In vitro characteristics of uveal malignant melanomas.

During a 17-month period, 33 histologically proved posterior uveal melanomas were prepared for in vitro cultivation in our laboratory. Nine of these remained in culture from five to 12 passages. Four tumors histologically classified as heavily pigmented spindle B cell type remained as pigmented spindle cell tumors in primary culture. During subcultivation one culture lost pigmentation and exhibited mixed cells. Three other tumors, classified histologically as lightly pigmented spindle B cell type, appeared as amelanotic mixed cells in primary culture and grew as epithelioid cells during subcultivation. Two tumors classified as mixed cell type grew as spindle cells in primary culture. One of these last cultures reverted to mixed cell type on subcultivation. One cell culture has shown pigmentary and morphologic changes with variations in carbon dioxide level and media composition.