IDENTIFICATION OF SUBMICROSCOPIC LYMPH-NODE METASTASES IN PATIENTS WITH MALIGNANT-MELANOMA

In order to detect micrometastatic disease, our laboratory has develop ed a method for evaluating lymph node sections from patients with stag e 1 or 2 melanoma. Lymph nodes isolated from standard dissections are bivalved; one half is subjected to routine histopathological evaluatio n and the other half disrupted and placed into cell culture. The cultu red cells are identified by cytologic examination, immunohistologic st aining, and the presence of melanoma-associated antigens. Lymph nodes (448) from 62 patients with malignant melanoma were evaluated by tissu e culture. Fifteen patients were upgraded from stage 1 or 2 to stage 3 disease after micrometastases were identified in lymph node cultures. Recurrence of disease in histologically node negative patients, durin g a mean 24-month follow-up, has only been observed thus far in patien ts with culture positive lymph nodes. In addition. these results add e vidence to the belief that missed micrometastatic disease in regional nodes is a sign of occult systemic metastases that would account for t he defined recurrence rate in histologically node negative patients.