The SM diagnostic toolkit. Establishing a diagnosis of SM and staging the extent of disease require integrated clinical, histopathologic, laboratory, radiology, and molecular/cytogenetic testing. Referral to specialized centers with expertise in mastocytosis is recommended given the rarity of these diseases, particularly advSM variants. AHN, associated hematologic neoplasm; ASO-qPCR, allele-specific oligonucleotide quantitative polymerase chain reaction; CT, computed tomography; DEXA, dual-energy x-ray absorptiometry; GI, gastrointestinal; MRI, magnetic resonance imaging.