Are breast cysts always benign?
"On her annual physical, my 29-year-old patient discovered a 1.5 cm mass in the axilla," reports KAREN PACKER, MD, of Cochrane, AB. "Ultrasound reported a cyst in the tail of the breast. She eventually had it biopsied and it was, in fact, a malignant tumour. She now has bilateral breast cancer. I was taught that breast cysts are always benign. Is this true?"
In medicine, nothing is always or never. The vast majority of breast cysts are benign, especially in premenopausal woman. If the cyst fluctuates with the cycle, it's often benign. But if it's persistent or returns after aspiration, or if the aspiration is bloody or the cyst complex, then the clinician must be more suspicious. Twenty percent of women have cysts greater than 1 cm and 7% are clinically detectable. Although it's impossible to aspirate each one, they could potentially be intracystic carcinomas or arise secondary to a malignant ductal obstruction. Breast cancer would be very low on the differential in a 29-year-old, but it can occur, even in a teenager. BC