Patient presents with complaints consistent with a possible left breast cyst.  Chief complaint includes palpable lump left breast, possibly accompanied by intermittent breast pain or tenderness in the left breast.  On physical examination, a discrete, mobile, well-circumscribed mass is palpated in the left breast.  The mass is non-tender or mildly tender and exhibits fluctuation consistent with a cystic lesion.  No nipple discharge or skin changes are noted.  Differential diagnosis includes fibrocystic breast changes, fibroadenoma, and breast cyst.  Ultrasound of the left breast was performed and confirms a simple cyst, anechoic, with posterior enhancement, measuring [size] cm.  No solid components or suspicious features identified.  Impression:  Simple left breast cyst.  Plan:  Patient education provided regarding breast cysts and self-breast examination.  Observation and follow-up recommended.  Consider aspiration if the cyst becomes symptomatic or increases in size.  ICD-10 code N60.01, Left breast cyst.  Patient understands the plan and will return for follow-up as needed.