A 38-year-old woman presented with a painful mass in her right breast that had been present for a few months. She was six months postpartum, following an uncomplicated pregnancy and delivery. The patient did not breastfeed/chestfeed but reported continued lactation from her right breast. She had a history of fibroadenoma in the right breast, which was biopsied 15 years prior.

Physical examination revealed a large retroareolar mass that was mobile and fluctuant. The patient did not have skin changes or axillary or supraclavicular lymphadenopathy, and milky white fluid could be expressed from the right nipple. The left breast was normal, with no discharge. Laboratory workup showed an elevated prolactin level and a normal thyroid-stimulating hormone level.

Diagnostic mammography and breast ultrasonography demonstrated a mixed attenuation, multiloculated cystic mass with flat fluid levels in the retroareolar aspect of the right breast (Figure 1 and Figure 2). The mass measured 6.9 × 6.2 × 6 cm. Magnetic resonance imaging of the head did not show intracranial abnormalities.

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