EWGBSP CIS vs MIC STUDY 3
Please, read this carefully.
In this study we have two series of cases so TWO circulations.
In the SECOND series/second circulation we have cases from 1 to 50. (The numbers have been mixed up, and they do not correspond to the original numbers!) Although the cases are the same altogether, please try to do the classification by completely ignoring the first series.) Each case has 4 jpg slides (additional to the 5 H&E from round 1) named: f, g, h and i (which are at magnifications 5X, 10X, 20X, 40X, respectively) and are IHC stains for myoepithelium (calponin or myosin smooth muscle or p63). You can access the slides at: https://www.kmk.hu/info/ewgbsp3 . You can also download the materials (slides, instructions and spreadsheet) at: https://www.kmk.hu/info/ewgbsp3
Because of previous experience with similar studies, may I just quote to you a text by our group about the definition. (This is at the end of this text – try to adhere to it as much as possible)
The aim of the study in this case is only to assess the diagnostic reproducibility of microinvasion therefore the excel file is much shorter, with only one column to fill in.
A tumour in which the dominant lesion is in-situ carcinoma (usually extensive high nuclear grade DCIS, rarely other types of DCIS or lobular intraepithelial neoplasia) but in which there are one or more clearly separate foci of infiltration of non specialized interlobular or interductal fibrous or adipose tissue, none measuring more than 1 mm (about 2 hpf) in maximum diameter. (27,28,29). This definition has been officially reported in the TNM system as pT1mic since 1997 (fifth edition)(30). It is very restrictive and tumours fulfilling the criteria are consequently rare.
The tumour focus/foci must invade into nonspecialized interlobular or interductal stroma (extension of the lesion beyond the confines of a ductolobular unit, development of a desmoplastic stroma). The cells deemed to be invasive must be distributed in a fashion (non-organoid pattern) that does not represent tangential sectioning of a duct or a lobular structure with in-situ carcinoma. Tangentially sectioned in-situ carcinoma foci that simulate microinvasion are distributed in the specialized periductal and intralobular stroma and usually occur as compact groups of tumour cells that have a smooth border surrounded by a circumferential layer of myoepithelial cells and stroma or a thickened basement membrane (29). At sites of microinvasive foci, tumour cells are distributed singly or as small groups that have irregular shapes reminiscent of conventional invasive carcinoma with no particular orientation (29). There is complete absence of surrounding basement membrane and myoepithelial cells: immunostains are helpful in demonstrating the presence or absence of basement membrane components (laminin and collagen type IV) or myoepithelial cells (smooth-muscle actin, calponin, smooth-muscle myosin heavy chain). Detecting microinvasion can be difficult when there is a marked periductal fibrosis or inflammation because the true boundary of the specialized periductal or lobular stroma is not clear, but immunostaining for cytokeratin may be useful to confirm the presence of separate foci of neoplastic cells embedded in periductal fibrosis or inflammation.”
E(C)WGBSP: Quality assurance guidelines for pathology. Wells CA (ed)