CD34 and systemic mastocytosis: In the human system, KIT is employed as a surface marker to detect normal and neoplastic MCs (KIT+/CD34‐) by flow cytometry.2, 8, 49, 50, 51, 52, 61 In addition, KIT is employed together with tryptase to detect and enumerate neoplastic MCs in the BM of patients with SM by immunohistochemistry.65, 66 In adult patients with SM, the activating KIT mutation D816V is detected in a vast majority of cases.