Paragonimiasis in a cystic breast mass: case report and implications for examination of aspirated cyst fluids.

We report a case of paragonimiasis diagnosed by fine-needle aspiration of a breast mass in a middle-aged Korean female with a history of breast silicone injections. Although parasitoses have been discovered by aspiration of cyst fluid in otherwise sterile sites (i.e., liver and lung), the cystic presentation in the breast of a middle-aged female complicated the diagnosis in this case. Some authors have argued against the routine cytologic examination of nonbloody cyst fluids in premenopausal women, but this protocol may lead to a false negative diagnosis in the rare instance of a parasitic cyst. While microscopic examination of breast cyst fluid is probably not warranted in every patient, it may be useful in patients at risk for unusual cystic lesions, especially if clinical and mammographic signs of fibrocystic change are absent.