ANTERIOR VS POSTERIOR INTRAOCULAR MELANOMA - METASTATIC DIFFERENCES IN A MURINE MODEL

Objective: To study differences in metastatic rate of anterior vs post erior ocular melanoma in a murine model. Methods: Thirty-eight 12-week -old C57BL6 mice were inoculated into the anterior chamber (AC) or pos terior compartment (PC) of the right eye with 5 x 10(5) tissue culture Queens melanoma cells per 5 mu L, The right eye was enucleated 14 day s after inoculation, and the animal was killed 28 days after inoculati on and a necropsy was performed. The eye was evaluated for the presenc e of melanoma and the mean of the 10 largest nucleoli in tumor cells. Eyes with orbital invasion of the melanoma were excluded. The number o f metastases was determined at necropsy. Results: Melanomas grew in 30 of 38 eyes. After exclusion of 9 eyes with orbital invasion of tumor, melanoma was found in 12 mice in the AC group and 9 mice in the PC gr oup. The metastatic rate was significantly lower for AC tumors (33%) t han for PC tumors (89%) (P=.02). All AC tumors that metastasized to lu ngs also metastasized to ipsilateral cervical lymph nodes, and no PC t umors metastasized to ipsilateral cervical lymph nodes. The median num ber of pulmonary metastases per tumor was significantly smaller for AC tumors than for PC tumors (P=.01) There was a median of 0 metastases (range, 0-14) per AC tumor and 4 metastases (range, 0-38) per PC tumor . Conclusion: Posterior ocular melanoma metastasizes more often than a nterior ocular melanoma in this murine model.