Juvenile papillomatosis (JP) is a benign proliferative disease of the breast affecting young women. Some patients with JP develop breast carcinoma. We recently treated and followed a case of JP in a 16-year-old female, and studied its immunohistochemical characteristics. The patient noticed a small tumor, 5 mm in diameter, in the periareolar region on the medial side of the right breast. She underwent an excisional biopsy and pathology demonstrated JP. However, 6 months later, two new lesions were discovered by routine echogram examination, and were later excised. Immunohistochemistry demonstrated that the JP tumors were negative for estrogen receptor, but positive for progesterone receptor, epidermal growth factor receptor and erbB-2. In addition, tests for p53 were negative and Rb protein was normally expressed. Immunohistochemical analysis suggested that an abnormality in estrogen receptor is important in the pathogenesis of JP, and that the patient had a relatively high risk of developing breast carcinoma, since her JP is multicentric and recurrent. The present study also suggests that immunohistochemical pathology may be beneficial in assessing the malignant potential of JP.