Mouse monoclonal high molecular weight cytokeratin clone 34be12

Four‐micrometre‐thick tissue sections were cut from selected paraffin‐embedded blocks (Superfrost Microscopic Slides; ThermoFisher Scientific, Bleiswijk, The Netherlands). Slides were deparaffinised, and rehydrated with xylene and ethanol. Endogenous peroxidase was blocked with 0.3% H₂O₂ in phosphate‐buffered saline, and heat‐induced antigen retrieval was accomplished by 15 min of incubation in Tris‐EDTA buffer (pH 9; Klinipath, Duiven, The Netherlands). Mouse monoclonal high molecular weight cytokeratin (clone 34BE12; 1:200; Dako, Heverlee, Belgium) diluted in normal antibody diluent (APG‐500; ScyTek Laboratories, West Logan, WV, USA) was incubated for 2 h at room temperature. Antibody visualisation was performed with the Envision kit (Dako) and slide counterstaining with haematoxylin. When basal cell staining was absent, the cribriform structure was classified as invasive carcinoma; if sporadic, scattered or continuous basal cells were identified, the growth pattern was classified as intraductal carcinoma.

Four micrometer thick tissue sections were cut from selected paraffin-embedded blocks and mounted on slides (Superfrost Microscopic Slides, ThermoFisher Scientific, Bleiswijk). Slides were deparaffinized and rehydrated with xylene and ethanol. Endogenous peroxidase was blocked using 0.3% H₂O₂ in phosphate-buffered saline. Heat-induced antigen retrieval was accomplished by 15 min in Tris-ethylenediaminetetraacetic acid buffer (pH 9; Klinipath, Duiven, The Netherlands). Mouse monoclonal high-molecular weight cytokeratin (clone 34BE12; 1:200; DAKO; Heverlee, Belgium) diluted in normal antibody diluent (APG-500; ScyTek Laboratories, West Logan, USA) was incubated for 2 h at room temperature. Antibody visualization was performed using the Envision kit (DAKO) and slide counterstaining with hematoxylin. When basal cell staining was completely absent around a cribriform gland, it was categorized as invasive cribriform carcinoma; if sporadic, scattered, or continuous basal cells were identified the structure was classified as intraductal carcinoma.