Correlation of plasma sKIT levels with disease severity.

(A) Plasma sKIT levels correlate with disease severity based on clinical categorization. Category Ia, urticaria pigmentosa without systemic involvement; category Ib, systemic indolent mastocytosis; category II, mastocytosis with an associated hematologic disorder; category III, aggressive mastocytosis. (B) Plasma sKIT levels correlate with disease severity based on bone marrow pathology. Histopathological findings in bone marrow biopsies were graded as follows: grade 1: no evidence of increased mast cell numbers; grade 2: focal mast cell aggregates, normocellular marrow; grade 3: focal or diffuse mast cell aggregates and hypercellular marrow, or presence of a hematologic disorder. Bars represent median values.