Nodal blue nevus: a pitfall in lymph node biopsies.

The sentinel lymph node from a 72-year-old female with melanoma revealed a pigmented and spindled melanocytic proliferation in the capsule that extended into the trabeculae. Benign nodal nevi are uncommon but have been reported in lymph nodes of melanoma patients and less often in lymph nodes removed for other reasons. Nodal blue nevi are particularly rare. These melanocytic proliferations can be distinguished from metastatic melanoma by evaluation of the distribution in the node, morphologic characteristics and the assistance of immunohistochemistry.