneath melanocytic proliferations developing in sun damaged skin and to determine the utility of the "umbrella sign" in diagnostic practice. We assessed 81 melanocytic proliferations in sun damaged skin for the presence of an umbrella sign, that was present in 49/53 melanocytic naevi (92%) compared with only 2/28 melanomas (7%, P < 0.05). In addition, entrapped elastotic fibers displaying distinct purple discolouration were identified in 16 melanocytic naevi. This finding was not identified in any of the melanomas. The umbrella sign appears to be a useful clue in the distinction of melanoma from melanocytic naevus in sun damaged skin, although as with all histological features in melanocytic pathology, it requires interpretation within a multifactorial assessment cognizant of potential diagnostic pitfalls.
由于紫外线辐射是黑色素瘤发生发展的重要病因，日光性弹力组织变性的存在是评估任何黑素细胞性病变的重要因素。然而，黑素细胞痣也可见于长期受阳光损伤的皮肤，尤其是在紫外线暴露水平高的地区和皮肤白皙的人群中。此前已经注意到，黑素细胞增生与真皮弹性纤维的关系在区分黑色素瘤和黑素细胞痣方面可能具有鉴别价值，特别是有人提出痣起到“防晒霜”的作用，这可能会产生一种组织学线索，作者在实践中通俗地称之为“伞状征”。本研究的目的是评估在阳光损伤皮肤中发生的黑素细胞增生内部和下方的日光性弹力组织变性模式，并确定“伞状征”在诊断实践中的效用。我们评估了81例阳光损伤皮肤中的黑素细胞增生是否存在伞状征，53例黑素细胞痣中有49例（92%）存在伞状征，而28例黑色素瘤中只有2例（7%）存在伞状征（P<0.05）。此外，在16例黑素细胞痣中发现了呈明显紫色变色的包埋弹力组织纤维。在任何黑色素瘤中均未发现这一现象。伞状征似乎是区分阳光损伤皮肤中黑色素瘤和黑素细胞痣的有用线索，尽管与黑素细胞病理学中的所有组织学特征一样，它需要在考虑潜在诊断陷阱的多因素评估中进行解读。
