A rare haematologic disease characterised 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 mg/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. Symptoms include recurrent episodes of flushing, headache, hypotension, abdominal cramping, nausea, diarrhoea, cardiac arrhythmia, bronchoconstriction and bleeding diathesis. [from
SNOMEDCT_US]