Lower Power: Generally, typical tubular carcinomas show angular and irregular glands with open lumens in desmoplastic stroma, such as my previous two cases. Sclerosing adenosis can also exhibit varying numbers of round, oval, or angular glands with open lumen. However the findings of open lumen often are not obvious.

High power: The nuclei of TC are often  round and uniform, but not for SA.

Please remember that breast bx, skin malanoma, and pap test are the top three for lawsuit. Unfortunately  I am a gyn/breast apthologist and need to deal with the two areas of the three every day. Anyway, You have to think over before you release any malignant case. 

Hope it can help. Thnaks.

abin译：小管癌和硬化性腺病的鉴别要点
低倍：成角和不规则的腺体，管腔开放，促结缔组织增生性间质，正如我已经上传的两个病例。硬化性腺病（SA）也表现为不同数量的圆形或卵圆形或成角腺体，管腔开放。然而，开放的管腔通常不明显。
高倍：小管癌的核通常圆而一致，而SA不是这样。
请记住，乳腺活检，皮肤恶黑，和宫颈细胞学引起的诉讼最多。不幸得很，我从事妇科/乳腺病理，每天都需要处理三者中的两个。总之，发出恶性诊断之前，一定要再三推敲。
希望有帮助。谢谢。

译文：这是典型的小管癌。

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。

 Thank all of you for reading the case and writing your diagnosis here. Most of you have the correct or almost right interpretation or differential diagnosis.

This is a microglandular adenosis  (MGA) case. The main differential dx contain tubular carcinoma (TC) and other adenosis and its variants. The diagnosis is not very difficult based on the morphology if you see few cases already. Histologically, MGA consists small round glands with open lumens, distributed mostly randomly in a hypocellular dense collagenous or fatty stroma. The glands are lined by a single layer of (flat to) uniform cuboidal epithelial cells and completely invested by a basement membrane (TC with no BM). The Lumen contains PAS+ eosinophilic secretion. You should make the dx if you know these morphologic features well. Please compare the morphologic features of this case with that of my above TC cases.

IHC stains can help you. I summaried a brief table below.

*Collagen IV, laminin, reticulin

Very glad to see that some of you have noted the presense of cellular atypia. Focal areas (last 4 photos) show varied gland configuration or irregularity of the glands. Some glans lack secretion and the lumens are obscured by celluar prolifearion. The cells demonstrate mild-moderate nuclear pleomorphism and prominent nucleoli. So the case was dianosed MGA with focal atypia or atypical MGA (AMGA).

MGA is an extremely rare benign breast lesion. 108 cases were originally diagnosed as MGA in M.D Anderson Cancer Center (one of the largest cancer center in the US) from 1983 to 2007. Of the 108 cases, 65 cases had available  materials for review. 11 of 65 cases qualified to have MGA component. Myoepithelial layers was detected in other 54 cases and they were reclassified as adenosis.  Now you know the true MGA case is rare and rare. The hospital I currently work is one of the largest gyn and breast center in the US. Only one MGA case was diagnosed in the past three years. The current case is the one when I worked at AFIP.

The lesion is spectrum of glandular proliferations ranging from uncomplicated MGA to MGA with atypia to MGA associated carcinoma (MGACA). For difficult cases IHC stains for Ki67 and p53 can be helpful.

Ki67: MGA <3%; AMGA 5-10; MGACA>30%

p53: MGA<3%; AMGA 5-10%; MGACA>30%

I think the percentage is just for reference and histologic features are the key for diagnosis.

Useful reference:

1. Khalifeh IM etal. Clinical, histopathologic, and immunihistochemical features .... Am J Surg pathol 2008;32:544-552.

2. Koenig C et al. Carcinoma arising in microglandular adenosis: an immunohistochemical analysis....Int J Surg Pathol 2000;8:303-315.

Just came back from China and feel tired. I put the case here three weeks ago and have to complete it . Sorry for the delay.

Thanks,

cqz