pS6 staining in lymph node tissue. (A) Stained pS6 area proportion at different lymph node structures for the first cohort of iMCD-TAFRO patients (cohort 1, n = 10) compared with a control group of sentinel lymph nodes (n = 5). Statistical significance, denoted by an asterisk, was calculated using 2-compositional analysis of the centrometric log-rate transformation of the proportions. There were significant increases in pS6 staining in the mantle zone (P = .038) and interfollicular space (P = 3.3 × 10−4), and nonsignificant increases for the entire follicle (P = .050) and germinal center (P = .19). (B) Comparison of various staining intensity proportions of the interfollicular space for cohort 1 and the control group. The results indicate that the iMCD-TAFRO cases had significantly higher medium (P = 3 × 10−4) and strong (P = 6 × 10−4) staining. (C-D) Representative images of pS6 (brown) staining for a sentinel lymph node (C) and an iMCD-TAFRO lymph node (D). Hematoxylin counterstain provides a blue nuclear stain to assess cell and tissue morphology. Scale bars, 200 µm. *P < .05, **P < .01. GC, germinal center; Inter, interfollicular space; MZ, mantle zone.