We would like to draw your attention to the new nomenclature for mast cell activation: following recent publications, we are now talking about NC-MCD (Non-Clonal Mast Cell Disorder) when the blood tryptase level is normal.
The NC-MCAS is used if the tryptase is above the norm.
MCAS is said to be "primary" if there is a clonal disease (mastocytosis = mast cell cancer due to proliferation of a clone following a mutation = clonal mast cell disorder mastocytosis) or secondary (e.g. when IgE is elevated, or if there is an underlying disease such as generalized urticaria, autoimmune disease or other) or idiopathic MCAS (always with elevated tryptase) if no other contributing cause is established. With a normal tryptase (which is most often the case in EDS), we speak of "non-clonal mast cell disorder" and not MCAS.
To be correct in the title, it should be non-clonal mast cell activation syndrome or non-clonal mast cell disorder (not a cancer): NC-MCAS or NC-MCDs depending on the case.
In order to qualify as NC-MCDs/NC-MCAS, there must be symptoms, even if frustrating, in at least two to three systems: skin, digestive system, respiratory system, cardiovascular system, neurological system or urogenital system.
NC-MCDs (and more rarely NC-MCAS) are present in approximately 80% of patients with Ehlers-Danlos syndrome.
The treatment of NC-MCD or NC-MCAS is the same and must be adapted on a case by case basis.
Good to all,
Dr Stéphane Daens. President of GERSED Belgium, coordinator of a national network of experts Orphanet / INSERM