Benign nevus cells in the lymph nodes. An immunohistochemical study.

Aggregates of nevus cells in the axillary lymph nodes may give rise to a suspicion of metastatic breast cancer. Usually the nevus cells are confined to the capsule or the trabeculae, but in the present case, clusters of nevus cells were also observed in the peripheral sinus. Immunohistochemical analysis for S-100 protein and epithelial membrane antigen established the true nature of the cells.