A Giant Invasive Cribriform Carcinoma Presenting as a Breast Abscess: A Case of Massive Cystic Degeneration

Invasive cribriform carcinoma (ICC) is a rare, well-differentiated subtype of breast cancer that usually presents as a small, slow-growing solid mass. We report a 57-year-old woman with a giant, painful left breast mass clinically mimicking a breast abscess. Ultrasonography showed a large mixed cystic–solid lesion, and aspiration yielded approximately 900 mL of bloody fluid. Core needle biopsy confirmed ICC of the Luminal A subtype. Neoadjuvant chemotherapy showed limited efficacy, and the patient first underwent sentinel lymph node biopsy (1/8 positive), followed by modified radical mastectomy with axillary lymph node dissection, with postoperative pathology revealing sentinel lymph node metastasis in 1 of 8 nodes. This case highlights that ICC can rarely present as a massive cystic lesion with inflammatory features, and malignancy should be suspected when bloody fluid is aspirated from a presumed breast abscess.