Vital dye and carbon solution for sentinel lymph node biopsy in rats

Objective: To characterize if blue vital dye and carbon solution allowsurgeons and pathologists identify sentinel nodes, not impairingthe pathological examination. Methods: Sixty young adult femalerats were studied. Three groups of 20 animals were formed andreceived a blue solution containing 0.5, 1 and 6% of activated carbon,respectively. An injection of patent blue solution with activated carbonwas done in the ventral aspect of the right hindpaw. Thirty minuteslater, a sentinel node biopsy was performed. Sentinel nodes weresubmitted to conventional histological study to identify the presenceof activated carbon particles within the lymph nodes, as well astheir location and distribution. Results: In the group treated with 6%activated carbon solution, identification of activated carbon particleswas possible in all 20 slides at 100x magnification; in the 1% group,200x magnification was necessary. In the last group, 0.5%, in six slideswas necessary to use the immersion technique (100x magnification)for correct identification; all 14 slides were adequately studied at 400xmagnification. Conclusions: The identification of carbon particles in thehistological study was possible in the three groups of activated carbonand patent blue solutions. However, the best solution of vital dye withthe least activated carbon concentration was the 0.5% group