Nodal melanocytic nevi in sentinel lymph nodes. Correlation with melanoma-associated cutaneous nevi.

Melanocytic nevi occurring in lymph nodes create diagnostic difficulty by mimicking metastases. Few studies describe nodal nevi in sentinel lymph nodes (SLNs) excised for melanoma. We evaluated 72 cases in which patients had undergone SLN biopsy for melanoma. Lymph nodes and cutaneous melanomas were evaluated according to a standard protocol. Nodal nevi were identified in 8 patients (11%). Of these, 6 (75%) had an associated cutaneous nevus (P = .006). Of 21 patients with an associated nevus, 4 (19%) with nodal nevi had a cutaneous nevus with congenital features (P = .01). The incidence of nodal nevus correlated with a Breslow thickness greater than 2.5 mm (P = .02). Nevi were not seen in non-SLNs. Nodal nevi appear more frequently in patients with melanoma-associated cutaneous nevi, particularly if congenital features are present. The increased frequency of nodal nevi in SLNs relative to non-SLNs suggests an etiology of mechanical transport of nevus cells.