It appears to me to be a capsular contracture. Capsular contracture is the result of excess scar developing around a breast implant, making the breast appear hard and round. If severe, the scar tissue can develop a separation from the normal tissue of the breast, which is what I think may be happening here.
Aja Rock’s Breasts – What’s Going On Here?
While Aja Rock has caught the media's attention ... there are thousands of women similarly disfigured by dangerous implants.
“Aja Rock appears to have a complication of breast implants called capsular contracture,” said Plastic surgeon Dr. Anthony Youn to NZ Reality TV. “This is the result of excess scar tissue developing around an implant, making it appear hard and firm. In addition, it can cause a separation to form between the actual breast tissue and the scar tissue. This is what appears to be happening here.” says Dr. Youn.