Mast Cell Activation Syndrome
Image Description
Mast cell activation syndrome (MCAS): Patient with systemic mastocytosis may develop severe systemic symptoms subsequent to release of mediators like histamine, eicosanoids, proteases, and heparin. When such symptoms are accompanied by elevated serum tryptase levels, it fulfills the criteria of mast cell activation syndrome.
MCAS in systemic mastocytosis is analogous to B symptoms seen with certain lymphomas and has clinical and therapeutic implications. MCAS is not synonymous with or a subset of systemic mastocytosis. It can occur in other disorders such as IgE-dependent allergic reactions. Some patients with MCAS do not meet diagnostic criteria for systemic mastocytosis but do show clonal mast cells with KIT D816V mutation or aberrant surface CD25. Such cases are designated monoclonal MCAS.
The photograph shows maculopapular cutaneous mastocytosis (Urticaria pigmentosa). In adults, the lesions are macular and tend to be more heavily pigmented and widely disseminated. System mastocytosis with cutaneous involvement should always be ruled out.
MCAS in systemic mastocytosis is analogous to B symptoms seen with certain lymphomas and has clinical and therapeutic implications. MCAS is not synonymous with or a subset of systemic mastocytosis. It can occur in other disorders such as IgE-dependent allergic reactions. Some patients with MCAS do not meet diagnostic criteria for systemic mastocytosis but do show clonal mast cells with KIT D816V mutation or aberrant surface CD25. Such cases are designated monoclonal MCAS.
The photograph shows maculopapular cutaneous mastocytosis (Urticaria pigmentosa). In adults, the lesions are macular and tend to be more heavily pigmented and widely disseminated. System mastocytosis with cutaneous involvement should always be ruled out.