Coincidence of mammary and sentinel lymph node papilloma

This report describes an unusual case of mammary intraductal papillomas coexistent with sentinel lymph node papilloma. A 47-year-old Japanese female underwent 5 needle manipulations and 2 surgical biopsies for recurring papillomas in the right breast over 5 years before having a simple mastectomy. During the mastectomy, the ipsilateral sentinel node was found to be extensively occupied by completely benign papilloma that measured 6 mm in its greatest dimension. The clinical history led us to put forward the working hypothesis that the nodal papillary lesion may develop from the epithelial cells that are displaced from the mammary papillomas during needle procedures and mechanically transported to the sentinel lymph node. To test the hypothesis, we retrieved surgical biopsies (dochectomy and excisional biopsy), mastectomy, and sentinel lymph node specimens for histopathologic, immunohistochemical, and molecular studies. The presence of myoepithelial layer in each papillary tumor was confirmed by immunostains with specific myoepithelial markers, p63 and CD10. The excisional biopsy specimen exhibited displaced fragments of benign epithelial cells within granulation tissue at the needle manipulation site, indicating that iatrogenic epithelial cell displacement did occur in this case. However, loss of heterozygosity at 16p13 and 16q21 was only observed in the papillomas of the dochectomy and the excisional biopsy; no loss of heterozygosity was detected in the papillomas of the mastectomy and the sentinel lymph node. It remains undetermined whether the nodal papilloma was derived from the papilloma of the mastectomy or if it arose de novo from the breast tissue inclusion of the sentinel node.