College of Medicine, Medical University of South Carolina, Charleston, South Carolina, USA.
Department of Dermatology and Dermatologic Surgery, Medical University of South Carolina, Charleston, South Carolina, USA.
J Cutan Pathol. 2024 Apr;51(4):306-310. doi: 10.1111/cup.14577. Epub 2023 Dec 20.
Diffractive microscopy creates contrast within samples that are otherwise uniform under bright light. This technique can highlight subtle differences in refractive indices within birefringent samples containing varying amounts of mature collagen. Dermatofibroma (DF) and dermatofibrosarcoma protuberans (DFSP) possess differences in their mature collagen content and, therefore, may be distinguishable using diffractive microscopy.
Two hundred forty-two DF and 85 DFSP hematoxylin-eosin (H&E)-stained specimens were analyzed using diffractive microscopy. Data regarding the distribution pattern and strength of refractility was recorded.
DFSP was more frequently found to be focally, weakly, or non-refractile (82.9%; n = 68) under diffractive microscopy, while DF more often showed diffusely bright refractility (52.9%; n = 128). DFSP samples with diffuse refractility in portions of the lesion (17.1%; n = 14) also exhibited a unique checkerboard pattern distinct from that which was seen in DF samples.
The absence of diffuse refractility was more closely associated with DFSP, as was the presence of a unique checkerboard diffraction pattern. Despite high sensitivity (Sn = 82.9%), absent refractility was not a specific test (Sp = 52.9%), with 47.1% (n = 114) of DF samples sharing this feature. The distinction between DF and DFSP is often diagnosed using H&E alone. In difficult cases, examination of collagen under diffractive microscopy may be useful in distinguishing DFSP from DF and provide an alternative cost-effective tool to immunohistochemical staining.
衍射显微镜在明亮的光线下使原本均匀的样本产生对比度。该技术可以突出双折射样本中不同成熟胶原蛋白含量的折射率差异。 皮肤纤维瘤 (DF) 和隆突性皮肤纤维肉瘤 (DFSP) 的成熟胶原蛋白含量存在差异，因此可以使用衍射显微镜将它们区分开来。
对 242 例 DF 和 85 例 DFSP 苏木精-伊红 (H&E) 染色标本进行衍射显微镜分析。记录关于折射分布模式和强度的数据。
在衍射显微镜下，DFSP 更常呈现局灶性、弱性或非折射性 (82.9%；n=68)，而 DF 更常表现为弥漫性明亮折射性 (52.9%；n=128)。病变部位弥散折射的 DFSP 样本 (17.1%；n=14) 也表现出独特的棋盘状图案，与 DF 样本不同。
弥漫性折射的缺失与 DFSP 更为密切相关，独特的棋盘状衍射模式也是如此。尽管具有高灵敏度 (Sn=82.9%)，但无折射性不是特异性测试 (Sp=52.9%)，47.1%（n=114）的 DF 样本具有此特征。DF 和 DFSP 的区别通常仅通过 H&E 进行诊断。在困难的情况下，使用衍射显微镜检查胶原蛋白可能有助于将 DFSP 与 DF 区分开来，并提供一种替代的具有成本效益的免疫组织化学染色工具。
