Abstract - Characteristics of Clonal MCAD
J Allergy Clin Immunol. 2010 Jun;125(6):1269-1278.e2.
Clinical, biological, and molecular characteristics of clonal mast cell disorders presenting with systemic mast cell activation symptoms.
Alvarez-Twose I,González de Olano D,Sánchez-Muñoz L,Matito A, Esteban-López MI,Vega A,Mateo MB,Alonso Díaz de Durana MD,de la Hoz B A, Orfao A, et al: Escribano L.Centro de Estudios de Mastocitosis de Castilla La Mancha, Hospital Virgen del Valle, Toledo, Spain.
BACKGROUND: Systemic mast cell activation disorders (MCADs) are characterized by severe and systemic mast cell (MC) mediators-related symptoms frequently associated with increased serum baseline tryptase.
OBJECTIVE: To analyze the clinical, biological, and molecular characteristics of adult patients presenting with systemic MC activation symptoms; anaphylaxis in the absence of skin mastocytosis who showed clonal(c)versus nonclonal (nc) MCs and to provide indication criteria for bone marrow (BM) studies. METHODS: Eighty-three patients were studied. Patients showing clonal BM MCs were grouped into indolent systemic mastocytosis without skin lesions (ISMs(-); n =48) and other c-MCADs (n = 3)-both with CD25(++) BM MCs and either positive mast/stem cell growth factor receptor gene (KIT) mutation or clonal human androgen receptor assay (HUMARA) tests-and nc-MCAD (CD25-negative BM MCs in the absence of KIT mutation; n = 32) and compared for their clinical, biological, and molecular characteristics. RESULTS: Most clonal patients (48/51; 94%) met the World Health Organization criteria for systemic mastocytosis and were classified as ISMs, whereas the other 3 c-MCAD and all nc-MCAD patients did not. In addition, although both patients with ISMs(-) and patients with nc-MCAD presented with idiopathic and allergen-induced anaphylaxis, the former showed a higher frequency of men, cardiovascular symptoms, and insect bite as a trigger, together with greater sBt.Based on a multivariate analysis, a highly efficient model to predict clonality before BM sampling was built that includes male sex (P = .01), presyncopal and/or syncopal episodes (P = .009) in the absence of urticaria and angioedema (P =.003), and sBt >25 microg/L (P = .006) as independent predictive factors.
CONCLUSIONS: Patients with c-MCAD and ISMs(-) display unique clinical and laboratory features different from nc-MCAD patients. A significant percentage of c-MCAD patients can be considered as true ISMs(-) diagnosed at early phases of the disease.