Pattern discovery. (A) Dendrogram. Hierarchical clustering of the 32 ALCL samples (ALK⁺, 25; ALK⁻, 7) based on 495 probe sets obtained by unsupervised selection (see “Patients, materials, and methods”) using complete linkage. Common type (yes/no) corresponds to morphologic features: “y” denotes common type, and “n” denotes morphologic variants; periv. pattern (yes/no) corresponds to perivascular pattern: “y” denotes presence of malignant cells around vessels (see Figure 2D) and “n” denotes its absence; stage corresponds to Ann Arbor classification I, II, III, IV; relapse (no/early/late): n indicates no relapse; e, early relapse (delay less than 1 year); l, late relapse (delay more than 1 year); ALK corresponds to ALK1 immunostaining: minus = negative/plus = positive. Blanks denote “not available.” Fisher exact test: P values measure association between each annotation and the partition C1/C2. Here, stage was recoded into a binomial variable: low, I-II; high, III-IV. Asterisks indicate the 4 patients with less than 40% of tumor cells: 10% (1 patient), 20% (2 patients), and 30% (1 patie, materials, nt). (B) Dendrogram. Hierarchical clustering of the 25 ALK⁺ ALCL samples based on 198 probe sets obtained by unsupervised selection using complete linkage (see “Patients, materials, and methods”). Fisher exact test: P values measure association between each annotation and the partition C1′/C2′. Here, stage was recoded into a binomial variable: low, I-II; high, III-IV. Asterisks indicate the 4 patients with less than 40% of tumor cells, respectively 10% (1 patient), 20% (2 patients), and 30% (1 patient).