Systemic mastocytosis

Mastocytosis is a heterogeneous group of disorders characterized by clonal expansion of mast cells. Clinical course can range from no or minimal symptoms to diffuse systemic involvement with multiorgan failure. The diagnosis of systemic mastocytosis primarily relies on the identification of neoplastic mast cells (spindle-shaped cells expressing CD2/CD25) in various organs, especially the bone marrow. Serum tryptase and urinary histamine levels are typically elevated. There is no effective treatment for systemic mastocytosis. Most patients are treated with antihistamines for symptom control. For patients with aggressive disease, cytoreductive therapy with interferon alfa or cladribine is indicated. The KIT gene D816V mutation is present in approximately 90% of patients and several medications targeting this KIT mutant are currently being investigated. As no established treatment regimen exists, enrollment into a clinical trial should be strongly considered.