Granulomatous lesions of the breast are rare. They can be secondary to systemic conditions (sarcoidosis), infections (mycobacterium, fungal), or reactions to foreign material (silicone, narcotics).
A detailed history may point in the direction of the diagnosis. Clinical examination usually reveals a palpable, firm mass in the breast.
Depending upon underlying etiology, there may be mammographic changes of an ill-defined lesion. Frequently, these are associated with coarse calcification.
The pathology of specific granulomatous infections or conditions such as Sarcoidosis or Wegeners granulomatosis is similar to that seen for these conditions in other sites.
Idiopathic granulomatous mastitis and silicone mastitis merit special mention.
Idiopathic granulomatous mastitis is a granulomatous lesion centered around ducts and lobules. No caseation or noncaseous necrosis is seen and no foreign material or pathogens are present within the lesion. Occasional small microabscesses may be present.
Silicone mastitis has a histologic appearance similar to that of fat necrosis. There are foamy macrophages and occasional multinucleate giant cells arranged in a random fashion, but poorly formed granulomata may be present.
The silicone may be apparent as highly refractile, irregular particles both within the phagocytic cells and lying free in the extracellular location.
No active treatment is required once the diagnosis has been established histologically. If in doubt, excision is performed.
A.D. Purushotham, P. Britton and L. Bobrow
A prospective study of benign breast disease and the risk of breast cancer. JAMA 2002