Beltraminelli Helmut, Shabrawi-Caelen Laila El, Kerl Helmut, Cerroni Lorenzo
Research Unit of Dermatopathology, Department of Dermatology, Medical University of Graz, Graz, Austria.
Am J Dermatopathol. 2009 May;31(3):305-8. doi: 10.1097/DAD.0b013e31819d3769.
We encountered recently 3 cases with a histopathologic diagnosis of melanoma in situ on sun-damaged skin (male = 2, female = 1; median age: 59 years; range: 52-60 years). The diagnosis was based mainly on the finding of actinic elastosis in the dermis and increased number of melanocytes in the epidermis and was confirmed by strong positivity for Melan-A in single cells and in small nests ("pseudomelanocytic nests"), located at the dermoepidermal junction. Indeed, examination of slides stained with hematoxylin and eosin revealed the presence of marked hyperpigmentation and small nests of partially pigmented cells at the dermoepidermal junction, positive for Melan-A. The histologic and especially the immunohistochemical features were indistinguishable from those of melanoma in situ on chronic sun-damaged skin. In addition, a variably dense lichenoid inflammation was present. Clinicopathologic correlation, however, showed, in all patients, the presence of a lichenoid dermatitis (phototoxic reaction, 1 case; lichen planus pigmentosus, 1 case; and pigmented lichenoid keratosis, 1 case). Our cases clearly show the histopathologic pitfalls represented by lichenoid reactions on chronic sun-damaged skin. Immunohistochemical investigations, especially if performed with Melan-A alone, may lead to confusing and potentially disastrous results. The unexpected staining pattern of Melan-A in cases like ours raises concern about the utility of this antibody in the setting of a lichenoid tissue reaction on chronic sun-damaged skin. It should be underlined that pigmented lesions represent a paradigmatic example of how immunohistochemical results should be interpreted carefully and always in conjunction with histologic and clinical features.
我们最近遇到3例组织病理学诊断为日光损伤皮肤原位黑色素瘤的病例（男性2例，女性1例；中位年龄：59岁；范围：52 - 60岁）。诊断主要基于真皮层光化性弹力组织变性以及表皮层黑素细胞数量增加的发现，并通过位于真皮表皮交界处的单个细胞和小巢状（“假黑素细胞巢”）中Melan - A呈强阳性得以证实。实际上，苏木精和伊红染色切片检查显示真皮表皮交界处存在明显色素沉着以及部分色素沉着细胞的小巢状结构，Melan - A呈阳性。组织学特征，尤其是免疫组织化学特征与慢性日光损伤皮肤原位黑色素瘤难以区分。此外，还存在不同程度的致密苔藓样炎症。然而，临床病理相关性分析显示，所有患者均存在苔藓样皮炎（光毒性反应1例；色素性扁平苔藓1例；色素性苔藓样角化病1例）。我们的病例清楚地显示了慢性日光损伤皮肤上苔藓样反应所代表的组织病理学陷阱。免疫组织化学检查，特别是仅使用Melan - A进行检查时，可能会导致混淆且可能带来灾难性后果。在我们这样的病例中Melan - A意外的染色模式引发了对于该抗体在慢性日光损伤皮肤苔藓样组织反应背景下实用性的担忧。应当强调的是，色素性病变代表了一个典型例子，说明免疫组织化学结果应如何始终结合组织学和临床特征进行仔细解读。
