Breast assessment, screening & benign disease: a free FRCS (Gen Surg) Section 1 question

This is a simple breast cyst, an aberration of normal involution that peaks in the decade before the menopause. When imaging shows a simple cyst, the aspirate is not bloodstained and the lump resolves completely, no further action is needed: cytology of ordinary cyst fluid has a negligible yield of cancer and generates false-positive atypia, so the fluid is discarded. Cytology or biopsy is indicated when the fluid is uniformly bloodstained, a mass persists after aspiration or imaging shows an intracystic or solid component. Scheduled repeat ultrasound is unnecessary, as she can return if a lump recurs, and many cysts refill harmlessly. Excision of a simple cyst is not indicated. Reference: Dixon JM (ed.), Breast Surgery: A Companion to Specialist Surgical Practice, 6th edn; Willett AM et al., Best practice diagnostic guidelines (2010).