What is Regarding cystic disease of breast which one is true - and explain in detail?
• Occur most commonly in the last decade of reproductive life as a result of a non-integrated involution of stroma and epithelium.
Clinical Features
• Often multiple, may be bilateral and can mimic malignancy.
• Typically present suddenly and cause great alarm; prompt diagnosis and drainage provides immediate relief.
Diagnosis
• Diagnosis can be conﬁrmed by aspiration and/or ultrasound.
Treatment
• Aspiration for Solitary cyst: If they resolve completely, and if the ﬂ uid is not blood-stained, no further treatment is required (30% will recur and require reaspiration) 
• Core biopsy or local excision: If there is a residual lump or if the ﬂ uid is blood-stained, for histological diagnosis (exclude cystadenocarcinoma, which is more common in elderly women)