(A) BST values over time in 4 patients with indolent SM. Patients 1, 11, 13, and 14 are shown in whom some BST values are above and others fall below 20 ng/mL. Patient 6 is not shown because tryptase is not a WHO minor criterion in those diagnosed with SM-AHN. There was no acute allergic reaction, renal injury, or cytoreductive treatment used at the time of BST measurement at any timepoint. (B) CD117 and CD25 IHC are shown for patients 1 and 9 with indolent SM as well as patient 15 with WDSM. Original CD25 IHC core biopsy slides for patients 1 and 9 were negative (not shown). Patients 1 had new core slides cut and stained for CD117 and CD25 IHC at a second pathology lab and results showed colocalization of CD25 expression with CD117-positive cells. Patient 6 (not shown) had results similar to that of patient 1. Patient 9 had new core and clot slides cut and stained for CD117 and CD25 IHC at a second pathology lab and results showed colocalization of CD25 expression with CD117-positive cells (see insert) in the clot but not the core. The discordance between the core and the clot CD25 IHC for patient 9 suggested that the core biopsy decalcification procedure contributed to a false-negative result. Patient 15 with WDSM had large aggregates of round MCs. CD25 colocalized to CD117-positive cells in a cytoplasmic rather than plasma membrane distribution (see insert).