Specimens obtained from autopsy samples and EMB samples in patients with CS (A–D), M (E–H), and CM (I–L) were stained by haematoxylin and eosin (A, C, E, G, I, and K) and immunostained with anti-P. acnes antibody (B, D, F, H, J, and L). Black arrows indicate positive P. acnes-immunostaining. Minimal inflammatory cell infiltration was observed in samples from all six patients. Even at the lowest inflammatory cell infiltration, positive P. acnes-immunostaining in macrophages of these inflammatory foci was detected in samples from patients with CS (B, D), but not in samples from those with M (F, H) and CM (J, L), regardless of the sample type. Original magnification; ×1000.