Acellular dermal matrix used for lumpectomy cavity volume replacement mimicking as breast cancer recurrence: a case report

: Acellular dermal matrix (ADM) has been used as a soft tissue replacement since its introduction in 1994. There is an emerging practice of filling the defects during breast conservation surgery (BCS) exclusively with diced ADM. A 57-year-old female with no family history of malignancies presented to our institution after undergoing left breast lumpectomy and sentinel lymph node biopsy for early stage left breast cancer at another facility in December 2019. Final histopathology revealed a low grade Invasive Ductal Carcinoma of the left breast of TNM stage pT1cN0M0, Estrogen/Progesterone receptors were positive, HER-2/neu was negative and the resection margins were negative for malignancy or atypia. Genetic profiling revealed high risk of recurrence and accordingly she received adjuvant chemotherapy and radiotherapy and was maintained on hormonal therapy. Six months after surgery, a surveillance chest computed tomography (CT) showed a 5.7 cm × 3.5 cm × 2.7 cm mass with a lobulated margin in the vicinity of the resected tumor in left breast and residual disease or recurrence could not be ruled out. Clinical examination did not reveal any suspicious ipsilateral breast mass, or pathological skin/nipple changes. Focused left breast Ultrasound (US) at the same time showed a 7.7 cm × 2 cm × 4.4 cm artificial appearing mass with a smoothly marginated border and swirling debris at the site of the previously resected malignancy. We contacted her surgeon and learned that in fact the patient had undergone the new procedure of lumpectomy cavity volume replacement with diced ADM. The literature on imaging features of ADM remains limited and imaging diagnosis of ADM remains largely based on clinical history and short-term follow-up. Therefore, ADM has increasingly become a differential consideration in diagnostic imaging, following reconstructive breast surgeries. This case describes the radiological features 6 months after using diced ADM in immediate reconstruction after BCS. These findings remain diagnostically challenging for radiologists and surgeons. Definitive diagnosis relies on clinical correlation.