NODAL NEVI AND CUTANEOUS MELANOMAS

Nevocytes in melanoma-draining lymph nodes can be mistaken for melanom a metastases and may possibly transform to melanoma. During the develo pment of a new technique for managing high-risk primary melanomas, sel ective lymph node dissection, we examined 4,821 nodes from 208 melanom a patients by light microscopy and immunohistochemistry. Nodal nevi we re identified in 49 of 226 lymphadenectomy specimens (22%), a frequenc y considerably higher than previously recorded (5-6%), Nevi occurred i n 57 of 4,821 nodes (1.2%), in 84% of patients in one node, in 13% of patients in two nodes, and in 3% of patients in three nodes, Nevocytes were detected in hematoxylin and eosin-stained sections in 38 of 49 c ases (78%) and exclusively by immunocytochemistry with an antibody to S-100 protein in 11 of 49 (22%). Nevi were In the peripheral capsule i n 93% of cases and in internal trabecula in the remaining 7%, Nevocyte s surrounded a small vessel in 33% of cases. Nevi were more frequent i n axillary (37 of 140, 26%) and cervical nodes (seven of 40, 18%) than in inguinal nodes (five of 46, 11%). Nevi were more frequent in senti nel nodes, the first nodes on the lymphatics draining a primary melano ma (11 of 284, 3.9%), than in nonsentinel nodes (46 of 4,537, 1.01%; p < 0.0008). One of 1,071 nodes from 50 patients with breast cancer (0. 1%) and none of 521 nodes from 50 patients with pelvic cancer containe d nevocytes. That nodal nevi are selectively present in melanoma patie nts raises the possibility of their origin from nodal melanocytes infl uenced by tumor products, Alternatively, the association may indicate that the nevocytes of cutaneous nevi can be disrupted and displaced by the growth of an adjacent melanoma.