Abstract
Background Systemic mastocytosis (SM) comprises a heterogeneous group of disorders characterized by the proliferation of clonal mast cells in skin and various internal organs. Omalizumab is an established, labelled therapy for allergic asthma and chronic urticaria, but its experience in the efficacy of SM is limited. Methods A retrospective analysis of 6 patients diagnosed with indolent SM treated with omalizumab at St. Michael's Hospital between 2009 and 2018 is described. Reported frequency of anaphylaxis, baseline and follow-up tryptase levels, and SM-related symptoms were captured to measure the control of the disease. Results Of the 5 patients who had experienced unprovoked anaphylaxis prior to treatment with omalizumab, 3 had no further episodes of anaphylaxis following initiation of omalizumab, while the remaining 2 patients had milder multisystem reactions. Significant improvement in cutaneous symptoms was also observed. Conclusion These data suggest that omalizumab provides benefit to patients with SM who remain highly symptomatic in spite of treatment with conventional therapies.
Highlights
Systemic mastocytosis (SM) comprises a heterogeneous group of disorders characterized by the proliferation of clonal mast cells in skin and various internal organs
Systemic mastocytosis (SM) comprises a heterogeneous group of disorders characterized by accumulation of clonal mast cells (MCs) in various internal organs, including the bone marrow (BM), spleen, liver, and gastrointestinal tract (GI) as well as the skin [1,2,3]
A 28-year-old male developed urticaria pigmentosa confirmed by skin biopsy in 2008. e number of skin lesions had been gradually increasing over the course of 6 years
Summary
Systemic mastocytosis (SM) comprises a heterogeneous group of disorders characterized by accumulation of clonal mast cells (MCs) in various internal organs, including the bone marrow (BM), spleen, liver, and gastrointestinal tract (GI) as well as the skin [1,2,3]. Binding of the kit ligand, stem cell factor (SCF), to the kit receptor is important for the normal development and function of MCs from their hematopoietic progenitors [4]. Alpha tryptase is released constitutively from MC and reflects the total body MC burden, whereas beta tryptase is a marker of MC activation [6, 7]. Case Reports in Hematology omalizumab may provide additional benefit for patients with SM with recurrent anaphylaxis despite maximal mast cell blockade. We describe the efficacy of omalizumab in 6 patients with indolent SM, who experienced recurrent anaphylaxis refractory to maximal medical therapy
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