Microscopically it is a 0.8 cm lesion as photo.

Your diagnosis and differential diagnosis.

（镜下病变直径0.8cm，如图。请诊断和鉴别诊断）

名称：图1
描述：图1

 Looks like tubular carcinoma, a well differentiated invasive ductal carcinoma.  It requires >75%(?) tubular formation in neoplastic glands. Lower right hand portion of the photo shows possible low grade DCIS.  The stroma probably represents desmoplastic response to those tumor glands. I talk with uncertain tone "probable, possible, looks like" because a single photomicrograph is a very limited source for a significant diagnosis, i cannnot be very sure. 

abin译：

像小管癌，属于一种分化好的浸润性导管癌。它要求肿瘤性腺体中小管结构>75%（译注，这个标准有争议，有人严格要求100%。WHO认为小管结构达90%作为诊断标准可能较为妥当）。

右下可能为低级别DCIS。间质可能是促结缔组织反应。

 图太少

 The lesion shares the similar morphology. So this photo represents the entire lesion.

abin译：

其他病变的形态与此相似。因此，这一张图代表整个病变。

 Thank above.

will do it tomorrow night

10x smooth muscle myosin heavy chain stain.

P63 stain also shows nuclear stain in the cells surrounding the tubules.

Now you know the diagnosis.

abin译：

图示SMA免疫组化。p63也显示小管周围的细胞核着色。

现在您知道诊断了吧。

This is a typical tubular ca.

Fig 1 20x H&E

Fig 2.10x SMMHC stain

Fig 3. 10x P63 stain

Fig 4. 10x K67, very low proliferative index

Tubular carcinoma (TC)is composed of small angular, oval, and tubular glands in the fibrotic background. Generally it is easy to make diagnosis. However it may be confused with sclerosing adenosis and microglandular hyperplasia (MGH).

MGH glands also lack myoepithelial cells, but basement memberane stain (for example college IV) and S-100 stain are positive. These two stains are negative for TC. Microscopically, MGA is an infiltrative proliferation of small glands in fibrous or fatty stroma. MGA is composed of small uniform and regular glnads containing eosinophilic secretion.

It is not difficult to tell the difference between TC and sclerosing adenosis (SA). However, occasionally SA can be a mimic of TC. When the dx is unsure, stains of myoepithelial markers can be very useful like my first case.

Thank for reading

njwbhuang译：

第15楼提供的四张图，如下。这才是典型的小管癌。

小管癌是由一些小的有角的、卵圆形和小管状腺体组成，包埋于纤维性间质背景中。一般情况下较易诊断，然而它可与硬化性腺病和微腺体增生（MGH）混淆。

MGH中腺体也无肌上皮细胞，但基底膜染色（Ⅳ型胶原）和S-100蛋白染色阳性，而小管癌中则染色阴性。镜下，微腺性腺病（MGA）是小的腺体浸润于纤维或脂肪间质内，腺体较小，大小较一致，腺腔内含有嗜酸性分泌物。

小管癌与硬化性腺病（SA）的鉴别并不困难。然而，偶尔SA可能误诊为小管癌。当诊断不确定时，正如本例一样，肌上皮标记物有助于诊断。

谢谢阅读。

 Thanks a  lot.!

 To the Second floor:

There are no consensus concerning the proportion of tubular structures to establish the dx of TC. Some suggest the different cut-off points 75%, 90%, 100%. New WHO mentioned that for pragmatic reason, a 90% purity requirement offers a practical solution. For my daily practie, I use 100% as cut off point. Otherwise I call invasive ductal carcinoma with (focal) tubular feature. Few percentage of high grade carcinoma may cause poor prognosis. 

In the right side, few ducts show UDH and no ADH present.  

abin译：

关于诊断所需的小管结构的比例，尚未一致，有三种观点75%，90%和100%。新WHO提出90%作为实用标准。

我在日常工作中采用100%的诊断标准。否则我称为浸润性导管癌伴（局灶）小管癌特征。很少比例的高级别癌也可能预后差。

切片右侧一些导管为UDH，没有ADH。

Just released another tubular carcinoma and share with people who love breast pathology.

Slide Key:

H&E 10x

Lymph node 20x

Lymph node 20x ER stain

This is a very low grade tumor of 0.7 cm with Nottingham grade 1. However axillary SNB shows 1 mm micrometastases.

Definition:

Isolated tumor cell: single cells or small clusters of cell not greater than 0.2 mm. （孤立的肿瘤细胞：单个细胞或小簇，不超过0.2mm）

Micrometastases: >0.2 mm to <2 mm. pN1mi （微小转移：>0.2mm 但<2 mm）

Thanks

 Thanks very much for this very challenging case and great discussion.  I have to say that I would also make the diagnosis of invasive tubular carcinoma as well by looking at the first picture.  It appears to have all the features that we use for a tubular carcinoma.  I am interested to know why Dr. Zhao even consider to do the immunostain in the first place. Can you please share with us your diagnostic process and experience. What morphologic features that prompt you to order an IHC? If I don't do the stain, I would make a wrong diagnosis.  It is true that tubular carcinoma is one of the many common pitfalls in breast pathology.  Thanks again.

abin译：

非常感谢提供如此具有挑战性的病例，并有极好的讨论。我一开始也把第一张图诊断为浸润性小管癌了。它似乎具有我们用于诊断小管癌的所有特征。我很想知道，Dr. Zhao为什么第一步会想到做免疫组化。能否请教诊断过程和经验？什么形态特征促使您作IHC？我如果不作IHC，可能会误诊。确实，小管癌是乳腺病理诊断中的许多常见陷阱之一。再次感谢。