CAP TODAY每期中都有一个提问和回答（Q&A）专栏，其中不少涉及到解剖病理学中常见的问题，现在我将这个Q&A贴出来，与大家一起分享，也希望各位网友踊跃将其翻译成中文，让更多的同行学习交流。

What are the limitations of using myoepithelial markers in diagnostic breast pathology?

Immunohistochemical studies using antibodies to highlight myoepithelial cells (MEC) can be useful adjuncts to traditional morphologic diagnosis in the practice of breast pathology. Antibodies commonly
used to detect MEC include smooth muscle actin, calponin, smooth muscle myosin heavy chain, p63, CD10, cytokeratin 5/6, and p75, and each shows varying sensitivity and specificity. 1–4 The presence of MEC may indicate a noninvasive process, but there are several settings in which caution should be exercised when
interpreting immunohistochemical results. For example, sclerotic lesions, such as radial scars and sclerosed papillomas, may show decreased numbers of MEC or decreased intensity of expression of MEC markers.4,5 Moreover, if the lesion has been previously biopsied, MEC may not be well preserved due to disruption and
reaction to the procedure. Myoepithelial markers may also be absent in the setting of ductal carcinoma in situ (DCIS), especially high-grade DCIS.5 The question of microinvasion associated with high-grade DCIS is a common diagnostic dilemma. One can be confident of a noninvasive process if at least some MEC are present
surrounding the suspicious area. However, the absence of MEC in this setting does not guarantee an invasive process. It is recommended that a panel of MEC markers be used, rather than relying on a single antibody. In general, the presence of MEC supports a noninvasive process, but there are instances
when invasive carcinoma may show myoepithelial differentiation. For instance, adenoid cystic carcinoma expresses p63. Metaplastic carcinomas, as well as triple-negative carcinomas with basaloid features, express myoepithelial markers. 6 In general, the irregular infiltrative pattern on H&E is characteristic of invasive carcinoma, but being aware of myoepithelial differentiation in these settings will prevent confusion in interpretation. In summary, the presence of MEC supports a noninvasive process, but the results of immunohistochemical studies for MEC expression should be interpreted within the morphologic
context.
References
1. Moritani S, Kushima R, Sugihara H, et al. Availability of CD10 immunohistochemistry as a marker of breast
myoepithelial cells on paraffin sections. Mod Pathol.2002;15:397–405.
2. Collins LC, Schnitt SJ. Papillary lesions of the breast: selected diagnostic and management issues. Histopathology.2008;52:20–29.
3. Werling RW, Hwang H, Yaziji H, et al. Immunohistochemical distinction of invasive from noninvasive breast
lesions: a comparative study of p63 versus calponin and smooth muscle myosin heavy chain. Am J Surg Pathol.2003;27:82–90.
4. Hilson JB, Schnitt SJ, Collins LC. Phenotypic alterationsin myoepithelial cells associated with benign sclerosing lesions of the breast. Am J Surg Pathol. 2010;34:896–900.
5. Hilson JB, Schnitt SJ, Collins LC. Phenotypic alterations in ductal carcinoma in situ-associated myoepithelial cells: biologic and diagnostic implications. Am J Surg Pathol. 2009;33:227–232.
6. Rakha EA, Putti TC, Abd El-Rehim DM, et al. Morphological and immunophenotypic analysis of breast carcinomas with basal and myoepithelial differentiation. J Pathol. 2006;208:495–506.
Jean F. Simpson, MD
Vanderbilt University
Nashville

 试着翻译了一下，第一次翻译外文，有不妥的地方请各位老师指教。

什么是乳腺病理诊断中肌上皮应用的局限性？

免疫组化使用抗体显示肌上皮细胞被应用在乳腺病理的形态学诊断上面，标记肌上皮的抗体一般有SMA、calponin、SMMHC、P63、CD10、CK5\6和P57，每一种标记物显示有不同的敏感性和特异性，肌上皮的的存在显示一种非侵袭性的过程。但是在免疫组化结果的解释中有几种情况应该被特别被注意，例如：硬化性病变，放射状瘢痕，硬化性乳头状病变，可能显示肌上皮细胞减少或者阳性表达很微弱，此外，如果病变部位以前被活检过，由于对组织损伤过程的反应及活检部位的破坏，肌上皮可能显示的不是很清楚，肌上皮标记物在DCIS时也可能会消失，特别是高级别的DCIS，有关高级别DCIS伴微浸润的问题一直是一个难点，如果可疑浸润部分只有部分肌上皮围绕，这对确定微浸润是一个很好的帮助，但是，如果病变部位缺乏肌上皮包绕也不是一个能肯定是浸润的证据，所以，肌上皮标记物的使用应推荐使用一组抗体，而不是单个抗体的简单应用，一般来说，肌上皮的存在代表一个非侵袭性的过程，但是，有证据表明，浸润性癌也会有肌上皮的分化，例如：腺样囊性癌表达p63，化生性癌、显示基底细胞样特征的三阴癌表达肌上皮的标记物，一般来说，不规则浸润是HE切片上浸润性癌的一个特征，但是意识到肌上皮分化有时存在于这些例子中有助于防止混淆，概括起来，肌上皮的存在支持一个非浸润性的过程，但是免疫组化结果的解释必须建立在形态学的基础之上。