Mastocytosis

Abstract

Mast cells (MCs) are generally recognized as the principal cell types to initiate IgE-dependent, type I immediate hypersensitivity reactions, and more recently as cells that might also contribute to innate and acquired immunity and to tissue remodeling [1, 2]. A cell destined to be an MC will leave the bone marrow as an immature mono-nuclear progenitor, probably with multipotential capabilities, enter the circulation still without characteristic secretory granules and surface with high affinity IgE receptor (FcεRI) expression, but complete differentiation into a mature MC only after arriving at peripheral tissues such as lung, bowel, and dermis. Haematoxylin and eosin do not routinely stain MCs. The aniline dye in toluidine blue solution, however, changes the color in MC granules from blue to pinkish-purple, a phenomenon that Ehrlich called metachromasia, enabling the identification of the abundant number of MCs even in normal human skin tissue where MC density has been estimated to range from 7,000 to 10,000/mm 3 [3, 4] Mastocytosis is a range of heterogeneous disorders associated with abnormal regulation of MC development and proliferation, which consist essentially of normal-looking MCs [5, 6]. The clinical manifestations are directly related to tissue infiltration of MCs, which maintain their regular distribution, and to the release of chemical mediators by MCs resulting in skin rash, gastrointestinal symptoms, syncope, anaphylaxis, osteoporosis, organomegaly, and hematological disorders. © 2010 Springer-Verlag Berlin Heidelberg.