[Nevus cell aggregates in axillary lymph nodes in simultaneous mucinous breast carcinoma]

Nevus cell aggregates in lymph nodes are uncommon. This benign phenomenon may be difficult to differentiate from metastatic neoplasia. We report the case of a 56-year-old patient who underwent breast biopsy, followed by radical mastectomy including lymphadenectomy. Histological examination revealed solid cell aggregates as foreign tissue in the capsule of 1 of 11 identified lymph nodes devoid of any keratin immunoreaction. Strong immunohistological staining for the S-100 protein confirmed the diagnosis of nevus cell aggregates.