A 6-year-old girl presented for a second opinion with a 1-year history of an enlarging soft tissue mass just lateral to the right areola. She had been seen by a pediatric surgeon elsewhere who reassured the parents that the lesion was benign. Ultrasound scan showed a 1.5- x 1.5-cm cystic structure adjacent to the right breast bud. Excisional biopsy results showed secretory ductal adenocarcinoma. Modified radical mastectomy with axillary node dissection was performed. All 11 nodes were negative for metastatic disease. She is now disease free 3 years after diagnosis. Estrogen-progesterone receptors were negative, as was screening for BCR 1 and 2. This is the first report of cytogenetics showing an abnormal cell line with a reciprocal translocation between 12p and 15q. Although breast cancer is extremely rare in children, a history of a painless, enlarging, firm breast mass should raise concern about possible neoplastic disease. Cystic appearance on ultrasound scan caused by the pseudocapsule around the tumor may be a marker for secretory carcinoma. Histological evaluation of all suspicious masses should be obtained. Because of the risk of local recurrence and axillary metastases, the authors recommend modified radical mastectomy with axillary node dissection for children with secretory carcinoma of the breast.