Some cases are due to silicone injection (Silicone-induced granulomatous inflammation) or other foreign body reactions.
[citation needed] Characteristic for idiopathic granulomatous mastitis are multinucleated giant cells and epithelioid histiocytes forming non-caseating granulomas around lobules.
Presently most evidence points towards an important role of elevated prolactin levels or overt hyperprolactinemia with additional triggers such as local trauma or irritation.
Similar cases of granulomatous mastitis were reported in IgG4-related disease though the exact relationship to IGM remains to be elucidated.
[4][5][9][10][11] Elevated prolactin levels have the direct effects of increasing secretory activity of breast lobules, maintaining tight junctions of the ductal epithelium, preventing involution of the breast gland after weaning and are known to stimulate the immune system.
[12] Autoimmune reaction to extravasated fat and protein rich luminal fluid (denaturized milk) resulting from the secretory activity is assumed to be one of the triggers of IGM.
High levels of insulin caused, for example, by peripheral insulin resistance, resulting from pregnancy, gestational diabetes or developing diabetes mellitus type 2, will enhance the galactogenic and antiapoptotic effects of PRL and growth hormone by acting synergistically with IGF-1.
[18] This organism, first isolated from human sputum in 1998, requires lipids for its growth which may help to explain its association with this condition.
[19] One review recommended complete resection or corticosteroid therapy, stating also that long-term follow-up was indicated due to a high rate of recurrence.
[4] Treatment with a combination of glucocorticoids and prolactin lowering medications such as bromocriptine or cabergoline, was used with good success in Germany.
Its principal mechanism of action is immunomodulating activity, with a side effect profile that is more favorable for treating IGM.