DART BOARD专栏读者来信和回复

读者来信

尊敬的Daniel Kopans教授：

在乳腺影像（超声、乳腺X射线摄影和乳腺MR）诊断报告中，经常会有乳腺增生的提示或诊断，但是BI-RADS分类指南里没有提到这个概念，对于乳腺组织增生，您是怎么看的？

您忠实的，

**医生

Dr. Kopans回复译文

关于“乳腺组织增生”

“乳腺组织增生”不是影像学的专业术语，“增生”是病理学家在显微镜下观察时使用的术语，它基本就意味着通常在导管内为单层的上皮细胞变为多层。我不知道有什么影像学的发现可以准确地对应上这种病理组织学上的发现。

我猜一些放射科医生可能是使用“增生”这个术语来描述X光片上的致密乳腺组织，这是不合适的。乳房中有许多脂肪（脂肪组织）。乳房中也有支撑乳房和腺体网络的结缔组织，它们以Astley Cooper爵士命名为Cooper韧带，其含量分布差异很大。

乳腺导管（排列着上皮细胞）开口于乳头，逐级向下形成分支，最后导管的末端汇入小叶，乳腺小叶类似一串串中空的葡萄，这些细胞在哺乳期分泌乳汁。小叶、导管和支撑结构的纤维组织对X射线衰减是相同的（与水密度一致）。因此，除非将造影剂注入导管并充满小叶，否则很难区分导管组织和纤维结缔组织。所有这些含水组织一起被称为“致密乳腺组织”。

由于癌组织与导管、小叶（腺体）和纤维组织的Ｘ射线衰减相同，因此除非它们含有钙化（微钙化），或结构扭曲，或被脂肪与其它水密度一致的组织分隔开，否则癌组织就很可能被乳腺的致密组织所隐匿。过去，放射科医生曾将致密组织描述为“增生”，但在美国我们已经放弃了这一术语，简单称之为“致密组织”。

Dr. Kopans回复原文

WITH REGARD TO "BREAST TISSUE HYPERPLASIA"

Erplasia” is not valid imaging terminology. “Hyperplasia” is a term that the pathologist uses when looking through a microscope.It basically means that the epithelial cells that usually form a single layer of cells lining the inside of the ducts are forming multiple layers.I am not aware of any valid imaging correlation that can be reliably correlated with this histological finding. 

I suspect that some radiologists are using this term, inappropriately, to describe radiographically dense breast tissue. As you know, the breast contains large amounts of fat (adipose tissue).  There is a wide variation in the normal amounts of connective tissue (regular and specialized) that support the breast and the duct network. The large amounts of regular connective tissue are named after Sir Astley Cooper and called “Cooper’s Ligaments”. 

If we start at the nipple and enter a duct opening, the tube (lined with epithelial cells) will branch back into the breast until we reach the end of the duct and we enter the lobule which is like a hollow bunch of grapes. These cells secrete milk during lactation. The lobules, ducts, and fibrous supporting structures all have the same X-ray attenuation (water density). Consequently, unless you inject a contrast agent into the ducts and fill them back to the lobules, it is rarely possible to differentiate ductal tissue from fibrous connective tissue. All these water containing tissues together are what have been called “dense breast tissue”. 

Since cancers are the same X-ray attenuation as the ducts, lobules (glands), and fibrous tissue, unless they contain calcifications (microcalcifications), or cause architectural distortion, or are set off from the other water density tissues by fat, cancers can be hidden by the dense tissues of the breast.  In the past, radiologists used to describe the dense tissues as “hyperplastic”, but we have dropped this terminology in the U.S. and it is now referred to simply as “dense tissue”.