Diagnostic algorithm in SM. Based on the presence of at least one major and one minor or at least 3 minor SM criteria, the diagnosis of SM is established. Thereafter, the patient has to be examined for the presence of B findings, C findings, percentage of MCs in BM smears (to exclude the presence of MCL), and signs of an AHNMD. In patients with 0 or 1 B findings, no C findings, and no signs or symptoms indicating the presence of MCL or AHNMD, the final diagnosis is ISM. In those who present with 2 or 3 B findings but no C findings (and no MCL/AHNMD), the diagnosis of SSM is established. If at least one C finding is present, the diagnosis changes to ASM, and in those who also have at least 20% MCs in their BM smears, the diagnosis changes to MCL. In any variant of SM, an AHNMD may be diagnosed as a concomitant disease. In a final step, the AHNMD variant needs to be determined by WHO criteria.