Antibiotic-refractory unilateral breast abscess with contralateral cystic lesion in a pubertal girl: a case report.

Pediatric breast abscesses require timely infection control while minimizing injury to the developing breast. We report an 11-year-old pubertal girl with persistent left breast pain, swelling, and erythema after 7 days of oral antibiotic therapy. Physical examination revealed a fluctuant left breast mass and a tender contralateral cystic lesion. Inflammatory markers were elevated. Ultrasonography demonstrated a heterogeneous left-sided collection with peripheral vascularity, consistent with abscess formation, whereas the right breast showed a well-circumscribed anechoic cyst without inflammatory features. The antibiotic-refractory abscess was treated by incision and drainage, and the contralateral cyst was managed by needle aspiration. Culture of the purulent fluid yielded Staphylococcus epidermidis. Two-month ultrasonography showed marked lesion reduction. At 12-month clinical follow-up, no recurrence, nipple discharge, or obvious breast asymmetry was observed. The case shows how ultrasonography helped separate an abscess requiring drainage from a contralateral cyst that could be treated by aspiration.