A 42-year-old asymptomatic Turkish woman, para 2, presented with areas of focal fibroglandular asymmetry in the right breast on screening mammography. There was no personal or family history of breast carcinoma. She delivered her last child 4 years before presentation and had breastfed continuously for 2 years. Sonographic evaluation revealed oval, well-defined, benign-appearing isoechoic-hypoechoic masses suggestive of fibroadenomas, at 6, 9, and 10 o'clock (Fig. 1). The lesion in the 6 o'clock subareolar location was palpable to the breast surgeon.
Ultrasound-guided core biopsies of all three lesions were performed. The pathology results were benign, with the pathology from the palpable lesion at 6 o'clock remarkable for findings of benign breast tissue with marked inflammation, multinucleated giant-cell reaction, and abscess formation. As the patient was asymptomatic, and the imaging appearance was not concordant with an acute abscess, the pathologic findings were thought to represent a chronic process. Clinical followup was the agreed-upon course of management.
Five weeks later, the patient returned with erythema, swelling, and drainage of purulent fluid through several skin ulcers and fistulas in her right breast. These findings began a few days following the core biopsies (Fig. 2). Antibiotic treatment for postbiopsy mastitis was initiated. Ultrasound revealed a 5cm complex fluid collection with sinus tracts centered between the 6 o'clock and the 9 o'clock positions (Fig. 3). Fluid aspirated from the collection was negative for malignant cells or bacterial growth. As the mastitis worsened, methicillin-resistant Staphylococcus aureus (MRSA) was considered. The patient was switched to the appropriate broad-spectrum antibiotics. Repeat aspiration did not reveal any organisms.
Evaluations for tuberculosis and sarcoidosis were negative. As the swelling, erythema, and fistula formation persisted, the decision was made to undergo surgical debridement. Surgical pathology revealed marked non-necrotizing granulomatous inflammation, predominantly periductal in location, with an exuberant acute and chronic organizing inflammatory response. The patient's clinical condition improved markedly following the debridement.