Unsupervised hierarchical clustering of the in situ samples. (a) Dendrogram of all 40 in situ samples. (b) Scaled-down representation of the entire cluster of (a) (5,788 genes). (c) Dendrogram of only the well- (n = 6) and poorly (n = 14) differentiated ductal carcinoma in situ (DCIS) cases. (d) Entire cluster of (c) (4,493 genes). Yellow indicates well-differentiated DCIS, brown indicates poorly differentiated DCIS, black indicates DCIS samples with an intermediately differentiated component, and gray indicates special cases. i, intermediately differentiated; IHC, immunohistochemistry; i-p, intermediately-poorly differentiated; LCIS, lobular carcinoma in situ; p, poorly differentiated; w, well differentiated; w-i, well-intermediately differentiated.