immunology allergic disorders
Mastocytosis and Mast Cell Activation Syndrome
Treatment of Mastocytosis
For cutaneous mastocytosis, H1 blockers and possibly psoralen plus ultraviolet light or topical corticosteroids For systemic mastocytosis and mast cell activation syndrome, H1 and H2 blockers, cromolyn, andketotifen,montelukast,aspirin For aggressive forms,midostaurin,avapritinib,interferon alfa-2b, corticosteroids, or splenectomy Antihistamines are effective for symptoms. Children with cutaneous forms require no additional treatment because most cases resolve spontaneously. Adults with cutaneous forms may be treated with psoralen plus ultraviolet light or with topical corticosteroids once or twice a day. Mastocytoma usually involutes spontaneously and requires no treatment. Treatment includes parenteral All patients with systemic mastocytosis should be treated with H1 and H2 blockers and should carry a prefilled, self-injectingepinephrinesyringe. Aspirincontrols flushing but may enhance leukotriene production, thereby contributing to other mast cell–related symptoms; it should not be given to children because Reye syndrome is a risk. Cromolyn 200 mg orally 4 times a day (100 mg 4 times a day for children 2 to 12 years; not to exceed 40 mg/kg/day) may help by preventing mast cell degranulation.Ketotifen2 to 4 mg orally twice a day may also be effective. No treatment can reduce the number of tissue mast cells. Omalizumabis an anti-IgE antibody that is sometimes used for moderate to severe asthma and chronic urticaria; it has sometimes been used in patients with mastocytosis or mast cell activation syndrome to try to prevent anaphylaxis. ( Treatment references ) can be used to help control end-organ damage, cytopenias, and mast cell accumulation in bone marrow ( Midostaurin100 mg orally twice a day Avapritinib200 mg orally once a day Interferon alfa-2b4 million units subcutaneously once a week to a maximum of 3 million units a day induces regression of bone lesions. Corticosteroids (eg,prednisone40 to 60 mg orally once a day for 2 to 3 weeks) may be required as adjunctive treatment for severe cases. Some limited evidence suggests that splenectomy may improve survival in patients with aggressive disease. Cytotoxic drugs (eg, daunomycin,etoposide, 6-mercaptopurine) may be indicated for treatment of mast cell leukemia, but efficacy is unproved.Imatinib(a tyrosine kinase receptor inhibitor) may be useful when treating adults with aggressive systemic mastocytosis but is ineffective in patients with the D816Vc-kitmutation. Treatment is directed at preventing mediator release (eg, with cromolyn and/orketotifen) and blocking mediator effects with some regimen of H1 and H2 blockers to block histamine,aspirinto block prostaglandins andmontelukastto block leukotrienes. Known triggers should be avoided. 1.Radia D, Deininger M, Gotlib J, et al:Avapritinib, a potent and selective inhibitor ofKITD816V, induces complete and durable responses in patients (pts) with advanced systemic mastocytosis (AdvSM). EHA Library. 2019;267413:S830. 2.Gotlib J, Kluin-Nelemans HC, George TI, et al: Efficacy and safety ofmidostaurinin advanced systemic mastocytosis.N Engl J Med374 (26):2530–2541, 2016. doi: 10.1056/NEJMoa1513098 