. 2021 Oct 13;5(11):e646. doi: 10.1097/HS9.0000000000000646

Table 6.

Proposed Global Classification of Mast Cell Pathologies and Related Conditions.

Disorder/Condition	Diagnostic Criteria/Defining Features
Mast cell hyperplasia	Reactive increase in normal mast cells
	No evidence for clonal mast cells
	Criteria for CM/SM/MCS not fulfilled
Mastocytosis	WHO criteria for CM, SM, or MCS fulfilled
MCAS^a	MCAS criteria fulfilled
	± Criteria for CM/SM/MCS fulfilled
Other MCAD^a	Evidence for a clinically relevant, local or systemic mast cell activation but the criteria for MCAS are not fulfilled^a
Other MCAD^a	± Criteria for CM/SM/MCS fulfilled
MML	Advanced myeloid neoplasm diagnosed
	based on WHO criteria (eg, AML)
	Increase in neoplastic mast cells ≥10%
	Criteria for CM/SM/MCS not fulfilled

^aMCAD can be divided into MCAS and other MCAD. The criteria to be used for concluding that there is evidence of clinically relevant, local, or systemic mast cell activation (disorder) in the absence of criteria that fulfill MCAS are discussed in the Supplemental Digital Content, Table S11, http://links.lww.com/HS/A201.

AML, acute myeloid leukemia; CM = cutaneous mastocytosis; MCAD = mast cell activation disorders; MCAS = mast cell activation syndromes; MCS = mast cell sarcoma; MML = myelomastocytic leukemia; SM = systemic mastocytosis; WHO = World Health Organization.