CD4 and Buschke-Ollendorff syndrome: Among CD4 + cells, the median (range) percentage IL-26 positive cells was 6% (4–7) in the BOS group (n = 3) and 4% (4–10) in the non-BOS group (n = 3). Among CD8 + cells, the median (range) percentage IL-26 positive cells was 9% (9–15) in the BOS group and 8% (3–15) in the non-BOS group. Representative flow cytometry images are shown in Fig. 4.