title: Systemic Mastocytosis.
abstract: An unusual disease, mastocytosis challenges the pathologist with a variety of morphologic appearances and heterogeneous clinical presentations ranging from skin manifestations (pruritus, urticaria, dermatographism) to systemic signs and symptoms indicative of mast cell mediator release, including flushing, hypotension, headache, and anaphylaxis among others. In this article, we focus on recognizing the cytology, histopathology, clinical features, and prognostic implications of systemic mastocytosis, a clonal and neoplastic mast cell proliferation infiltrating extracutaneous organ(s) with or without skin involvement. Diagnostic pitfalls are reviewed with ancillary studies to help unmask the mast cell and exclude morphologic mimics.
authors.affiliation: Department of Pathology, Stanford University School of Medicine, Stanford University Medical Center, 300 Pasteur Drive, Room H1501B, Stanford, CA 94305-5627, USA. Electronic address: tigeorge@stanford.edu.
authors.forename: Tracy I
authors.initials: TI
authors.lastname: George
authors.affiliation: Institut für Pathologie, Klinikum Ansbach, Escherichstrasse 6 DE-91522, Ansbach, Germany.
authors.forename: Hans-Peter
authors.initials: HP
authors.lastname: Horny
keywords: KIT D816V; Mast cell; Mast cell leukemia; Systemic mastocytosis