ERBB2 and glycogen storage disease VI: Plasma cells were associated with favourable outcome among some ER-positive subgroups (IntClust 4+, IntClust 8, and IntClust 7) but not among other subgroups (pheterogeneity = 0.03), while activated mast cells were associated with poorer outcome in IntClust 5 (HER2-positive disease), IntClust 8, and IntClust 9 but not others (pheterogeneity = 0.03).