Systemic Mastocytosis (Last Updated - 2/26/2005)

-characterized by massive mast cell degranulation
-Heparin appears to be required for the storage of histamine in mast cells --> when mast cells massively degranulate small amounts of endogenous Heparin are released
-may induce a mildly prolonged aPTT

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References:

Goodman & Gilman's: The Pharmacologic Basis Of Therapeutics - 10th Edition - 2001. Chapter 55.