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Start free with EleplanMonoclonal mast cell activation syndrome
ORPHA:529468Disease
Also called Primary MCAS · Clonal MCAS · Monoclonal MCAS
What it is
A rare hematologic disease characterized by symptoms of mast cell activation in the absence of cutaneous findings, as well as absence of diagnostic criteria of systemic mastocytosis with tryptase levels of less than 20 ng/ml and normal to low burden of mast cells. Bone marrow biopsy reveals the presence of monoclonal mast cells carrying the KIT D816V mutation and/or expressing CD25. Patients present with recurrent episodes of flushing, headache, hypotension, abdominal cramping, nausea, diarrhea, cardiac arrhythmias, bronchoconstriction, and bleeding diathesis, among others.
Key facts
- Age of onset
- All ages
- Inheritance
- Not applicable
- Classified as
- Disease
ICD-10 codes
ICD-10 has no distinct code for most rare diseases, so many are filed under the nearest available one. A shared code identifies the group, not this disease — the ORPHAcode above is what identifies it.
Related health topics
Reached through the ICD-10 categories this disease is filed under, so these describe the broader group rather than this disease specifically.
Cross-references
Orphadata Science: Free access data from Orphanet. © INSERM 1999. Data version 2026-06-23. Available under CC BY 4.0. This is a reference, not medical advice.
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