Can it be that a brain tumor cause photosynthesis ( being sensitive to light )?

Possible: Sensitivity to light can be due to meningeal involvement with tumor, usually metastatic tumor.

Yes and no: "photosynthesis" is not something the human body does; it is what green plants do when in sunlight to convert the energy in the light to sugar using carbon dioxide, water, and the special cellular structures called chloroplasts. However, it is certainly possible for some brain tumors to give a patient light sensitivity. There are many other causes of such sensitivity, don't jump to conclusions.