This large series of cases demonstrates that the breast of the child or adolescent is the potential site for a number of interesting lesions exclusive of fibroadenoma and gynecomastia. Adenoma of the nipple, juvenile papillomatosis, and juvenile or cellular fibroadenoma should be correctly diagnosed to insure conservative surgical management and appropriate clinical follow-up. The results of the Juvenile Papillomatosis Registry suggest that this lesion is a morphological marker of potentially more serious breast disease in the future. Recognition of a cellular fibroepithelial neoplasm, especially in young black females, as a cellular fibroadenoma will hopefully eliminate the need for the diagnosis of "benign" cytosarcoma phyllodes. On occasion, the equivocal case may be labeled a "phyllodes tumor fo indeterminate biologic behavior." Those neoplasms with stromal atypia and mitotic activity, overgrowth of stroma with epithelial dissociation, and sarcomatous elements are appropriately designated as cytosarcoma phyllodes. In contrast to vascular tumors of the breast in adults, the majority of vascular lesions in the child's breast are bening and represent either a capillary or a histiocytoid hemangioma. Our experience and reports in the literature support the conclusion that most malignancies of the breast in children are metastatic. Rhabdomyosarcoma was the most common example in our study, but secondary involvement by acute leukemia or malignant lymphoma also occurs.