TGM2 and ductal breast carcinoma in situ: Considering our hypothesis that TG2 might represent an early sensor of tumor-induced modification in the stroma, we evaluated TG2 expression at protein level by IHC separately in stroma and in the tumor compartments of 5 patients diagnosed with DCIS and who later developed in invasive tumor matched with 5 women of similar age and diagnosed with DCIS lesions of comparable grade and size, albeit free of invasive relapse for a similar follow up duration.