I have seen similar patterns with several lenses in situations where the sun is focused on a obviously very bright spot on the sensor. As I have seen now and the sort of a Bayer RGGB pattern, I am convinced that this is a greatly magnified, and usually poorly focused, image of the bright spot reflected back onto the sensor by the residual reflections on some lens surface. I specifically remember an image with the AF-S 18-35mm f/3.5-4.5 lens.
Here is one: 18-35 at 29mm f/16 on D800 left third of image, upper 2 thirds. contrast processed to enhance visibility of effect. (Yes, there is dirt on the sensor)