Allergic etiology of benign fibrocystic changes of the breast.

We postulate that fibrocystic changes in the female breast are the end result of a series of biochemical events initiated by the mast cell degranulation products histamine and heparin. Two mechanisms are proposed which could lead to mast cell degranulation in breast tissue. First, low progesterone levels lead to decreased intracellular cAMP levels in mast cells which enhance mast cell degranulation. Second, low progesterone levels lead to increased solubilization of breast collagen during tissue turnover. Susceptible individuals may undergo an allergic reaction to soluble collagen resulting in further mast cell degranulation. The degranulation products histamine and heparin may stimulate increased stromal proliferation and vascularization respectively. We provide evidence for the occurrence of histamine release by demonstrating an increased incidence of allergic symptoms in white women with fibrocystic breast changes.