Snapshot A 28-year-old woman presents to the gynecology clinic with a two year history of breast pain. The pain is worse just before her menses and denies any nipple discharge. Her last menstrual period was six days prior to presentation. There is no family history of breast cancer and her menstrual cycle began at 13 years of age. Physical exam reveals diffuse nodularity in the upper outer quandrants of both breasts. There is no lymphadenopathy. Introduction Clinical definition non-proliferative epithelial lesions of the breast which encompasses a heterogenous group of diagnoses such as breast cysts papillary apocrine change stromal fibrosis Epidemiology Incidence estimated to be about 30-50% of all women, and most common in pre-menopausal women > 35 years cause of benign breast masses cause of green, straw-colored, or brown nipple discharge Etiology Pathophysiology secondary to the effect of hormonal variation on breast tissue for example breast engorgement and mastalgia vary with cycle symptoms regress at menopause Presentation Symptoms bilateral breast pain or tenderness varies with the menstrual cycle nipple discharge Physical exam diffuse bilateral nodularity on palpation discrete cyst(s) physical exam alone cannot distinguish between a cyst and a solid mass Imaging Ultrasound indications in women < 30 years of age Mammography indications in women > 30 years of age evaluation of cysts which persist despite repeated drainage Studies Fine needle aspiration of the cyst confirms the diagnosis aim for complete drainage of the cyst with collapse of cyst wall Histology non-proliferative epithelial lesion breast cysts are most common papillary apocrine change mild hyperplasia Differential Fibroadenoma Galactocoele Treatment Conservative follow-up with serial physical exams and ultrasound indications cyst disappears on aspiration and the fluid is clear classical presentation with no discrete nodules Medical oral contraception indications first-line treatment danazol indications severe symptoms NSAIDS indications mastalgia Surgical excision biopsy indications cysts that persist despite repeated drainage suspicious lesions Complications A risk factor for future breast cancer diffuse nodularity may mask tumor mass Prognosis Symptoms subside after menopause Recur if patient is on hormone replacement therapy Nodularity of breast may mask breast tumors