Table 4.
Classification of MCASs
| Category and variants | Proposed criteria |
|---|---|
| Primary MCAS | MCA criteria fulfilled and MC (mono)clonality proven (CD25+ MCs and/or KIT D816V)1 |
| Mastocytosis (Mono)clonal MCAS | |
| Secondary MCAS | MCA criteria fulfilled and criteria for the diagnosis of allergy or other diseases that can produce MCA fulfilled as well |
| Allergy | |
| Other underlying disorder2 | |
| Idiopathic MCAS3 | MCA criteria fulfilled, but no disease that could lead to MCA diagnosed |
1
CD25+ MCs plus KIT D816V detectable, or KIT D816V detectable, but MCs cannot be demonstrated to express CD25.
2
Disorders associated with MCA include autoimmune diseases, certain bacterial infections and some adverse drug reactions.
3
Idiopathic MCAS is a final diagnosis but needs an extensive workup in order to exclude all potential underlying conditions and disorders. Idiopathic and secondary MCA episodes may occur at different time points in the same patient.