Lymphatic diameters and radionuclide clearance in a murine melanoma model

S. D. Nathanson, M. Avery, P. Anaya, T. Sarantou and F. W. Hetzel
Department of Surgery, Case Western Reserve University, Henry Ford Health System, Detroit, Mich., USA.

OBJECTIVES: To determine the clearance of a radionuclide from various sizes of footpad melanomas via lymphatics and to measure the diameters of these vessels. DESIGN: Nonrandomized animal study. SETTING: A hospital research laboratory. SUBJECTS: C57BL/6 mice. INTERVENTIONS: Female mice were injected in the right rear footpad with B16 F10 cells that were allowed to grow to either 1, 2, 3, 4, or 5 mm in anteroposterior diameter. Clearance from feet with or without tumors of injected technetium Tc 99m human serum albumin (99mTcHSA) was assessed for 200 minutes. Calf lymphatic diameters were measured using aniline blue dye. RESULTS: The clearance of the injected 99mTcHSA from mouse footpads without tumors was 1.26 +/- 0.18 x 10(-4) mL/min x cm3 of tissue. Clearance increased 2.24-fold to 2.82 +/- 0.12 x 10(-4) mL/min x cm3 of tissue from 1-mm tumors and to 6.20 +/- 0.08, 6.11 +/- 0.13, 6.91 +/- 0.58, and 7.23 +/- 0.48 x 10(-4) mL/min x cm3 of tissue from 2-, 3-, 4-, and 5-mm tumors, respectively (P < .05). Calf lymphatic diameters increased from 75.41 +/- 9.72 microns in naive nontumor-bearing mice to 93.51 +/- 7.12, 111.61 +/- 27.07, 126.69 +/- 25.20, 124.43 +/- 24.75, and 127.44 +/- 25.35 microns in mice bearing 1-, 2-, 3-, 4-, and 5-mm tumors, respectively (P < .01). CONCLUSIONS: There was a size-dependent, direct correlation between increasing tumor size in the footpad and increasing diameter of lymphatics draining the footpad. Clearance of injected 99mTcHSA from these tumors also exhibited a similar positive correlation with tumor size.