Anterior vs posterior intraocular melanoma. Metastatic differences in a murine model

To study differences in metastatic rate of anterior vs posterior ocular melanoma in a murine model.

Thirty-eight 12-week-old C57BL6 mice were inoculated into the anterior chamber (AC) or posterior compartment (PC) of the right eye with 5 x 10(5) tissue culture Queens melanoma cells per 5 microL. The right eye was enucleated 14 days after inoculation, and the animal was killed 28 days after inoculation and a necropsy was performed. The eye was evaluated for the presence of melanoma and the mean of the 10 largest nucleoli in tumor cells. Eyes with orbital invasion of the melanoma were excluded. The number of metastases was determined at necropsy.

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 group. The metastatic rate was significantly lower for AC tumors (33%) than for PC tumors (89%) (P = .02). All AC tumors that metastasized to lungs also metastasized to ipsilateral cervical lymph nodes, and no PC tumors metastasized to ipsilateral cervical lymph nodes. The median number 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.

Posterior ocular melanoma metastasizes more often than anterior ocular melanoma in this murine model.