Carbon dye histologically confirms the identity of sentinel lymph nodes incutaneous melanoma

Background. False-negative results from lymphatic mapping and sentinel lymp h-adenectomy (LM/SL) are associated with technical failures in nuclear medi cine and surgery or with erroneous histologic evaluation. Any method that c an confirm sentinel lymph node (SN) identity might decrease the false-negat ive rate. Carbon 2 dye has been used as an adjunct to assist lymphadenectom y for some tumors, and the authors hypothesized that it could be used for t he histologic verification of SNs removed during LM/SL. The current study a ssessed the clinical utility of carbon dye as a histopathologic adjunct for the identification of SNs in patients with melanoma and correlated the pre sence of carbon particles with the histopathologic status of the SNs. Methods. LM/SL was performed using carbon dye (India ink) combined with iso sulfan blue dye and sulfur colloid. Blue-stained and/or radioactive lymph n odes (two times background) were defined as SNs. Lymph nodes were evaluated for the presence of carbon particles and melanoma cells. If an SN lacked c arbon dye in the initial histologic sections, four additional levels were o btained with S-100 protein and HMB-45 immunohistochemistry. Completion lymp h node dissection (CLND) was performed if any SN contained melanoma cells. Results. One hundred patients underwent successful LM/SL in 120 lymph node regions. Carbon particles were identified in 199 SNs from 111 lymph node re gions of 96 patients. Sixteen patients had tumor-positive SNs, all of which contained carbon particles. The anatomic location of the carbon particles within these tumor-positive SNs was found to be correlated with the locatio n of tumor cells in the SNs. The presence of carbon particles appeared to b e correlated with blue-black staining (P = 0.0001) and with tumor foci (P = 0.028). All 35 non-SNs that were removed during LM/SL were tumor-negative, and only 2 contained carbon particles. Of the 272 non-SNs removed during C LND, 5 contained metastases; 3 of these 5 were the only non-SNs that had ca rbon particles. The use of carbon particles during LM/SL was found to be sa fe and nontoxic. Conclusions. Carbon dye used in LM/SL for melanoma permits the histologic c onfirmation of SNs. Carbon particles facilitate histologic evaluation by di recting the pathologist to the SNs most likely to contain tumor. The locati on of carbon particles within SNs may assist the pathologist in the detecti on of metastases, thereby decreasing the histopathologic false-negative rat e of LM/SL and subsequently reducing the same-basin recurrence rate. Cancer 2001;92:535-41. (C) 2001 American Cancer Society.