Several cases occurring together with fever, polyarthralgia and erythema nodosum were documented. Diagnosis
Characteristic for idiopathic granulomatous mastitis are multinucleated giant cells and epithelioid histiocytes forming non-caseating granulomas around lobules. Often minor ductal and periductal inflammation is present. The lesion is in some cases very difficult to distinguish from breast cancer and other causes such as infections (tuberculosis, syphilis, corynebacterial infection, mycotic infection), autoimmune diseases (sarcoidosis, granulomatosis with polyangiitis), foreign body reaction and granulomatous reaction in a carcinoma must be excluded.The condition is diagnosed very rarely. As the diagnosis is a lengthy differential diagnosis of exclusion there is considerable uncertainty about incidence. It has been suspected that some cases diagnosed as IGM in developing countries may have other explanations. On the other hand, IGM is usually diagnosed only after complications and referral to a secondary breast care center so light cases may resolve spontaneously or after symptomatic treatment and thus never be diagnosed as IGM. As a completely pathogen free breast will be exceedingly rare even in completely healthy population there is also uncertainty when to consider pathogens as causative or as mere coincidental finding. Causes of idiopathic granulomatous mastitis
Causes are not known. The histology is suggestive of an autoimmune reaction. The high rate of relapses as well as relatively high proportion of bilateral cases is highly suggestive of a systemic predisposition. Presently most evidence points towards an important role of elevated prolactin levels or overt hyperprolactinemia with additional triggers such as local trauma or irritation.
Megestrol (INN, BAN) is a progestin of the 17α-hydroxyprogesterone group which was never marketed and is not currently used clinically. Its acylated derivative megestrol acetate is also a progestogen, which, in contrast to megestrol itself, has been extensively used as a pharmaceutical drug. Synthesis
See also
Megestrol acetate
Medroxyprogesterone
Medroxyprogesterone acetate


== References ==