Single-molecule RNA in situ detection in clinical FFPE tissue sections by vsmCISH

Detection of HER2 mRNA expression in invasive breast cancer FFPE tissue sections. (A) HER2 IHC 0, RNA score 0. (B) HER2 IHC 0, RNA score 1. (C) HER2 IHC 1+, RNA score 0. (D) HER2 IHC 2+, DNA FISH negative, RNA score 0. (E) HER2 IHC 2+, DNA FISH negative, RNA score 1. (F) HER2 IHC 2+, DNA FISH negative, RNA score 2. (G) HER2 IHC 2+, DNA FISH positive, RNA score 3. (H) HER2 IHC 2+, DNA FISH positive, RNA score 4. (I) HER2 IHC 3+, RNA score 4. (J) Quantification of HER2 mRNA detection in 25 cases of invasive breast cancer FFPE tissue sections, excluding five cases with strong and diffuse expression. (K) The relationship between IHC classification and RNA score. Scale bar, 100 µm.