The most common lesions of the breast are solitary and multiple cysts. Aspiration of the cysts is an excellent procedure for both diagnosis and treatment. Following aspiration of the cyst, it is important to palpate the area again to determine whether a residual mass is present, and if so, additional aspirations of the residual solid area should be performed.
The cyst fluid may be clear, opaque or turbid, yellow, green, brown or red (blood stained). Blood stained fluids are suspicious for cystic carcinoma. Clear fluid is almost always acellular or very poorly cellular, consisting of only a few epithelial cells, often showing apocrine cells and foamy cells.
Breast cysts may become inflamed; aspiration of these cysts usually yields turbid fluid with numerous neutrophils, along with foamy cells and degenerating ductal cells.
The utility of cytological examination of all breast cyst fluids has been questioned, however turbid or bloody fluids should always be submitted for examination. This is also true for fluids from cysts that have refilled within a few days or weeks from a previous drainage procedure.