Nevus cell aggregates associated with lymph nodes. Immunohistochemical observations.

Nevus cell aggregates occurring in association with axillary lymph nodes can be difficult to recognize and differentiate from a metastatic breast carcinoma. We believe S100-protein immunoreactivity, along with negative staining for keratin and epithelial membrane antigen, and typical geographic distribution of nevus cell aggregates in lymph nodes are helpful in providing an accurate diagnosis.